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 (45)

92 Yamaha 200

By: on 5 April 2019
No spark on one plug spark plug coil was bad change it new plug still no fire

Outboard Spares Response
HI, Did you change the coil or the plug? You could switch the coils around and see if the problem stays on the same cylinder or follows the coil. If it follows the coil then replace the coil. If it stays on the same cylinder then I would consider the CDI unit or timer base has a fault. You could check the output of the timer base to the CDI unit and see if the voltage across the wires is equal. Then check the Coil side of the CDI Unit for output. If you find the input to the CDI unit from the timer base is ok BUT the output from the CDI Unit to the coil is inconsistent then replace the CDI Unit. If its the opposite and the input to the CDI unit is varied, then I'd replace the timer base. I hope this helps. Cheers

1990 Johnson 200hp 2 to 3 cylinders firing

By: on 3 April 2019
Hello, I recently picked up a very clean 1990 Johnson 200hp outboard. I was told that the flywheel (all magnets look to be in good shape) and starter were replaced by the previous owner. I have been testing the ignition system and have found that the top two cylinders will fire and occasionally the port bottom cylinder will fire (using a spark tester). I have cleaned all the coils and switched them around with the same result. I am also using a charged marine battery with the charger hooked up. I have all the spark plugs removed with the exception of the test cylinder for higher rpm testing. Using my fluke multimeter I was able to test the resistance of the stator and it seems within spec. Brown to brown/yellow is 780 ohms and orange to orange/black is 93 ohms. Moving on to testing voltage with a DVA adapter, I was only able to ever get 40v AC when testing from the wires that feed the power pack (feeds all 6 coils on this engine). It seems that these readings would indicate a bad stator, but would a power pack receiving only 40v generate any spark on any cylinder? Thanks for the informative article.

Outboard Spares Response
Hi, Thanks for your question and the data supplied. It definitely sounds like the stator is bad. The Ohms reading from the Brown to Brown/Yellow should be between 900 and 1100 so 780 ohms seems low. Also, you should be getting at least 100V from the stator to the power-pack, anything lower than this is out of factory specification. Looks like you've tested everything the correct way. Replace the stator and hopefully it will be happy days! Cheers

Yamaha 2001 150FETO 2 stroke electrical trouble

By: on 2 April 2019
Hi there, Fairly regularly, and usually while starting or flushing engine after use, all electrical power vanishes, only to reappear again a few minutes later. When running at idle, the engine will sometimes quit, at which time all electrical power disappears, again to reappear a few minutes later. Does that sound like an ignition switch issue to you? Thanks!

Outboard Spares Response
Hi, are you sure there is no spark when the engine stops, or are you presuming it has lost spark? You could disconnect the stop wire and test the system to see if this changes things, obviously remembering that you'll need to have the engine running in a large drum, or at the boat ramp so you don't risk cooking your engine. The white wire is generally the stop wire on Yamaha and you'd disconnect it from the CDI unit. Otherwise it could be a fuel issue where it is over-fueling at idle...possibly. Hard to say but when in doubt take it to a registered and qualified technician. Cheers

1986 Yamaha 115 2 stroke ETLJ no spark

By: on 2 April 2019
Outboard was running, idling while beached, while we were getting ready to head back to boat ramp and then it died. I checked fuel, that was fine. I checked for spark and had no spark. We tried removing white wire to eliminate ignition switch and safety lanyard switch and still had no spark. I checked fuses and all looked good. I had some cell service and found on google that there was supposed to be some voltage going through the trigger wires on the CDI. I had a wire and ran 12v to one of the 4 trigger wires. It immediately sparked and turned the engine a quarter turn as there was still fuel in the cylinder from trying to start. I then tried to start it and it fired right up and we got the boat ramp and put it on the trailer. Got home and it fired up again with the earmuffs on it. I'm not sure where to start here. I don't want to get stuck next time we goto the lake. Thanks in advance for your help.

Outboard Spares Response
Hi, that's a tricky one, largely due to the age of the engine and things will start to breakdown on an engine that age. Possibly the stator has an issue. I'd check the stator output and timer base output with a Multimeter and DVA adaptor. You should have 2.5 volts minimum coming from the timer base wires using the DVA and 280-430 ohms. The brown stator wire reading to the red stator wire should have a minimum of 85 volts and the blue stator wire reading to the black/red stator wire should have 16 volts minimum. If this checks out all ok it could be the CDI Unit, provided you have tested the stop circuit accurately. I hope this helps. Cheers

2004 600hrs 90 Yamaha 2 stoke oil injection limp

By: on 19 March 2019
Hi, have issue with 90 Yamaha, runs fine 3/4 but when open up it goes into limp mode for like 30 sec and the I can take off again. Will run all day only when open up. Changed impeller Changed spark plugs Check thermostat working Still does it. Now cleaning out cooling system on side of bloke wasn’t too bad. Will look at disconnecting heat sensor to see if it the oil alarm? Had outboard 3-4yrs now and first issue I’ve had with it. Boat is. 5m wahoo fibreglass running 19p stainless. If anyone had this issue would like to know how to fix it. Cheers

Outboard Spares Response
Hi, It's hard to say what the problem is without more information. Overheating is probably the most obvious. Is the alarm sounding? If it is a constant tone then it is most likely the reason for the engine going into limp mode. At your engine age, the cylinder head and cover plate are probably due to come off and be cleaned out. This would be my suggestion. Cheers

Need help no spark 94 mariner 25hp

By: on 9 March 2019
Hello I’m need some help I have no spark st the plugs, replaced the coils, cables, spark plugs engine turns but no spark coming out of the plugs. What should I check or test?

