Troubleshooting 2 Stroke Ignition Problems

Author: Stuart Buckingham   Date Posted:30 March 2017 

The most common thing I get asked over the phone to assist with is diagnosing outboard ignition problems. Whilst I am always happy to try and help in diagnosis, it can be very hard to do so over the phone. Apart from having the right tools to assist in diagnosis, a basic understanding of how a two stroke ignition system works is fundamental. The following is a list of what makes up an ignition system from start to finish.

1. Battery

Your boat battery is where it all starts. Outboards require higher cold cranking amps than many other engines and therefore a dedicated marine battery with the correct cranking capacity for your outboard is a must. Without the correct voltage, your outboards starter motor may not be able to crank the flywheel fast enough to activate your ignition system.

2. Ignition Switch

To activate your engine and crank it over you need a switch. Every electric start outboard has an ignition switch and it will open and shut the starter solenoid. It also turns the engine off by shorting the CDI unit (power pack or switchbox) to ground. A faulty ignition switch can cause all sorts of problems with your ignition system and is more often than not overlooked.

3. Starter Solenoid

This is effectively a gate. The ignition switch sends a signal to the solenoid when you turn your key allowing it to open; this allows voltage from your battery to pass through it to the starter motor. If you're turning your key and the starter motor isn't cranking then you may have a faulty solenoid.

4. Flywheel

When your starter motor is turning over it is spinning your flywheel to create voltage for your ignition system and battery charging system. On the inside of the flywheel are magnets that spin around a stator at high speed to create AC voltage. The flywheel also spins around the trigger (or timer base) to determine your engines firing sequence or timing. Broken or loose magnets on your flywheel will cause ignition issues so they are definitely worth checking.

5. Stator

Your stator creates voltage for two reasons. To send voltage to your CDI unit (power pack or switchbox) to run your engine and to send voltage to your rectifier/regulator that will charge your battery. Engines with no spark or intermittent spark on one bank can be caused by a faulty stator.

6. Trigger

Nestled in with the stator under the flywheel is the trigger (or timer base). Probably the most overlooked part of the ignition system the trigger sends a signal to the CDI unit (power pack or switchbox) and tells it when to release voltage to the coil. A faulty trigger will result in no or intermittent spark and is often misdiagnosed as a fault with the power pack. Additionally, a faulty trigger shorting to ground will damage a power-pack so be careful if fitting a new power pack.

7. CDI Unit

Depending on your outboard brand these units will go by different names but, they will all have the same function and that is to store voltage from the stator and release it to your ignition coil when the trigger tells it to. Often a faulty CDI unit will see intermittent or no spark on cylinders and may only breakdown when your engine warms up.

8. Ignition Coil

Receiving voltage from the CDI unit the coil will amplify voltage and shoot it through to the spark plug. Faulty or damaged coils will have weak or no output. We see a lot of coil failures where customers are using a spark plug that is not recommended by the manufacturer.

9. Spark Plug

This is the last component in your ignition system. The spark plug receives voltage from your ignition coil and creates a small electrical spark within your engines combustion chamber igniting your engine's fuel and creating the explosion that drives the piston to spin the crankshaft and the flywheel where the ignition process begins over and over again. Spark plugs can foul up with oil and carbon on two stroke engines resulting in poor spark. They are by far the easiest part to check first.

10. Rectifier/Regulator

Fitting in somewhere between all this is your engines rectifier/regulator. It is always working and its job is to replace the voltage in your battery that you've lost due to engine cranking, using electric tilt and trim, running fish finders, lights or other accessories on your boat. It converts the AC voltage to DC voltage and regulates how much voltage it is putting into your battery. In a lot of cases, a rectifier/regulator also sends the signal to your RPM gauge (tacho) telling you what revs your engine is doing. Sometimes the first sign of a faulty rectifier/regulator is when your RPM gauge stops working and this is very common with older Evinrude/Johnson outboards.


There are variances here and there, but I’ve gone for the most common and basic approach on this occasion. I hope the above has given you some insight into how your outboard ignition system works. Keep these points in mind if you ever have a potential ignition problem and hopefully, it will make a diagnosis that bit easier.  But remember, in order to diagnose ignition problems properly a Digital Multimeter with a Direct Voltage Adaptor (DVA) is a must have tool for accurate diagnosis. Another very helpful piece of material is the CDI Electronics Troubleshooting Guide, click here for pages of helpful information on almost every two stroke engine.

To shop our range of ignition parts, click here.

Comments (128)

1998 115 Johnson smoking

By: on 3 September 2020
My 115 Johnson seems to be using about twice the oil that it should. It has excessive smoke upon start-up but runs great at most speeds. I does dye sometime at no-wake speed for a long period of time.

Outboard Spares Response
Hi, My thoughts are you have a problem with the VRO Oil Injection unit. Perhaps a split diaphragm allowing excess oil to pass through. This could be why it dies as idle sometimes due to it fouling the plugs. Good Luck.

1988 Evinrude 120 will start, but dies.

By: on 2 September 2020
The incident... Motor runs great. Backed into water Saturday and it started but ran bad... Started 20 times but would bog n shut off. Came home... the carb cowling was FULL of fuel... Float was stuck on top left carb leaking fuel. Took carb apart and cleaned. Motor now starts but runs say 2sec-5 sec and dies. plugs were covered in fuel. Went back and took all carbs apart and cleaned... new plugs. Same... motor starts and runs 2sec-5 sec and dies. I use timing light... No fire on turning over... but random it would fire...Start.. and shut down with no fire again via timing light. if i wiggle the kill switch just right.. it would Start and ran for almost a minute... then died... no spark via timing light. Did this 20 times. Swap to a new battery as i was running it down. open shifter box... cut wire to kill switch...(by the way im no marine mechanic and am lost)... Still no start. I think i did something wrong and use a gator jumpers and put wires back togther... still no start/spark. i diconnect jumper wire.. kill switch is open circut maybe... still no start/spark. I wiggle all the wires to ignition swith, every wire on motor...Motor starts/ dies but runs 20 sec... back to no fire... Wiggle wires to ignitiin switch and beat on shifter box... Boat cranks up and runs 2 minutes this time... then dies... no spark. Ok... im thinking ignition switch... kill switch... I go to my pile of parts... grab an shifter to a 74 johnson 115 i had. OMC so i think it should work. i drag shifter and cables to motor... diconnect the red plug... plug in the "other" shifter box. push key in... i here click from choke...(guess thats choke)... so i go ahead and turn over motor with "other shifter). Turns over... no start.. no spark. Now the original shifter has two plugs going into engine... the big red one... and a smaller one... that i thought is maybe tilt n trim? my "other older shifter" doesnt have trim... so just one cable and big red plug. anywho... try one more time... no start/no spark. Its midnight so done. Im thinking faulty ignition switch.. and i wanna replace kil/lanyard switch... But, im puzzled by plugging in older shifter box and it not starting... as i just knew it was gonna crank... i was wrong. I plan on buying a ignition switch and kill switch tomorrow... but im not expecting it to start since it didnt with the old shifter... looking for advice please