Outboard Spares Response
Hi, If you have not already, disconnect the stop switch wires from the power pack and re-test. You could have a short to ground in the stop circuit. Otherwise, check the stator for output with a Multimeter and DVA adaptor (if you can get your hands on one). If that all looks ok, it is possibly the switch box which are prone to failing on this model. I hope this helps. Cheers

2001 Johnson 60 hp has no spark

By: on 7 March 2019
Here's a curly one. For a long time now I been battling with a no spark issue. Initially,if I was to start my outboard every 2 or 3 days I would not have a problem. If I left it for a couple of weeks, it would take quite a while for the spark to eventually arrive. Once that happen, all was good. I eventually went and changed the CDI Pack over and tried a new one as a process of elimination, and there was spark immediately. Just to be sure, I installed the old CDI back on and...……...I had spark again. Really confused me, because now I was not convinced that the CDI was the problem. It was a CDI Electronics 113-4808 and looked fairly new. Everything went fine for a few months, and then the problem returned. I did not have access to DVA meter...….so I took it to a Marine Tech who advised that there was no signal from the Timer Base......assume its faulty. So, I purchased a used Timer Base and Stator and replaced them both. But still had no spark. Stator produced 208 Volts from the Brown to Brown/Yellow wires at cranking speed(800rpm) on a Multimeter set to A/C Volts, and 104 Volts on the Orange to Orange/Black wires. Both appear to be in spec. Timer Base resistance on the White to White/Black wire is 450 Ohms, and appears to be within spec as well. I am now waiting on a good used CDI to arrive so I can fit and try again. My concern is...…...if the replacement Power Pack produces spark, and I replace the old one(like before) and everything is ok again......what else should I be looking for, and, can both Timer Base and CDI cause each other to fail? Thanks

Outboard Spares Response
Hi, Thanks for you question. It is really common for this particular ignition system to become compromised by a faulty Timer Base (trigger) shorting to ground. I've had numerous trade and retail customers fit new Powerpacks (CDI units) to have them run for a short period and then stop. The problem is when a faulty Timer Base shorts to ground it can compromise the SCR's in the Powerpack. So your old Timer Base may be faulty. So when replacing a Powerpack on this model I always suggest changing the Timer Base at the same time so you don't end up with a bunch of Powerpacks that don't work. I hope this helps. Cheers

1995 Mariner 115

By: on 24 February 2019
The motor operated fine for a day on the water. Pull the boat on to the trailer, take her home go to do my rinse down and now she won’t start. It will turn over but not fire up I have checked for spark and I have no spark I have reached a point that I’m unsure what to check next.

Outboard Spares Response
HI, Thanks for your question. First and foremost have you checked that the kill-lanyard (safety lanyard) is connected to the switch on the control box (or dash if mounted there)? If it is connected, then just check that the engine is not in-gear by moving the control box lever forward and then back to neutral. These engines have a switch against the shift rail which won't allow the engine to fire if it thinks the engine is in-gear. Also visually inspect this switch (it's where the control cable ends sit on/in the outboard) to make sure it is not cracked or damaged, or additionally that the switch isn't sticking. This is what I would check. I hope this helps. Cheers

70 hp Tohatsu 2 cylinder Spark Gone

By: on 22 February 2019
Gday, have mid to late 90s Tohatsu 70 hp 2 cyl with no spark, not knowing much about the Hatsus where would be the best place to start, I could take a punt and say the stator , failing that trigger and or the powerpack

Outboard Spares Response
Hi, Thanks for your question. I'll be honest and say that I'm not that experienced on Tohatsu ignitions, however, I assume it will be relatively similar to other Japanese engine brands. I'd test the stop circuit first for a fault. These should be the black and brown wires going to the CDI unit from the control box. If then the spark returns, check the stop circuit for a fault. Otherwise I'd check the exciter (stator) and pulsar (trigger) coils. Using a DVA I'd check output of the exciter coil. I hope this helps. Cheers

1988 Yamaha 150 2 stroke no fire port bank

By: on 22 February 2019
I have an electrical issue. Cylinders 2 4 6 have around 60-70 volts when tested on DVA. Cylinders 1,3,5 have 150 volts. Swapped stator, trigger and CDI from spare parts engine as well as ohm tested all coils. Still same problem on the 2,4, & 6. Compression is 115 across the board. Please advise what I should be looking at ?

Outboard Spares Response
Hi, Thanks for getting in touch. I'd be looking at disconnecting the pink wire to the CDI unit and re-testing for spark. If spark returns, it could be that you have a faulty temperature sender which is causing the SAFE mode to kick in which limits RPM. From memory it does this by cutting out 3 cylinders. Otherwise, check engine oil level on the engine mounted oil bottle or that the sender in the tank isn't faulty. This could also be causing SAFE to kick in. I hope this helps. Cheers

1988 Yamaha 150 2 stroke no fire port bank

By: on 22 February 2019
I have an electrical issue. Cylinders 2 4 6 have around 60-70 volts when tested on DVA. Cylinders 1,3,5 have 150 volts. Swapped stator, trigger and CDI from spare parts engine as well as ohm tested all coils. Still same problem on the 2,4, & 6. Compression is 115 across the board. Please advise what I should be looking at ?

Outboard Spares Response
Hi, thanks for your question. It could be that the engine is going into safe mode and limiting the RPM by cutting out 3 cylinders (from memory, I think this is how SAFE works). You will want to disconnect the pink wire to the CDI unit. If the engine now runs properly then you will need to check the overheat sensor (make sure it's not faulty or earthing to ground) and the oil level in the oil tank on the engine. I hope this helps you diagnose the issue. Cheers

G'day... 78 Mercury 1150, 6cyl, starter motor cant

By: on 16 February 2019
Hi, I have a 1978 mercury 2 stroke, 6cyl, 1150 (model: 8054803) Seems to have all original parts, I got it started once, I have been trying to work out why the starter motor cant turn the flywheel any more than a few inches at a time, power is ok, cables n connections are ok, starter works as it should, but it seems the flywheel is just too tough for the starter to turn... voltage at (dual) battery whilst turning the key drops from 12.5 to 11.1V voltage at starter (under load) whilst turning key drops to 0.6V voltage at starter (no load) whilst turning key steady at about 12.2V Do you have any suggestions? TIA

Outboard Spares Response
Hi, Thanks for getting in touch. Ok, so all original could be a couple of things. 1) Battery leads in poor condition. Check the leads do not feel stiff in areas. It could be that they need replacing. 2) Run direct power to the starter motor with a good set of battery leads straight from the battery. If the starter cranks over then you'll know it's something in-between that's causing the issue such as solenoid, leads, earth, etc. 3) Possible faulty starter motor. Remove and inspect internal components such as brushes, armature, magnets, etc. I hope this helps. Cheers

1978 Johnson 115 v4 bottom starboard cylinder not

By: on 16 February 2019
Bottom starboard cylinder has spark, good compression but will not fire. New power packs, new coils, new plugs, and carbs have been rebuilt recently. I am getting spark jumping a 7/16” gap. Other 3 cylinders working properly. Any ideas??

Outboard Spares Response
Hi, Thanks for your question. It could be a couple of things. 1) Timing. I'd be checking that the timing has been set up properly. It may not be firing as it should be. If this looks ok then it could be 2) Reeds. Check the one for that cylinder is not damaged. It may not be drawing fuel through to that cylinder as it should be. I hope this helps. Cheers

02 self mixing Yamaha 2stroke 60

By: on 7 January 2019
Motor runs fine on idle and 1/2-3/4 throttle on when I open it up I goes alright for 10 mins but then sounds like it's fouling up or misfireing go back to 3/4 throttle and it will go all day fine but if I go full throttle it sound like it will slowly die and help would be grateful

Outboard Spares Response
Hi, Thanks for your question. I would think you've got a timing issue or a propping issue. I'd be checking what RPM you are pulling at Wide Open Throttle and checking that this is within the manufacturers specifications. Most 2 stroke outboards have a max RPM of 6000 (which is what I think yours is). You'll want your tachometer to read under this. If this isn't the issue, I'd be checking the timing and you may be best to do this through a outboard technician if you're not confident doing it yourself. I hope this helps. Cheers

6hp Mariner stopping

By: on 6 January 2019
Hi Starts fine 1st pull when at full throttle though it kicks and stops running with a sound of clicking till I put it into neutral. When not at full throttle runs seemlessly no issues any thoughts? Stops very suddenly 1st time thought I had something the motor kicked up so violently. Appreciate any help. Thx

Outboard Spares Response
Hi, It's hard to say but I think this would be a timing issue. The clicking after it stops will probably be the gearbox chattering until the engine is in neutral. I hope this helps. Cheers

1977 Evinrude No spark on 3rd (bottom) cylinder

By: on 5 January 2019
Hi I have a 1977 75hp Evinrude an I’m not getting any spark on the bottom cylinder, I’ve changed the coil and the CDI unit an still nothing. I’m wondering if it’s possible a faulty CDI maybe, i changed the wiring around so the positive off the new coil (cyl3) ) ran into the positive section of the cdi box that would normally be for cyl2 an the coil fired an I got spark. When I changed the wiring back to normally put the positive from cyl3 coil into the right section of the cdi box I had nothing to that cylinder again. Is there a stop switch for each cylinder separately or could it be a bad outlet point for cyl 3 in the power pack. Bearing in mind that this is a new powerpack

Outboard Spares Response
Hi, Thanks for your inquiry. Based on what you have done and said I think your problem will be the timer base under the flywheel. A word of warning though. A bad timer base will destroy a powerpack. I have had Marine Dealers come to me having installed 3 new powerpacks only to find they've all blown due to a faulty/bad Timer Base shorting to ground. Basically, you could install the new timer base and find that the new pack you've just installed is ruined and it may need replacing again. I hope this helps (even though it may be an expensive fix).

2 stroke 90 hp Yamaha stopped while running

By: on 19 December 2018
My boat got 2 stroke 90 hp Yamaha. I was out in bay fishing. As it was running, motor shut off itself in middle of water. Tried to start, it cranks but doesn’t start. Towed it back, got home. And after playing around for a while and battery charged ( it was flat after trying for a while in water ) it started again. It’s fine now but question is would that happen again? What was it ?