Outboard Spares Response
Hi, Wow, that's a long evening right there! Ok, so make sure everything is connected up as it was before you had the problem. Now, disconnect the kill wire (black with yellow trace) from the power-pack. This means you are going to remove the kill wire from the harness plug that connects to the power-pack plug. If the engine now runs fine, you have a problem with either the ignition switch, kill switch OR the engine harness. If the there is still an issue, i'd be checking spark again. If you can get your hands on a spark tester that allows you to connect all 4 spark plug leads at once that would be beneficial. You can then pinpoint which cylinder or cylinders if any have no spark. Then it's just a matter of working out if you have a problem with a specific ignition component. Let us know how you go. Cheers

1972 Evinrude Lark 50 2 stroke

By: on 27 August 2020
So the post about “running like a champ out of water and half throttled in water” is exactly the problem I had. Also it would bog down with the cover on but second I took it off it revved up and ran mint until I turned it off. So after cleaning my carbs it wouldn’t spark, and noticed most of the gaskets in that area were bad so I ordered new carb repair kits, magnetos/ignition coils and plugs. Had it running mint with the muffs, only problem was it would start to die down and I had to squeeze the primer bulb to keep her running. But she did run mint. Now I’m getting little spark TO the plug but almost nothing THROUGH the plug. What do you think about this ? Also Is there a way to test my parts before ordering new?

Outboard Spares Response
Hi, It sounds to me like an exhaust issue. You possibly have a leaking base gasket and that's why when the engine is in the water and the gearbox/exhaust has back pressure it doesn't run. It also explains why with the cover off it runs better as the motor cover will be filling up with exhaust gas. When the covers off it gets fresh clean air. Good Luck

1984 evinrude V-6 150 35 amp ignition problems

21 May 2020
So I just got this boat about a month ago and honestly is the first outboard I’ve ever owned (always inboards). Runs fine on mufs in the driveway and even in the water while I’m neutral, I can rev it as high as I want. I put in gear and can run around all day at idle speed. The moment I give it throttle in gear it cuts out and dies. Took it to a certified mechanic and he ran through the ignition system, swapping power packs and checking with a DVA. His Diagnosis, only firing in one bank cylinders 1,3 and 5 not on 2,4 and 6 caused by a bad Stator. So I got it home ordered a new 35 amp OEM Stator, installed it and went back to the lake and no change. So I have replaced the $350 Stator and still no fix. What are the possible options here and how do I fix it? 2 little boys dying to go fish off the boat so I’m willing to pay for someone’s time if need be I just want it fixed.

Outboard Spares Response
Hi, it is frustrating when replacing something doesn't fix the problem, especially when you are now $350 out of pocket. There are a few other things it could be. I'd say it is most likely a power-pack or timer base issue. Swap the packs over from one bank to the other. If the spark moves to the other bank then one of the power-packs is faulty. If the problem is still there then disconnect the stop wire from each of the power-packs (black with yellow trace) and re-test. If the problem is still there, then I'd be leaning to a faulty timer base. If the problem has gone (after disconnecting the black/yellow wires) then the stop circuit/harness potentially has an issue. See how you go. Good Luck.

no power to Starter Motor

By: on 19 April 2020
I have an old V6, 2 stroke Mercury which I think is 200hp which I think is 1979 Black max. Recently the ignition key broke and I replaced it with a new key and the ignition switch turns Ok but now I get no response from the starter motor. The yellow and red wire to the solenoid has no voltage when I turn the key but the carbi choke solenoid still activates. I took the boat in to me Mercury service expert for checking and he told me to get a new starter motor. I got a new one and installed it my self. There was nothing wrong with the old starter motor. Can you give me some clues what to check? I don't want to go back to the Mercury service centre if I can do some diagnosis myself first. The engine normally runs very well and I service it regularly myself since it is a very old engine. The S/N is A8061737

Outboard Spares Response
HI, I'd be checking that when you installed the new switch you've correctly wired the ignition wire in properly. Also check the throttle arm is in the neutral position as it could be "in gear" cutting out any voltage to the solenoid. There is a neutral switch in the control box or on the engine, I can't recall exactly but it'll be where the control cables slide on the engine if it's located there. I'm pretty confident this will be the issue. Cheers

Runs good out of water but bad in water

By: on 6 April 2020
I have a 1993 mercury 25hp that im having an issue with. On muffs and water hose it runs like a champ but put it under a load it the river it idles rough, has slow response to the throttle, and when the throttle is wide open im only traveling at half speed. I have cleaned and rebuilt the carb, checked for blockage in the exhaust, check the plugs and done a successful compression test but still no results. Any help??

Outboard Spares Response
Hi Steve, It could be a couple of things but I would look for the most simple solution first. I would first check engine height. Have you fitted a 20 inch leg to a short shaft transom? The cavatation plate above the propeller should be level (or within about 20mm) of the bottom of the boat. My thinking is that if your engine leg is really deep in the water you'll have too much exhaust pressure on the engine causing rough idling and it won't allow you to run your engine to run as it should. If that is all ok, it could also be a faulty ignition coil breaking down under load, or a stator issue also. It's a bit hard to say exactly. Check the engine height first and then maybe check your coils for bad earth or cracks in them that may cause them to short to ground. Good Luck.

1982 35 HP Johnson Outboard Model J35ELCND

By: on 5 April 2020
I have a 1982 35 HP Johnson Outboard (Model J35ELCND). Just cranks over (cranks over fast new battery and starter) and does not even attempt to start. Removed carburetor looked good cleaned anyways put back together....nothing. Checked for spark by removing and monitoring the spark plugs while cranking spark. Shot a squirt of either in carburetor to confirm and nothing so it appears there is absolutely zero spark on both cylinders. Went through wiring harness to see if any obvious disconnects or something...just some missing insulation on some of the wires....taped them up the areas where the insulation was coming off the wires. I made sure the ignition coils where well grounded to engine....still nothing. Not sure where to go next and advise would be greatly appreciated. Thank you Jim

Outboard Spares Response
Hi Jim, I would start by disconnecting the stop wire going into the powerpack from the stop button. It could be you have a short to ground between the stop button/switch and the power-pack. Cheers

85 force

By: on 2 April 2020
Hi..i have a 86 bayliner capri my first boat 17ft 2 strokes outboard motor it's a 85 force Now I go to turn on my battery big red switch to 1 ..2..and all...and my starter come on just like that without I using the ignition switch..what can cause that to happen

Outboard Spares Response
Hi, I would think that it could be one of 3 things in my opinion. 1) the wiring to the starter solenoid is incorrect (possible wired directly to the starter motor? or a jumper wire bridging the solenoid poles) 2) your starter solenoid is faulty 3) your ignition switch is faulty. Go through these things one by one and I am sure you'll find the issue.

Mercury 2015 60hp

By: on 1 April 2020
I replaced the fuel filter, cleaned the spark plugs and the battery is around 12.90 volts. It cranks but will not turn over. Everything in the motor looks to be doing what it should be.

Outboard Spares Response
Hi, Check your "kill" switch on the control box, or on the engine (if it's a tiller control). Make sure the lanyard is attached and the switch is in the RUN position. I'm assuming due to the year this engine is a 4 stroke. Normally these are a great engine. If it's not something as simple as the "kill" switch you may need to take it to a dealer and have them plug the diagnostic tool into it. Cheers

starting problems 1999 35hp johnston

By: on 29 March 2020
I bought this motor recently and it will just not start,I have checked compression which is 150 psi each cyl and the spark test shows spark to each cyl. I have now tested the choke valve and notice it does not activate (checked Solenoid as OK ). I checked the fuel filter and carbys which have fuel. I suspect controller fault,can you advise please (motor cranks well with good battery )

Outboard Spares Response
Hi, It may have spark but if the timing is "out" then this could cause the issue you are experiencing. These engines had numerous issue with the Power-packs so I wouldn't rule out an ignition issue. Otherwise, it is hard to say. If you've got spark, compression and fuel then that really leaves timing in my opinion. That could be a pack issue or a flywheel that has spun on the key. It's always hard to make an "educated guess" over the phone or internet. Just double check, everything you've already done in-case you've overlooked something too. Good Luck.

1999 Mariner 9.9hp 2 stroke

By: on 26 March 2020
I’ve had no spark on either cylinder. The stator had no resistance. Replaced the stator and realized that the plastic bulb on the trigger broke off. It’s for the piece that connects to the shifting linkage. Replaced that and the switch box. Now I’m getting spark but the engine won’t catch. There was also a somewhat moderate volume pop but engine wouldn’t catch. Any ideas?

Outboard Spares Response
Hi, Sounds like it is possibly a timing issue. I'd be checking the flywheel has not spun off the key on the crank-shaft. Just double check that the parts you have received ignition wise (stator, pack, timer base), are all 100% for you engine model. Also ensure your coil primary leads from the pack are to the correct coils. Send us an email if you're still stuck. Cheers

Boat performance in water

By: on 25 March 2020
Hi. I have a evinrude 1985 90hp outboard which was sitting around for a couple of years before it was installed. It starts first time everytime. Out of the water the engine revs and accelerates fine but in the water it is quarter of the speed when throttle is right down. Outward could the issue be. Thanks.

Outboard Spares Response
HI, If the engine has been sitting around for a couple of years then I would be looking at pulling the carburetors off, disassembling them and giving them a good clean. As the engine is under load trying to push the boat through the water it requires more fuel than it would revving up out of the water. If there is gunk in the carburetors then it won't be getting sufficient fuel. Give them a clean and then see how you go. Cheers

1995 mercury Force 40hp

By: on 24 March 2020
My boat wont go over 10mph. Motor runs fine at idle. When I try to throttle up all the way it acts like it's not supplying enough fuel to go fast. Replaced plugs,new carb,and fuel filter. Both cylinders are firing. Compression test 120 both cylinders. My rpm gauge has not been working. And noticed my amp gauge at idle is 13 but when I'm going my top speed it goes down to 11. Thanku for any info.

Outboard Spares Response
Hi, If your engine is a 1995 model then it will be running CDM type coils. These are prone to breaking down under-load when they are faulty or due to be replaced. It could also be a rectifier/regulator issue. Try disconnecting the yellow wires from the stator that go to the rectifier and re-test. If the engine now improves then the rectifier/regulator has an issue. This is where I would start. First test the rectifier/regulator, second look at the CDM's. I hope this helps. Cheers

1992 mercury 40 4 cylinder

By: on 20 March 2020
Hey I have a 40 4 cylinder that I have replaced the stator and trigger on twice. About to be the third. What would make it keep doing this? Thanks chris

Outboard Spares Response
HI, A switch-box with a shorted SCR can ruin a perfectly good trigger and vice-versa. I would replace the trigger and switchbox together. I can't think of why the stator would be compromised in all of this. Are you sure the stator is faulty?? If not, replace the trigger and switch-box together. NOT one at a time, TOGETHER. Then run the engine. Hopefully a faulty switch-box and trigger have been the cause of your issues all along and this should sort you out. Cheers

1992 Mercury 135 v6

By: on 15 March 2020
Mercury 135hp v6 will not rev past 5000rpm. I have checked all spark plugs and number 5 was black with carbon/oil I then changed the coil, HT lead and spark plug and the same thing happened. I thought an ignition pack would cause 1,3 and 5 to go bad I am lost. Thanks.

Outboard Spares Response
Hi, Your problem could be a faulty ignition pack (switch box) but if this has not resolved the issue and either has changing over the coil, then I'd look at the timer base (trigger). A faulty trigger shorting to ground can cause the switch box to fail so hopefully this is not the case and you won't have to replace another switch box. Test the trigger. Between the following wires you should have 800-1400 resistance. Brown (black sleeve) to White (yellow sleeve), White (black sleeve) to Purple (yellow sleeve), Purple (black sleeve) to Brown (yellow sleeve). Check these 3 different readings of the trigger wires with a digital multimeter and see how you go. Cheers

How to diagnose stator,timer,pwr pak fault no spar

By: on 4 March 2020
always the way. You never have an issue with the thing until you go to sell it. yes thats wright its the dreaded no spark on my 1977 85 hp v4 Johno.The question i have is can you fault find whether its a pwr pak/ timer/stator issue [no spark on all 4 cyl or at 1,2,3,4 on pk] while timer, stator still on motor or will these parts need to be removed?i had another pak and changed it [no telling if it was good] but still no joy surley theres a test for a pwr pak b4 its fitted?.Cleaned every elect connection on motor like new and tested coils [ok].Cannot get in to see anyone until late march and i have a buyer waiting now.Any assistance would be appreciated.Cheers. Oh and can you please explain what a DVA adaptor is ?