Outboard Spares Response
Hi, It's hard to say what the problem was, but to me it sounds like a possible fuel issue. I'd be checking your breathers on the fuel tank or it could be a partially blocked fuel pick-up. So what I'm thinking is the engine has fuel and is running but then possibly has a breather (or fuel pick-up) issue so this creates a vacuum in the system and starves the engine of fuel. Obviously you try to start it and doesn't fire as the vacuum still exists. You get towed back home which gives the vacuum time to release and that's why it starts again when you get home... Just a theory. I hope this helps. Cheers

1988 Mercury 100 2 stroke outboard (4 cylinder), i

By: on 18 December 2018
Hi! I was reading the CDI Electronics Troubleshooting Guide you linked to above to test my 1988 Mercury 100 4 cylinder 2 stroke outboard. First let me describe the problem. It will start right up and run at 2500 rpm all day. But get it up to full throttle (or even 3500 ish) and it will run fine for around 10 seconds or so (enough to get on plane and up to about 40mph) and then just cuts out suddenly like you turned the key off. It will start right back up fine, however (no priming needed) and will do the same thing again and again....rev it up to get on plane and it just cuts out. Pumping the primer bulb doesn't seem to make a difference, and I've checked all the lines, primer bulb, tank inlet, etc. Replaced a few older fuel lines, rest seem to be in good shape. Replaced fuel filter but that didn't seem to be plugged. Fuel pump was new 2 years ago....only thing I haven't really checked in the fuel system, but it hardly takes maybe half a pump of the primer bulb to firm it back up after it dies, and there's always gas in the clear fuel filter (which is downstream from the fuel pump)'s not emptying as it dies, nor is the primer bulb collapsing. So I did some electrical tests yesterday, on water muffs out of the water, revving up out of the water (but being careful not to go over max rpm), and it's doing the same thing out of the water, only it seems to take somewhat longer for it to die/cut out, and it also slows to a stop a little more slowly when it happens, granted it's not turning a prop against resistance either. I found the two yellow wires to the rectifier had the insulator coating cracked and coming off in places, so I took those off first and tried it with the wires separated to ensure they weren't shorting out on something. No change. Then started measuring voltage coming from the stator. Now I didn't have a DVA multimeter, was just using my Fluke 117, but from what I found you can convert RMS voltage to DVA by multiplying by the square root of 2. Blue to Blue/white wire gave ~230 V at mid rpm (not quite enough to die)=325 DVA Red to Red/white wire gave ~77V at mid rpm=109 DVA At high rpm (enough to cause it to cut out eventually): Blues: 244V=345 DVA Reds: 190V = 268.7 DVA I believe just before I could audibly notice the RPM changing, the volts on both started dropping, and then both drop rapidly as it dies, though I'm sure part of this is just due to the rpm slowing to a stop. Then I also tested the stator resistance with the wires disconnected, engine off obviously (after about 2 hours to allow the engine to cool). Not sure what to make of these numbers: Blue to Blue/white: 1.319 M ohms (that's what the multimeter was showing, so 1,319,000 Ohms!! Red to Red/white: 105.7 ohms Do these tests indicate a bad stator?? Why is my blue to blue/white resistance so high compared to the OEM chart values (Black stator with glued in flywheel magnets as far as I can tell. Flywheel and it's magnets are painted red however.) Or is something else like the switchbox or coil packs the issue/I need to do more testing?? Or do you think that it still is somehow fuel related??? Any help would be greatly appreciated! Thank you in advance!!

Outboard Spares Response
Good Day, Wow! you've gone to quite a bit of effort on this one. To me it sounds like it could be a couple of things but most likely the stator. I'd suggest it's probably got a bad coil and is failing at high RPM. The only other thing it could be is a vacuum issue on the fuel delivery at higher RPM/ Load. Something as simple as a blocked breather could be causing this. One other your control box alarm/horn system working? When you turn on the ignition you should get a "beep" from the control box. The reason I ask is that from memory these engines have an oil warning module that will let you know if your oil level is low or empty. If that is faulty then it may be the cause of your issues. It should sound an intermittent beep from the control box horn (again from memory) if it low on oil, but if your horn/alarm isn't working then you'd never know. The oil module is the small square box with about 5 wires coming from it. They were blue or black in color and about roughly half the size of a cigarette packet. These are the couple of things I'd be looking at, but unfortunately ignition issues can be tricky things to solve. Hope this helps. Cheers

Yamaha 90etlj no fire

By: on 28 November 2018
I have a Yamaha 90etlj that I can’t get to run. It will turn over no problem, but am getting no fire to the plugs. I removed the kill wire on the cdi and it fired right off. When I put it back on it of course killed the engine. Then the next time I tried cranking, it fired right off. Took boat to boat ramp again, and nothing. What is going on? Is it possibly a bad key switch, or does it sound like I have a short somewhere. Thanks.

Outboard Spares Response
Thanks for your question. It certainly sounds like a faulty ignition switch, or kill switch. I'd be checking the wiring of both to ensure there is no corrosion or short to ground somewhere in the loom. I hope this helps. Cheers

Battery good, flywheel won't turn.