Outboard Spares Response
Hi Paul, Thank-you for your patience on this one. No Spark would most likely be stator, ignition switch or pack. Start by disconnecting the stop wire ( Black/Yellow wire) on the powerpack and re-test. If ok, the ignition switch, shift switch or harness has a problem. If this does not fix your issue then I'd suggest disconnecting the yellow wires to the rectifier from the stator. If this resolves your issue then replace the rectifier. 3rd, if you still have a problem check your battery leads and battery voltage as poor voltage to the starter motor may not be allowing the engine to crank over fast enough to generate the desired voltage for the ignition system to function. Last, check your stator output. (brown wire to the brown/yellow wire) you should be getting around 150 to 400V with the DVA meter connected. If you are still having issues, give me a call and I'll help if I can. Cheers

yahama 1992 misfiring and shaking wount go over 18

By: on 3 March 2020
hii have 1992 yahama v4 fouling plugs 2and 4 change fuel pump rebuild carbs need help

Outboard Spares Response
Hi, sounds like either a oil sensor or over heat sensor issue. Do you have any alarms sounding? Pretty sure these models restrict RPM if the oil level is low and also if the engine is over-heating. I'd be checking to ensure that you don't have an overheating issue (check thermostat assembly, relief valve (poppet valve) assembly and possibly your water-pump. If the engine has good water pressure from the tell tail then I'd suggest your problem is (if overheating) thermostat or poppet valve related. If all these check out ok, then you could have a faulty temp sender. It's found on the cylinder head and connects to the CDI Unit. Disconnect it from the CDI unit and see if this fixes the issue. NOTE: This will tell you if you have a faulty sensor OR an overheating issue. You may still have an overheating issue, even if the thermostat assembly and poppet valve seem ok. A build up of salt in the Cylinder head and water jacket cover plate will cause overheating issues too. These would be worth inspecting, even just for preventative maintenance. If none of the above resolves your issue then it could likely be a faulty oil sender in the oil reservoir. See how you go with the above and get back to us if you're still stuck. Cheers

04 mercury 125hp rpm speed issue

By: on 4 February 2020
I have 2004 mercury 125 hp outboard 2+2 motor I've replaced the accelerator pump,check values rebuilt the fuel pump,all new fuel filters,fuel bulb and line,new plugs,rebuilt the carbs did a compression test,marked the prop to see for a spun prop,no clogged exhaust ports still having issues trying to get up to speed at 1800 rpms you can feel the motor shake and run rough but only at 1800 rpms wont get up to speed and plane out max rpms I get out of it is 3800 rpms she fires up right away and idles like a dream the power pack wires were fried i replaced that and still have issues now the rpm gauge has been hit and miss sticking and jumping any ideas thank you for your time!!!

Outboard Spares Response
Hi, Try disconnecting the voltage regulator from the system and re-test. If the problem goes away, replace the voltage regulator. These engines also have a rev limiter (small black or small blue box with about 4 or 5 wires coming out of it) This could also be the issue. I can't recall if there is a test for this part, but if your voltage regulator isn't faulty then the rev limiter would be my next guess. Good Luck

2 stroke 55hp yamaha 2012 /2cyl

By: on 19 January 2020
Started engine up went to my fishing spot switched engine off at the key, when it was time to move on I turned the key at ignition and absolutely nothing starter motor not turning over or nothing, nothing happening completely dead I checked power to alternator checked fuses broken wires found OK, tried to buy pass the ignition and try to start from the starter motor starter motor turns engine over OK but won't crank, there's spark but it won't start,checked neutral switch and cut out switch battery and ignition found OK. Any ideas

Outboard Spares Response
Hi, Sounds to me like the starter relay/solenoid has failed. I would look at testing this and/or replacing it. Cheers

Mercury 2002 40hp 2st 2cyl

By: on 29 October 2019
Only firing on one cylinder. New plugs new coil( not genuine. After market) with 4 pin plug. If I switch coils the other cylinder starts running and the one with new coil stops firing. Could it be faulty new coil, or something else? Thanks

Outboard Spares Response
Hi, If the problem is following the new coil, then I'd guess the new coil is faulty. Cheers

1994 Mercury Tracker 90HP 2-stroke 3 cyl

By: on 28 October 2019
Great site Outboard Spares. Replaced the fuel filter & spark plugs on our 'new to us' Mercury 90hp 3 cyl a few months ago. After at least a dozen hours of operation we removed the plugs to fog the cylinders for winter and noticed that the top two plugs are somewhat blackened and clearly generating some sort of ignition in the cylinder, but the bottom plug is clean as a whistle - looks like the day I put it in. The motor seems to run reasonably well at low RPMs but does not put out as much power as I think it should at higher RPMs and sometimes seems to bog down like it is starved for fuel at higher RPMs. Any suggestion where I should start to diagnose this motor's issues?

Outboard Spares Response
Hi, Around that ERA they moved to a CDM Module assembly on each cylinder instead of a traditional coil. These were/are prone to failing as they age. If it is this type, you could swap the CDM Modules around (move the middle to the bottom and bottom to the middle) and see if you start getting spark on the bottom plug that you were not previously. If the spark does follow the middle CDM then you'll know you have a faulty CDM. The same can be done if you just have standard coils fitted. To me it sounds like this is the issue (coil breaking down under load) given the upper two plugs look like they are firing and the bottom appears like it's not. Good Luck.

2001 Tohatsu 25

By: on 26 October 2019
Hi. I have a starting issue, I’ve replaced solenoid put a new battery in, the starter motor engages but does not turn over. I’ve checked all lines and terminals for corrosion but they are clean. Pull start is fine thankfully but electric start won’t happen. Is it possible faulty ignition switch?

Outboard Spares Response
Hi, Thanks for your inquiry. I'd suggest carefully bypassing the solenoid with a set of jumper leads to the starter motor and see if the starter motor then turns over. If it does, you can assume the battery leads or the solenoid are no good. It could be the ignition switch, but unlikely. The ignition switch just sends 12 volts to the solenoid to open it. If the solenoid is opening for power to go through the solenoid and then the starter is actually trying to crank over, I'd say you have a problem with your leads or the starter motor itself. Good luck. Cheers

97 mercury 175 efi

By: on 24 October 2019
Motor starts no problem and has good spark and compression. Turn it on and it idles pretty good with a small miss but its had it for about a year. Recently though once I take it down the lake say 2 or 3 miles and shut it off it runs fine at high rpms. But once I fire it back up it has a harder time starting usually have to give it gas to start it and to keep it running it will sometimes take off fine but it loses 3 cylinders and just Boggs. But after a minute or so it will take back off firing on all the cylinders then it drops them again. I've went through and check and replaced alot of fuel related parts except got into the fuel injection. Could this be the switch boxes? I read in my manual that the fuel regulator could cause something like that to happen but even with the new regulator it's only running 35 psi when it should be up to 90psi. I'm lost

Outboard Spares Response
Hi, If the fuel pressure should be at 90 PSI then it's possible that the high pressure fuel pump in the VST (vapor separator) needs checking. Otherwise as far as ignition is concerned, yes it does sound awfully like a faulty switchbox or stator coil. I'd be leaning to faulty switch box though as in my experience these type are prone to failing as they get older. Good Luck! cheers.

90 Hp mercury 2 stroke 3 cylinder

By: on 17 October 2019
Motor overfuels and has this coffing sound in the water with no power and when motor idles only 2 of the 3 plugs make a difference but all three have spark but only 2 firing, could this be carburetor issues?? Thanks in advance

Outboard Spares Response
Hi, possibly a carburetor issue. I probably need a bit more information regarding the "no power" and "overfuelling", as in when is the engine overfuelling (RPM range) and when does the engine lack power (RPM Range or throttling onto the plane)? If your carburetors haven't been serviced for a while I'd start with them and then go from there. Cheers

Mercury 2004 50HP 2 stroke outboard

By: on 15 October 2019
had a couple of months of perfect running then last Saturday whilst heading back at the end of days fishing travelling at around 16 knots engine just died stopped dead. checked fuel ok tried re starting and it started but very weak and only ran for 5-10 seconds then cut out this kept going on for an hour or so - on some starts i was able to put it into gear but it would shut down immediately - finally gave up and had to get towed at home have tried and same deal its starts strong but will only idle for seconds and then dies any thought? many thanks in advance alf

Outboard Spares Response
Hi Alf, Hmmm, could be one of 2 things. 1) water/debris in fuel. It could be that you've got to the bottom of your tank (end of the days fishing) and sucked up some water/contaminants in the fuel. Water will always sink to the bottom of the tank as will contaminants. Your engine may just need the filters cleaned or replaced and the carburetors cleaned. 2) Ignition issue. Likely stator. From what you have described it sounds like a faulty stator (if it is not a fuel issue). You'll need a digital multimeter with a DVA adapter to check the stator output. Read between the white wire with green trace and green wire with white trace. With these wires disconnected from the rest of the ignition system you should have between 180 and 400 volts. If you then connect the wires to the rest of the ignition and the reading is lower, then you may have a bad CDM Coil module. Good Luck. Cheers

1994 Johnson 50hp oil injected

By: on 8 October 2019
Hi there, I just picked up a 94’ Lowe pontoon boat and I’m having some issues. When I bought it the owner took me out on the lake and everything was working fine. I took it out on the lake a month later and it started up with the help of a little throttle. After a few minutes at no wake speed it would die but would start back up and die at idle again. Finally got it running decent and it seemed as if it was running degraded on one cylinder. And then finally died and wouldn’t start at all. Took it home and checked it out. Both cylinders #1/#2 have 120 compression and were getting spark. I noticed the plugs were fouled which looked like it was running rich so I replaced the spark plugs and cleaned the carbs. Tried cranking again and nothing. I noticed that when I pulled the plugs and cranked it to clean it out it was blowing a lot of oil out of the bottom cylinder. I’ve read that the oil pump plug can come loose with the vro pumps if I’m not mistaken and leak oil into the bottom cylinder possibly causing this? Any help?

Outboard Spares Response
Hi, I'd say that while the engine has been sitting without use for over that month period the VRO has leeched oil into the bores. You may have to use a fair bit of cold start (neutral throttle lever) and fuel priming through your ignition switch to get it started if the engine is really oiled up. I'd say this is all it is. If it were me, i'd disconnect the oil injection side of the pump and just pre-mix the fuel and oil at 50:1. VRO pumps were typically unreliable and the best insurance was to just mix your own oil and fuel and be done with it. Good Luck

1990 Yamaha 90 2 stroke

By: on 7 October 2019
Hard starting. Breaks down around 1900 rpms. Runs fine on higher rpms. Seems to be bottom cylinder not firing properly. Changed coil and cleaned carbs. Compression is 120 on all 3 cylinders. I pulled the plug wire on top and middle cylinder at 1900 rpms and each stalled the motor. When I pulled bottom cylinder wire motor still run.

Outboard Spares Response
Hi, I would try a spark test with a spark tester and see if the bottom cylinder is definitely not firing. I would then swap the coil primary wires to the CDI Unit (change their positions, number 3 to number 1, number 2 to number 3 etc) and see if the problem stays on the bottom cylinder or follows the CDI Unit Output position on the CDI Unit. If it does follow the CDI Unit Output position, then you may have a faulty CDI unit, or a faulty Timer Base. To confirm if it is a faulty timer base, you will want to test the timer base wires connecting to the CDI unit. Ensure voltage is even across the 3 input wires. Good Luck. Cheers

1991 Evinrude 200hp

By: on 30 September 2019
I was driving it running about 45mph and the motor just shut off. It would start up then die now it has no spark. I disconnected the black and yellow wire from the power pack (the plug) then I turn the key and it fires right up and runs but under load it only goes 6mph like it’s limiting the amount of power. I replaced the ignition switch and still did the same thing when the black and yellow wire is disconnected from power pack the engine runs just can’t shut it off but when it plugged in there is no spark?? I just noticed the rectifier is burnt but I was told that would not keep it from running and the kill switch has continuity I also check the shift switch and it has continuity please HELP!!! I’m so fustrated...

Outboard Spares Response
Hi, I would disconnect the yellow wires from the rectifier and re-test the sytem. I'm confident from what you have said that this will be your problem. Cheers

92 johnson 115 with vro

By: on 27 September 2019
Motor starts fine and idles good. I take it to full throttle and it runs smooth for about 5 seconds and then it bogs down or lurches. I take throttle back to slow idle for 10 seconds go back to full throttle runs smooth for 5 seconds bogs down again.