By: on 27 November 2018
When I went to wide open throttle, the boat didn't plain. The motor vibrated and a knocking noise from lower unit area. Eventually motor over heated and shut down. It started again but went only a short distant before shutting down. Now when cranking, the flywheel doesn't turn. Yamaha 70 hp outboard-1993

Outboard Spares Response
Thanks for your question. It sounds like your engine has now seized either to an overheating problem, but I'd say more likely to an internal power-head failure. If the boat wasn't planing at wide open throttle and there was a knocking noise, but the alarm wasn't coming on then something is seriously amiss. I'd be pulling the cylinder head off and inspecting the bores. I hope for your sake I'm wrong as your engine could need a rebuild. Cheers

Help please

By: on 1 November 2018
We have a 6hp mercury 2 stroke engine with no spark to either cylinder we changed the spark plugs as they had seen better days but still the same. Someone diagnosed it as a faulty cdi box but after changing that this evening it's still the same. Any help or info would be greatly appreciated. Or if anyone can fix it we are west Yorkshire UK

Outboard Spares Response
Thanks for getting in touch! I'd be looking at the stop switch. If you have no spark on any cylinder and you've replaced the CDI the next easiest thing to check is that the stop switch isn't faulty. It quite easy to trace the wire from the stop switch to the ignition pack and disconnect it. If the spark then returns, replace the stop switch. The other issue could be a faulty stator or triggering coil under the flywheel but it does depend on which model of Mercury 6hp you have. I hope this helps. Cheers

No spark on 1978 Mercury 200 20hp

By: on 24 October 2018
I purchased a 78' Mercury 200 20hp with electric start. It hadn't been ran in 2 years the guy said. So I worked on it and got it running with the first key turn. It also has controls and steering. So, when I got it to start running good I made a console for wheel and place to connect the controls. The key switch was not located in the controls so I took original one out (the electrical wires were snipped just outside the control box) and put the aftermarket one in the controls. There are four wires coming from the key switch, of which two go to the battery and two go to the engine. After all this was bolted down and set, I started the engine and it ran for about 3 minutes and then died. I figured it was a fuel issue so I went to pump the bubble. Cranked it and noting happened and I could tell it wasn't even wanting to start. Checked for spark and there was none on either cylinder. So researched online and figured it was the switchbox. I purchased a supposedly good used one from eBay and replaced the one on my engine. Turned the key and it started right up. Ran for about 3 minutes and then started sounding funny and I happen to notice my water hose fell off the lower unit so I turned the key switch off. Hooked hose back up and tried to start the engine. Nothing. Hoping it might be a fuel issue I pumped the bubble and cranked it over again and could tell it was a spark issue again. Checked for spark and no spark again. I have no idea and this is my first outboard so I know nothing about them. I appreciate the help!

Outboard Spares Response
OK, so you could try disconnecting the stop wire (black with yellow trace) to the switch box. If the spark returns then it's likely you have a stop circuit fault. Obviously be careful doing this as if the engine starts running you won't be able to turn it off easily. Use a spark tester for safety sake. If this doesn't resolve the issue, then check the trigger under the flywheel for shorts in the wiring to ground. A faulty trigger can cause switch-box failure. I'd be betting on the stop circuit fault. Cheers

89 evenrude 150 hp 2 stroke

By: on 21 October 2018
The engine will run fine ans idle forever. I can hit the water and intermittently it will shut down to just above an idle. The boat will travel but seems like an ignition problem if you throttle any more than a no wake speed. I have checked the primer bulb and it is tight when it happens. If i kill the ignition for a few seconds, it will restart and work fine again. Also since this problem started my warning buzzer comes on at random when starting and/ or while running. The engine has not been charging for a while, and the tack. As well. It is a very special boat and any advice would be helpful

Outboard Spares Response
Thanks for your message. Ok, so the charging issue and tacho issue should be related and would typically point to a faulty rectifier regulator. As for the other concerns. Your engines powerpack has "quick-start" which increases the RPM at idle when your engine is cold. When it gets to temperature the heat sensors in the cylinder head send it a signal and it reduces the RPM to idle speed. Your engine is also fitted with S.L.O.W which stops the engine from Revving over 2500 RPM to protect it from harm. There's a few things to check. Ensure the engine does not have an overheating problem. Disconnect the tan wire from the pack (that goes to the temp sensor) and re-test, if it's now ok the temp sender is possibly faulty. Also check that this tan wire is not rubbing against a spark plug wire as this can cause interference. See how you go with this. Cheers

91 yamaha c40elrp

By: on 20 October 2018
Very rough idle in gear all of a sudden smooths out with rpm increase runs strong at high rpm. Rebuilt carbs changed crank seals, reeds,fuel pump plugs. Now looking at ignition has good spark cranking possible cud or coil problem? I will ohm check what I can just looking for some experience and thoughts.

Outboard Spares Response
Thanks for getting in touch. I'd think fuel rather than ignition for this model (unless it is just an ignition coil) as they're a pretty solid ignition. I'd be double checking the adjustments on the carbs to make sure they're spot on. They can be tricky to tune and this would make sense in what you are saying regarding the rough idle but smoothing out as RPM increases. Also, what oil to fuel ratio are you using? It could be something as simple as running the mix too rich. Also, from memory the C40 were a twin cylinder. These engines, like every two cylinder engine ever made were a bit lumpy at idle so it may just be the engine. I hope this gives you something to work off. Cheers

89 yamaha 115 v4

By: on 18 October 2018
Having a horrible misfire after 1/4 throttle .starts and idles fine . has spark to all cylinders , new plugs . have ruled out that it could be anything in fuel system from tank to motor . compression tested all 4 cylinders all came in abve 130psi . were to go from here ?