Outboard Spares Response
Hi, Thanks for getting in touch. It is hard to say exactly what the problem may be. From what you've said about it bogging down after full throttle I'd be thinking it's not getting enough fuel at WOT. This could be because of the VRO system or perhaps a restriction in the fuel system somewhere. Alternatively it could be an ignition issue, possibly stator or pack but very hard to determine with the limited information at hand. Try the fuel system first and see how you go, in particular check there are no blockages in the tank breather lines. Good Luck.

1985 Johnson 50hp VRO

By: on 16 September 2019
Hi, Just got a second hand boat. The engine jumps beautifully and goes great. The only problem is it seems when I stop the engine gets flooded. Could this be due to the location of the red choke switch internally? I believe it was open entirely. I just don’t want to take out again until rectified as it would take about ten minutes of clearance time to get going again.

Outboard Spares Response
Hi, To my knowledge the red valve on the primer solenoid can cause flooding if left in the open position as it is effectively a choke. Cheers

1977 70hp No Spark When Cool

By: on 14 September 2019
With Fall arriving and cooler weather in northern Maine my 1977 3 cylinder Evinrude quite often does not get a spark on any cylinder sparkplug in the morning. I have tightened all the wires on the power pack. I have discovered on a sunny day if I take the hood off the engine and expose the powerpack to sunlight for an hour or so I do get spark to all cylinders and the engine runs fine at all speeds around the lake. I have also determined on a cool cloudy day when I don't get any spark that if I use a heat gun and focus the hot air on the power pack for about 15 seconds that all the plugs get spark and the engine runs normally out on the lake for extended periods. Thus far I have not been able to find any mention or resolution of this problem and am reluctant to purchase a new powerpack until I am reasonably certain it will resolve the problem.

Outboard Spares Response
Hi, I think you have figured out your problem. Faulty Power-pack. Everything you've done points to that being the problem. You could test the stator with a digital multimeter and DVA adaptor to see if the output of the stator is at least 150 to 400 Volts, but I honestly think what you have done is quite ingenious and I'd be certain a new power-pack will fix your issue. Cheers

30 hp 2 stroke yamaha outboard

By: on 12 September 2019
At initial start-up, everything runs fine. I can run the outboard for 2-3 hours with no loss of speed or power, but if I shut the motor down or if it runs out of gas, I will have to wait for 20-30 minutes before it will restart. Runs good on all cylinders. Any thoughts on what to check for?

Outboard Spares Response
Hmmm, interesting! Initially, I was thinking your engine was simply flooding but if it does the same thing when it runs out of gas then it may not be....however, is it an oil injected model?? If it is it could be that your engine is over oiling and this basically means your spark plugs may be fouled due to all the extra oil. Check the plastic "joint link" fitting that is on the end of the rod that runs between the oil pump and the carburetor (on the oil pump end). If this connector is cracked or damaged, it could be causing your oil pump to "default" to full advance which means your engine will constantly be running at it's maximum oil delivery. If that's the problem it's an $11 part and all fixed in 5 mins. Hoping this is the problem. Let us know how you go. Cheers

1989 90hp Johnson 2st V4. Missing when warms up

By: on 9 September 2019
Only when it warms up, either 45 min normal running or 20 min towing tubes. Engine starts missing. Replaced plugs and was a little better for a short time. Replaced coil packs (with a loan pack) and no change. Checked HT leads with meter and all good. Checked fuel breather not blocked. It is not limp mode (I don't think) as no alarm goes off. Runs ok at low revs then misses when cranked up

Outboard Spares Response
HI, When you say coil packs I assume you mean coils? I'd be checking the power-pack/s. Power-packs tend to start failing as the engine heats up when they are nearing the end of their life. Power-packs will also cause a miss. The other thing that will cause a miss is simply an engine that needs the mixture screws tuned on the carbs. However, if you suspect that it's more than a simple carburetor adjustment then I'd be looking at the aforementioned scenario of a faulty power-pack. Cheers

bass tracker won't start.

By: on 1 September 2019
Hi I installed a new switch on 97 force outboard. when I tried to start it turned over 4 or 5 times it was firing;then turned the switch nothing , I checked the starter it was engaged with the flywheel will not drop below the flywheel but both will turn by hand.

Outboard Spares Response
Hi, I'm assuming you are referring to an ignition switch. I'd be checking your battery voltage as it could be that you just have low battery voltage and this is causing the starter motor to not turn over fast enough. It could also be old battery leads. IF, the engine is now not cranking at all (even with a fully charged battery and good battery leads) then I'd check the way you've wired in the new switch. NOTE: It could also be a faulty starter solenoid OR tired starter motor, but I'd check the previously mentioned suggestions first. Cheers

1990 8 hp Johnson, no spark to top cylinder

By: on 31 August 2019
Hello, I have an 8 hp Johnson,circa 1990. Its only running on the bottom cylinder. I put an inline spark tester in place, and the top cylinder is not getting any spark. I have replaced the coil with another one from a parts engine and that didnt make a difference. I have swapped plug wires and that also didnt make a difference. I did order a new CDI that I put in place, but with the new CDI, i didnt get spark in either cylinder so im sending the CDI back, but just wondering if this could be anything other than a bad CDI?

Outboard Spares Response
Hi, Thanks for getting in touch. First I'd be disconnecting the stop switch (black wire with yellow trace) from the circuit and re-testing. It could be you have a faulty stop switch causing you grief. If this doesn't fix the problem then I'd consider the stator is potentially faulty. I'd be testing it's output using a digital multimeter with a DVA adaptor. I think you should be getting between 150 to 400 Volts between the brown and brown and yellow wires. Hopefully this helps. Cheers

1989 Yamaha 175 precision blend v6

By: on 27 August 2019
Port side bank (all 3) has no spark. Coil packs are good (swapped with starboard) and wires ohm out to terminals. The Yamaha Control Unit (icu-10) has odd ohm readings based on a generic manual. If the icu-10 is faulty, would it cause 3 cylinders on port side not to fire? Not sure where to check next. Any suggestions?