Outboard Spares Response
Thanks for your message. There's a couple of things to check. Timing. It still could be a timing issue. Secondly, if not timing. Disconnect the green wires to the regulator and re-test, it could be a faulty regulator. Now, this is where interpretation comes into things. When you say horrible misfire, it could be the engines RPM limiting function coming into operation, not necessarily a misfire. This comes into operation when the engine is running hot, or if the overheat sensor is faulty (try disconnecting the pink wire to the power-pack). Low oil in the top engine oil tank will also cause this. Also check the pink wire is not in contact with a spark plug wire. Hopefully one of these will point you in the right direction. cheers

No spark when warm

By: on 5 October 2018
Help please. I have a johnson v4 140 1985. It runs sweet but after about 15 mins and I go to neutral the motor cuts straight out. It wont restart unless I leave it alone for about 3 to 4 nins then it fires up and again runs fine. I can go in and out of neutral with no problems but after a few minutes when warm again it cuts out again. Any suggestions please. Cheers David

Outboard Spares Response
Hi David, from what you've said it sounds to me like a power pack issue. Power packs that are on their last legs will typically fail when they get warm (due to engine/block getting to temperature). I may be wrong, but that's where I would be looking. Cheers

1981 Johnson 50 hp

By: on 2 October 2018
Runs great for about 1/2 hour then out of nowhere it cuts out. Let it sit 5 10 15 minutes and it will run for a short Time again. I don’t believe it’s fuel and I can’t check spark because I’m always breaking down in a bad spot,

Outboard Spares Response
Thanks for sending in your problem. It's a tough one to diagnose. To me I instantly think that it sounds like a power-pack, but it could also be stator. If it's not ignition, it could be something as simple as the breather on your fuel tank being restricted and the engine running for a period but then starving for fuel. To check if it is a spark issue, you really need to get the engine to fault in a controlled environment and have a spark tester ready. A boat ramp on a quiet day is a good spot if there is no boat traffic. From here you'll be able to safely check if it is an ignition problem or something else altogether. Good Luck. Cheers

1989 Evinrude 70 hp cutting off at high rpm

By: on 25 September 2018
Recently my motor started cutting on and off at higher rpm. Motor has ran fine up to this point, I took it out and it was real sluggish coming up in rpms, when it finally got up to 3000rpm range it started cutting on and off like I was doing it with the switch. I have changed the power pack being the easiest but it had no effect. Sometimes it will cut on and off and sometimes it don't.

Outboard Spares Response
Thanks for getting in touch. The problem could be your trigger. A bad trigger will destroy power-packs, so even though you've put a new power-pack on, if the old trigger is shorting to ground then it will have ruined the new pack you've just fitted. Ok, so a couple of other things you could try. 1) Disconnect the yellow wires from the stator to the rectifier and re-test. If the miss goes away then you've got a faulty rectifier. 2) If the engine does not have a miss below 2500 RPM then it could be a faulty temperature probe in the cylinder head (assuming your model has the S.L.O.W feature). Disconnect the Tan wire from the temperature switch and re-test. If the miss goes away then your temp switch in the head is faulty....HOWEVER, check that your engine does not have an over-heating issue and that your control box alarm/warning horn is working correctly. Normally when the engine overheats the alarm sounds and the S.L.O.W function kicks in and reduces the engine to 2500 RPM. Anything over 2500 RPM and the engine carries on a bit. 3) If none of the above work replace spark plugs and check coil leads for shorts to ground. 4) The problem could be a bad stator. Higher RPM problems generally indicate bad stator. There are a bunch of tests to diagnose this but you'll need a workshop manual, or pay a technician to test it for you. Good Luck! Cheers

Evinrude 70 1995

By: on 15 September 2018
Hi there, I have an evinrude 70HP with a tiny spark on the bottom cylinder. Not enough to fire but there is something going through. I've tested the stop circuit, blocking diode, changed the leads, checked the plugs put in new timer base, stator, power pack, coils. It's possible that I blew something in the new power pack because I replaced it before putting in a new timer base, but the resistance is what it should be on all the wires so maybe not? Only components left are the rectifier, wiring loom and ignition switch. Could it be any of these??? Thanks

Outboard Spares Response
Thanks for getting in touch. I think you've probably answered your own question. Replacing the powerpack before the timer base is typically not the best option as a bad timer base will destroy powerpacks. I had one trade customer fit 3 new power-packs (bought from a competitor) until I mentioned to him the trigger was probably the underlying issue. This was on the same model as your outboard. I couldn't be 100% certain but unless you've got a weak trigger magnet in the flywheel I'd say your powerpack is the cause. Good luck!

1973 20 hp Mercury 3669833 wont get up on plain

By: on 11 September 2018
It runs great after i went threw the carb but still wont plain out, its on a 15ft 1987 dura craft semi V so it should push it pretty good. But it doesnt. what do i need to check next?

Outboard Spares Response
Thanks for your question. I may be wrong, but I think lack of Horsepower is most likely your problem. I'm not familiar with the boat model you have, however most 15ft boats require about 40hp as a minimum to plane. If it's not a lack of horsepower then it could be an engine height issue. One most boats the cavitation plate should be about level with the bottom of the hull. For example: If your cavitation plate is 4 inches below the bottom of the hull then you'll find the engine will struggle to plane the vessel. Especially a 20hp on a 15ft boat. I hope this helps. Safe boating. Cheers

Electric stsrt

By: on 10 September 2018
I am troubleshooting the.key ignition and found no voltage at the red wire on key switch. Isn't there supposed to be 12volts. At key switch? Jumped solenoid works fine.