Outboard Spares Response
Hi, Ok I'd be swapping the stator wires over on the CDI Unit and conducting another test. From memory you'll be swapping the blue and red wires over from their positions on the CDI Unit. These wires are what fire the port or starboard bank. If you find that the problem now shifts to the starboard bank, you most likely have a faulty stator. Also, check the engine is not over-heating and causing the CDI unit to limit RPM. You can disconnect the temperature sender wire and see if this helps. You could also disconnect the stop wire (white wire) from the CDI Unit and see if this makes a difference also. My gut feeling is that your stator is faulty, I may be wrong.... Cheers

98model 25 nissan c3

By: on 25 August 2019
Ok I bought this motor knowing it had a problem . Problem is when trying to start its backfiring and when and if it does start its still popping and backfiring will only run for a short min before it stalls and sounds really weak

Outboard Spares Response
Hi, Ok, so I'd think timing is the issue, or some kind of fault in the ignition. Is the engine running a rectifier? If so I'd disconnect it and see if the problem goes away. Secondly, disconnect the stop wire from the kill switch/stop switch. See if the problem goes away. Third, could be a faulty coil OR CDI unit. I actually don't have any testing procedures for these components. If you can get your hands on a second hand CDI, or coil it may be worth while. Cheers

1985 90hp yamaha

By: on 22 August 2019
Starts and idles just fine. Put the boat in gear and start to go revs up to around 2000 rpm then shakes and misses pull back to idle runs fine. Idle it in gear for 10 to 15 minutes shut it off 10 minutes runs fine the rest of the day. Clean carbs couple of times put new fuel pump on oil gauge works grounded temp senser alarm go's off help

Outboard Spares Response
Hi, sounds like it could be fuel or ignition timing. If after cleaning the carbs it is still having the same problem then I'd think potential ignition problem. Try disconnecting the stator wires that run to the rectifier and re-test. If the problem disappears your rectifier needs replacing. Otherwise, check all linkages between the carburetors, throttle and timer base. These engines have plastic joint link fittings that sometimes crack and cause linkages to slip, which may be causing the timing not to advance when it should. Try these things and see how you go. Cheers

81 70 horse evinrude can't get over 3,000

20 August 2019
I've changed coils plugs rectifier checked timming carbs all question is go and use trim with moter running at 3g voltage will drop to 12 an slowly creep back to 12.5 when I could get it to 4500 rpms voltage would jump 13.5 is it possible for ignition running off battery and charging coils keeping battery up just enough?

Outboard Spares Response
Hi, to answer your question, I don't think so. You could try changing over the battery and seeing if this fixes anything but I'd say it's unlikely. I'd be now looking at the following. 1) Check all linkages between the throttle, carburetor and timer base. Make sure that all linkages are activating as they should and that none of the plastic end fittings on the small control rods are cracked or broken. 2) Check if the temperature sender in the cylinder head connects to the power-pack. If it does, disconnect it and see if the engine now runs properly. If it does, your engine either has an overheating issue (faulty thermostat, waterpump, blocked head, etc) OR a faulty temp sender. 3) Check stator output. Ensure stator voltage output is between 150 and 400 Volts. You will need a DVA meter for this. See how you go with this. Cheers

1989-1991 evinrude 175hp 2 stroke VRO no spark on

By: on 19 August 2019
hi, tested coils, leads and plugs on other known working cylinders without fault to any of those parts. looking for accurate diagnostic steps/specs to move forward. the CDI is a sealed unit. any accurate info on testing the cdi, stator and trigger would be greatly appreciated. thankyou

Outboard Spares Response
HI, More information would be great. What is your engine doing or not doing? Cheers

1981 evinrude E70ELCIH

By: on 19 August 2019
I have put new plugs coils rectifier clean carbs I can't get to go past 3000 RPMs check timing 15 degrees top dead center adenoidal idling around 1100 RPMs put in gear wide open throttle 2000 RPMs I use trim voltage drops to 12 slowly creeps up to 12.5 and we'll stay there when I did get it to go over 3000 I would hate about 45,000 RPMs voltage would be 13 / 13.5 by me not getting over 3000 RPM would that be caused by a faulty stator would the ignition system be running off the battery and charging system is enough to keep the battery charged is that possible

Outboard Spares Response
Hi, Thanks for getting in touch. A couple of things spring to mind. Check the nozzle gasket on the carburetor is fitted. I have had these in the past where it's been left off during the service of the carburetor and subsequently won't let the engine perform. Also, try priming the primer fuel bulb on the fuel line while trying to get above the 3000 RPM to see if that makes a difference, Could be the fuel pump has the problem. Have you changed propellers? If you've fitted a propeller that is too large (in pitch and diameter) then the engine may be having trouble spinning that size propeller on your vessel size and weight. Lastly, have you checked spark? I know you have changed the plugs, coils and rectifier, but are you getting spark on all 3 cylinders? Feel free to shoot me an email if none of the above gets you out of strife. Cheers

2012 50hp 2 stroke

By: on 18 August 2019
Gday, Please help..... Went to take the family out for a run in our peace of joy. Started beautifully using choke for cold start off the trailer to the pontoon, turned her off to park the car. Started ok with family aboard, motor run out as soon as left the pontoon and not able to re-start. At first when turn the key engine would try kicking but nothing, very quickly it sounded like dead battery. Got boat home and checked battery, battery 12.54 and good. Tried starting at home, when turned the key and watching starter move up to turn fly wheel slightly then stop, appears to be electrical/ignition issue...... any ideas or suggestions please?

Outboard Spares Response
Hi, Sounds like battery to me. 12.54 resting isn't that great. I'd be putting the battery on a charge and then trying again. If the engine then fires up ok, It may be your battery is on the way out and needs replacing, especially if it is not holding charge. See how you go. Cheers

79 johnson V4 85hp Constant miss through rpm

By: on 18 August 2019
I have a 85hp V4 that keeps a constant miss through all RPMs and idle. Worrying in time it can damage my lower unit. Have changed and gapped plugs but is hard to figure out where it's coming from.

Outboard Spares Response
Hi, It could be a few things. Try disconnecting the yellow stator wires that connect to the rectifier and test engine. A faulty rectifier will cause a miss across most of the RPM range. A cracked or broken flywheel magnet could cause a miss through the RPM range, as could a faulty ignition coil. On the other hand, it may not be ignition. If the engine is sucking in air or the carburetor mixture screws are not set properly then this could also cause a miss. Try the ignition first as I've suggested. Otherwise, maybe give the carbies a service and tune. Cheers

1998 50hp johnson outboard won't fire?