Outboard Spares Response
Good Day. Yes you should have voltage at the ignition switch. If there is no voltage to run through the switch to open the solenoid then the starter won't crank over. Good Luck! Cheers

weak spark

By: on 31 August 2018
Hi I have a 60hp tohatsu with weak spark out of every coil am thinking the cdi?

Outboard Spares Response
Howdy! Weak spark is often caused by a failing stator (exciter coil) rather than a faulty CDI Unit. The stator is where the spark is generated so to me this would be the first thing to test. Using a digital multimeter with DVA adaptor I'd be testing the output. You may need to jump online and find a manual for your engine which will give you the readings, etc. I hope this helps. Cheers

92 Mariner 115 2 stroke

By: on 30 August 2018
Ran good the last time until the end it would be running a good fast speed then it boged twice then picked back up and was fine...the next time it ran good for about 20mins then boged and quit. Several times and then dead it home changed the plugs ran good for a minute then boged bottom 2 plug looked blackish changed the wires and bottom 2 coil packs same thing it seems like soon as it heats up some starts skipping looks to be the bottom 2 plugs...has new fuel filter and water separatrater even took a new gas tank and hooked it up... should I replace the switch box

Outboard Spares Response
Good Day, Thanks for getting in touch. Unfortunately it could be 1 of 3 things if it is the bottom two cylinders that are providing only intermittent spark. The switchbox, the stator or the trigger. All supply either cylinders 1 and 2 OR cylinders 3 and 4. If you can get your hands on a Digital Multimeter with DVA adapter that would be a good start. There's a whole bunch of tests you'll need to perform in order to test properly and you'll want to try and get your hands on the CDI Electronics Troubleshooting guide. This guide has all the specifications and information you'll need to test properly. Good Luck!

Old Ducati 5,5 hp

By: on 30 August 2018
Hey! Got an old 70s?? boat engine and i can't get a spark. I've replaced the spark plug cap and the spark plug. Still nothing. What else can it be and how to i check it? Gotten tips about the coil and flywheel but i have no clue how to check it. I only have an high end multimeter to check with.

Outboard Spares Response
Good Day, Thanks for getting in touch. If the engine is CDI ignition then I'd be checking the output from the CDI Unit to the coil and the stator coil to the CDI Unit. Most high end multimeters will have the proficiency for a DVA Adapter. You'll need the DVA Adapter to check voltage. I didn't realise Ducati ever made an outboard so unfortunately I'm not familiar with their ignition type and can therefore not give you much more advice than I have. Good Luck with the diagnosis. Cheers

z200txrz yamana 200 2001year

By: on 22 August 2018
engine will only run if I keep keyswitch on start position with start engaged when let go of keyswitch engine will eventually stop running

Outboard Spares Response
G'day Dan, Thanks for getting in touch. From what you are saying it sounds like you may have a faulty ignition switch. I'd be looking to replace this first, or if you have a mate with a complete control box assy, plug that straight into the harness on your engine bypassing the existing ignition switch, etc. If this fixes the problem I'd say it would be the ignition switch. Cheers

1981 70hp Mercury 2 stroke no start

By: on 20 August 2018
I’m only getting a very faint spark on the top cylinder and nothing on the bottom 2. Previous to this we’ve been out every couple days and she’s run awesome. I believe it to be coincidence But I will break down what happened leading to this: Running the boat everything good Load up parked at home Next day dropped the lower unit and changed impeller Reinstalled changed leg oil (both done as maintenance) Next day try to start her up and find the current no start issue occurring.

Outboard Spares Response
Howdy! Thanks for getting in touch on this problem. I'd suggest it is one of 2 things and totally unrelated to you dropping the lower unit. Weak spark on one cylinder will be a faulty ignition coil or faulty switchbox. If you have a digital multimeter with a DVA adapter the i'd be measuring voltage coming out of the switch-box to the coil (green primary wires). You want to check this with the wires connected to the coils, at both the switchbox terminal end and at the coil terminal end. You should have a reading at both ends of at least 150V. Another more simple test is to switch over the primary wires from the switch-box on the coils. If the weak-spark shifts to another coil you'll know it's most likely a switch box problem, not a coil issue. Remember, you'll want to have all coil (spark plug) leads disconnected from the spark plugs and connected to a spark tester to make sure there is no damage to the engine or yourself. I hope this helps! Cheers

No spark on port side

By: on 19 August 2018
Hi i have a gt150 johnson 1985 has no spark on port side at all i replaced stator rectafire power pack new timmer base new plugs new wires new battery new switch still no spark i dont know what kind of fluck tester to get 112 113 115 116 117 i have a dva 640 but dont know what tester to buy some one help me please thank you

Outboard Spares Response
Good Day and thanks for your message! A multimeter with a DVA adaptor will allow you to test just about everything on that ignition. As for your ignition problem. I would be checking the stop circuit as this may be your issue. Remove the stop wires from the power-packs (ensure your spark plug leads are connected to a spark tester) and re-test. If spark comes back on both banks then switch the powerpacks over and reconnect the stop wires. If the problem stays on the same bank then I'd think you've got a problem somewhere in the stop circuit. I hope this helps, Cheers