By: on 16 August 2019
we have a 1998 50hp johnson that wont fire. We were out in lake running normal and it made a funny rough noise and quit running. It had to be towed. We replaced the power pack, coil and new plugs. Still won't fire. What's next??? We are not boat mechanics but tit didn't seem hard!

Outboard Spares Response
Hi, Thanks for getting in touch. If the engine is turning over (not seized) and now won't start and there was a "funny rough noise" then I would be removing the flywheel and checking for a damaged magnet. If you have a damaged flywheel magnet this would explain the rough noise and subsequent issue with the engine not firing. Also, check your stator is not damaged as a broken magnet from the flywheel may have caused damaged to your stator. Try this and see how you go! Cheers

2000 35 johnson ooutboard

By: on 10 August 2019
kicks over & runs good .but every now & then just cranks over & wont start .then will start after a few goes.flushed motor other day ,stopped it & tried to start straight away & took a few goes to kick over then runs happydays?

Outboard Spares Response
HI, I'm assuming this is a 3 cylinder model. These engines had a number of issues with the powerpacks. I'd first start by disconnecting the stop wire from the powerpack plug (Black wire with yellow trace). Once disconnected check to see if the engine experiences the same problems. Remember, you won't be able to stop the engine with the key switch unless you re-connect the wire. If the problem is now resolved then the ignition switch or harness has a problem. I'm just guessing that it is a spark issue, there is a chance it could also be fuel related but on the surface it sounds like a faulty power-pack. Cheers

2002 yamaha 90hp top cylinder stalls and dies afte

By: on 9 August 2019
hello. hope you can help me. I have a 90hp yamaha 2 stroke. All 3 cylinders have 115 compression, spark plugs good, and carbs rebuilt, cleaned and getting fuel. all 3 cylinders seem to get sparks but the top one can not run by itself whereas 2nd and 3rd cylinders run strong alone. Top cylinder stalls and dies after few seconds. In the water RPM doesn't past 4000 on WOT. I believe the top cylinder is preventing the RPM from going higher. Been dealing with this for months and my mechanic scratching his head. :T Thanks in advance.

Outboard Spares Response
Hi, So a couple of suggestions. Have you tried switching coils around to see if the problem follows a faulty coil? Have you tried swapping propellers to see if it is a propeller issue, E.G: trying to spin a 21 pitch when should be a 17 pitch..... Also, check all linkages to ensure that there are no cracked plastic linkage ends that are preventing the throttle and/or timing from achieving full movement. Maybe also try priming the primer bulb while underway to see if this changes things. You could have a faulty fuel pump, although I'm not convinced this is the case but worth trying. The other thing is that these engines run a CDI Unit with an advance lever. This adjusts timing as the throttle increases. I would be checking this as it could be the source of your issue, presuming that the problem has just appeared out of nowhere and not straight after works done on the engine. It is not un-common for this lever to "wear" and cause ignition problems. I'd check the linkage going to this advance lever for cracks in case it is a simple cracked fitting causing dramas. I hope this helps point you in the right direction. Cheers

40hp tohatsu 2stroke no power under load

By: on 31 July 2019
Was full noise in the creek then suddenly lost power and runs at 10kmh full throttle any ideas of what my issue could be

Outboard Spares Response
Hi, Is the engine RPM still high but you have little speed? (potential slipping propeller bush) Or is the engine not achieving high RPM anymore? (Potential rectifier, stator or fuel issue) If you can supply some more details we'll do our best to assist. Cheers

why my johnson 1994 150 2 stroke fast strike shut

By: on 31 July 2019
run good till it warms up than just shuts down

Outboard Spares Response
Hi, Thanks for getting in touch. Have you checked for spark when the failure occurs? Meaning, have you tried with a spark tester? Also, is the engine achieving full RPM or are you warming it up at idle and then it's stalling when you increase RPM? Try and get back to us with a few more details and we'll do our best to help. Cheers

1997 Evinrude E115ELEUC misses at WOT

By: on 31 July 2019
Hi, i’m chasing a problem or multiple problems with maybe you could help. Bought this motor two years ago. Starts fine, idle fine but won’t go over 3900 revs. If I push the trottle over that point it begins to miss and it get worst if push it all the way. I was thinking of gaz problem do I cleaned the carbs no change, I found that the diaphram was cracked so I rebuilded the fuel pump, no change I bypassed the oil pump and mixed my gaz cause it was smoking a lot too no change. Change the plugs. Then I removed the plug wires one by one and on one cylinder the fire was poor and intermittent so I switched the coils and the problem stayed on the same cylinder so I changed the power pack and no change. Before changing the power pack I checked the compression it is 115-118-118-120. Since I changed the power pack there is a vibration like the motor is running on three cylinders. Any ideas ?

Outboard Spares Response
Hi, So it could be a whole bunch of things. My first question is, what is your propeller pitch? Is it as simple as having a prop that is too big and won't allow the engine to reach its appropriate RPM? Second, try disconnecting the stop circuit from the power-pack. It is the black wire with the yellow stripe. If the engine now runs well you either have a problem with the stop-switch, shift switch or harness. Third, try changing the spark plug leads around. I know you switched the coils, but try the leads, it could be a lead shorting to ground. Let us know how you go with the above. Cheers

Yamaha 20A 2 stroke

By: on 29 July 2019
Having a struggle with this one. It will start and run well. Ticking over with no problem. It revs well and doesn't miss. After about 10mins, the engine just dies. Trying to catch it by giving it a bit of throttle or by giving it a bit of choke has not effect. Once it stops, it won't re-start for about 45 mins. It starts with no throttle or choke. Any ideas?

Outboard Spares Response
Hi, ok so, first things first. Check that the engine isn't overheating. Assuming it is pumping plenty of water, I would pull the thermostat out and check it is operational. Just place it in a mug and pour some boiling water on it and make sure it opens. Next, assuming the thermostat is working correctly, I'd be running the engine as you normally would preferably close enough to shore that you can easily get back to land, to then conduct a spark test (or just back your boat down at the ramp on a quiet day and run it on the trailer). Preferably, you want to have a spark tester as this is the safest way to check the engine does or does not have spark. If you find the engine does have spark after it stops, I'd be looking towards a fuel issue. Possibly as simple as blocked breather on the fuel tank or faulty primer bulb, or even a worn fuel pump. If the engine doesn't have spark, I'd be looking at the CDI unit. Faulty CDI Units will give grief when the temperature around them increases and the unit gets hot. This could also be the issue. Hopefully one of the suggestions is enough to point you in the right direction to solving this problem. Cheers

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