Loosing spark mariner 50hp 1995

By: on 5 August 2018
Hi outboard spares I have a problem on the top cylinder. When it runs in idle all 3 cylinders are firing, but as soon as i touch the throttle the spark on top cylinder disappers. Also a continues alarm is on I have tryed to switch the coils around, checked all wires, checked oil level sensor, boiled the temp sensor. Nothing is helping. I have tryed almost everthing i think

Outboard Spares Response
Good Day, Thanks for getting in touch. There are a few other things it could be. 1) The alarm. These engines have a small square oil module. Often when they have failed or are faulty they will send the alarm off. This could be the reason your alarm is going off, assuming it is going off almost immediately. Additionally I think the module may also limit RPM to avoid engine failure due to lack of oil, but I cannot be 100% certain. This could also explain the spark on number 1 dropping out. 2) Faulty switchbox or trigger (timer base). The other problem you may have is a faulty switchbox or trigger. If switching the coils has made no difference, then either of these 2 parts could be the culprit. You'd need to test the trigger DVA output connected and also disconnected from the switchbox. This will tell you whether the switchbox is receiving sufficient output from the trigger. I'd also be inspecting the trigger wires for any "shorts to ground". If you don't have the tools to do this then perhaps take it to a qualified Marine Technician who has the equipment to do so. Give these a try and see how you go! Cheers

1989 Mariner 90 HP 3 cylinder outboard - Top Cylin

By: on 21 July 2018
Hi, hoping you might be able to put me in the right direction. The top cylinder has spark, fuel, and compression. However it appears it is not firing. While the motor is running, if I remove the spark plug boot from cylinder 1, nothing changes. Do the same thing with cylinders 2 and 3 make a noticeable difference in the way the engine runs. The engine will stay running if only cylinder 2 or cylinder 3 has the spark plug boot on, but if only cylinder 1 is plugged in the engine dies. Not sure where to go from here. Thank you.

Outboard Spares Response
Good Day, Thanks for getting in touch. Firstly, is there an issue while the engine is running? Meaning, if you use the engine in a normal operating way does it lack power? I'm just trying to establish what lead you to trying to diagnose an ignition problem, because if the engine has fuel, spark and compression then realistically it should be running fine. If not, timing is then possibly a problem or weak spark on the top cylinder. These engines run a Coil on each cylinder . You could try swapping these around (move the top Coil to the middle and the middle Coil to the top) and see if the problem shifts to the middle cylinder. If it does shift then it's most likely a coil that is no longer performing within specification and then all you'll need to do is replace it. It's worth also checking your trigger wires going to the top coil. If you have any wires that are shorting to ground, then they'll cause a coil to play up. I hope this has been of some assistance and I apologise for the delayed response. Cheers

1989 Suzuki DT140 Outboard 2 stroke - Sputtering

By: on 19 July 2018
Motor runs fine upon starting but when giving it gas it sputters as if it is missing. Have had plug changed and carburetor checked and all seems good. The tech says it appears to be the ignition system and that this motor uses pulsars but its difficult to diagnosis. Any suggestions for how to diagnosis or repair.

Outboard Spares Response
Hmmm sounds like a curly one! I'd be getting the mechanic to check the stator output with a Direct Voltage Meter. This will allow you to see if the stator is putting out sufficient voltage. Also, a simple spark test (using a spark tester) could help in possibly identifying which cylinders are breaking down. I must admit, I'm not too familiar on Suzuki ignition systems, but it does sound like an ignition issue. If you can get your hands on a manual then that will be your best bet to resolving the problem and being able to test each component properly. Sorry I can't be of better help on this occasion.

1986 60hp mariner

By: on 15 July 2018
Hi my motor will crank over first go but if it doesn’t start first go the battery won’t crank it again , it’s a brand new battery and all the wires have been replaced if iv had it running for 10mins and turn it off same thing but if I pull start it it will start first go , iv had it in the shop about 7 times now and still same problem any advice I’d greatly appreciate

Outboard Spares Response
Hey, thanks for getting in touch. Have you had the technician strip the starter motor and check that all contacts are clean and the brushes are not worn? It's a pretty old engine and if the starter is of the same era (meaning it hasn't been replaced) then you possible have a starter motor in need of some repairs. These engines have a lot of compression and you really need a healthy starter and battery to ensure you don't have any starting woes. Let us know how you go! Cheers

2002 Mercury 90hp 2 stroke

By: on 30 June 2018
When I start the engine it runs on one cylinder but if I turn the key back about midway to off position it runs fine and I have changed ignition switch and safety switch and stator and coils any ideas

Outboard Spares Response
Good day George, sounds like a tricky one to me. It sounds like an ignition switch problem, but if you've already replaced that then it's obviously something else. I would check inside the control box and make sure nothing is loose and shorting to ground. Also, try running another engine harness (between control box and engine). Sometimes if you get moisture in the main harness it can do funny things. Otherwise, it could be your trigger (next to the stator) or your main engine loom (main loom on the engine itself). I'd be leaning towards the engine harness provided the ignition switch has been installed correctly. I hope this helps. Cheers

1994 mariner engine keep running

By: on 25 March 2018
any suggestion have checked wires

Outboard Spares Response
Could be a timing issue but you'd really have to have a mechanic check the issue for you.


By: on 1 March 2018
I didn't realize that battery problems could cause the outboard motor to not ignite. My boat has an outboard motor, and I've been having issues starting it. Maybe I should have the battery checked to see if that's the problem.


By: on 15 January 2018
Very handy tips, thankyou!

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