Merc 40hp 2cyl 2 stroke stalling issue. Help please

[MystyBlue2]

Ok well today my head is banging!!! Grrrr

All earth's checked and all seem fine
When i remove both plugs and leads and earth them to engine body they both blue crisp spark

However when it finally fires up its only running on bottom cylinder i can pull top cylinder lead and no change as can be seen in video a few posts above,

After a little more banging my head and investigation if i disconnect the harness plugs from CDI to coils and swop them over so the bottom harness is now powering the top coil and top harness is powering the bottom coil is seems to be that the bottom cylinder is now dead and top cylinder is now firing!!!

Bearing in mind that both coils spark when earthed to engine body,

Its like the TPM/powerpack/CDI will only allow 1 coil to fire the motor and not both simultaneously!!

Ive traced the wires back from both coils and they lead straight into the power pack module.

If i google my symptoms it could be trigger as in this motor is auto timed by the trigger coil under flywheel so a faulty trigger can throw my timing way off, also the stator coil has a low rpm and a higher rpm coil inside which could be a cause, And the dreaded CDI.

But surely a bad CDI would cause both coils to be dead and no spark at all?

Any ideas on where i could possibly turn to next?

I have no confidence in testing each part with multimeter and dva meter because i have no idea what a dva meter is lol so testing is well out my confort zone and will get a reading and not know what means in the first place lol

Thanks in advance guys hope this makes sense.

 

[Bigplumbs]

I must say you are brilliant for not giving up. You are now I am sorry to say at a point that is beyond my knowledge. All I can think is are you able to buy an after market CDI Unit that is not to expensive to try it. I think you have got to the position where buying the expensive bits on the off chance is not a good idea.

What confuses me and I am sure you is that if you are getting a good spark and if there is petrol it should fire. The way in which you have got both to fire but not at the same time is intriguing.

Are there any outboard places near you that are not too expensive that you could get to have a look at it.....

The other thing I am wondering is what boat you have as would a second hand 50 or 60 hp fit ti as it might be time to look if one might be cheaper now than trying to fix this one.

If you got a 50 or I think 600 in the same model you might find that some of the parts on the 40 will fit it.

 

[Bigplumbs]

I just looked on ebay etc for 50hp or so outboards and The seem to be like Rocking Horse Shit........ So perhaps ignor the bit about lookin for another one in my post above

 

[MystyBlue2]

I must say you are brilliant for not giving up. You are now I am sorry to say at a point that is beyond my knowledge. All I can think is are you able to buy an after market CDI Unit that is not to expensive to try it. I think you have got to the position where buying the expensive bits on the off chance is not a good idea.

What confuses me and I am sure you is that if you are getting a good spark and if there is petrol it should fire. The way in which you have got both to fire but not at the same time is intriguing.

Are there any outboard places near you that are not too expensive that you could get to have a look at it.....

The other thing I am wondering is what boat you have as would a second hand 50 or 60 hp fit ti as it might be time to look if one might be cheaper now than trying to fix this one.

If you got a 50 or I think 600 in the same model you might find that some of the parts on the 40 will fit it.

Yeah the motor is very good and strong and just what i need. Thats why im not giving up as motors at the moment are so hard to get, dunno if its the pandemic or not but good quality motors and really hard to come by or they are 400+miles from me. This motor is 73kg and 40hp, My boat is 12ft cjr hull but very heavy which i why i need a little more power and this 40hp merc has the best power to weight ratio than any other motor ive came across thats why im not giving up as another 40 will weigh too much for my transom to handle.

Obviously if its going to cost upwards of 500 or so to fix plus the 800 he wants when fixed then it maybe time to call it a day and look for something else but the rest of motor is super strong so i would be kicking myself if i end up with a shite engine if i give this one up.

Although £1300 for a super strong engine with a brand new rebuilt ignition system dont seem bad either compared to whats on marketplace at the moment for that price range.

Im looking at this like i wouldnt get rid of a car if it had a blown head gasket and throw a good car away for the sake of £250 on parts and labour

Local boat mechanic charges £60 per hour to "look" if it takes him 4hrs to find it theres £240 straight out the pocket before parts and labour.

I feel like im banging me head off the wall at the moment and maybe the stubbornness of my personality is feeding my headache instead of giving up lol.

The good thing is its still an older 1994 2 stroke so as far is electrical ignition components go it is very limited and basic.

Think i will scour fleebay and but cheap second hand parts within reason until its sorted.

Thank you very much Bigplums for all you help and time. I will keep you posted of my progression!

 

[Bigplumbs]

No problem I am also like you and dont give up.... Mind you it drives my wife mad and it can certainly make me grumpy. and keeps me from sleeping as I keep going over things in my head.....]

Having looked to see if I could find a decent motor to send you a link to I came up with nowt so I actually now think it is deffo worth perseverance on the one you have.

Mind you on Friday my Old Discovery 2 (I have a 2 and a 3) failed the MOT on welding at 11.30 am(too much sea water up its chuff over time)... I got so irritated that by 11 am on Saturday I had bought another one........ I could not face trying to fix the old one (welding not my forte I am afraid)..... No doubt in time this will also fail due to more sea water up the rear end

 

[MystyBlue2]

A screen shot from my owners manual about how the trigger works is keeping me optimistic about the trigger fixing the issue.

Like i mentioned above both coils are sparking but only one cylinder at a time will fire the motor. Like it says in the text attached, the trigger has 2 coils one for each cylinder so im keeping my fingers crossed that one of them coils in the trigger is bad causing my issues. Trigger is ordered i will keep you posted!

 

[MystyBlue2]

No problem I am also like you and dont give up.... Mind you it drives my wife mad and it can certainly make me grumpy. and keeps me from sleeping as I keep going over things in my head.....]

Having looked to see if I could find a decent motor I came up with nowt so I actually think it is worth perseverance on the one you have.

Mind you on Friday my Old Discovery 2 (I have a 2 and a 3) failed the MOT on welding at 11.30 am(too much sea water up its chuff over time)... I got so irritated that by 11 am on Saturday I had bought another one........ I could not face trying to fix the old one (welding not my forte I am afraid)

Lol takes me back 2 years ago when i had a shorty pajero, im a welder by trade so wasnt too bad as all welding was done in work after hours, yeah its sort of a personal decision of how much shit you can put up with before you set fire to it lol

Also how much patience the wife has plays a big part too lol luckily my missus catches more and bigger fish than me so she perseveres with me so i can take her back out to show me up again lol

 

[Rappey]

A spark plug can show a good spark when held against engine but the engine won't start until a new plug is used. Could this apply to a coil?
Is the ht lead properly in the ht cap and coil ?

 

[MystyBlue2]

A spark plug can show a good spark when held against engine but the engine won't start until a new plug is used. Could this apply to a coil?
Is the ht lead properly in the ht cap and coil ?

Yeah ive double and tripple checked the plug, boots and connectors and earths and tried different plugs aswell, same issue...spark against the engine body but only one plug will fire at a time when engine is running leading to running on bottom cylinder only, top plug is wet with fuel but just wont fire for some strange reason...im done in lol,

Dont think it can be a faulty top coil as they both spark..maybe wrong

They are brand new and properly gapped plugs and also tried others too incase of a faulty plug,

If i plug bottom coil power harness from cdi into top coil wires then the problem changes to bottom cylinder dead and top fires...

I honestly dont know why it just wont fire up on both cylinders, theres fuel, compressions are 120 on both and theres spark!!! I hate engines!!! ?

 

[MystyBlue2]

Been thinking seen as i have spark on both plugs but only bottom cylinder is firing and top is wet but clean, what about the possibility of maybe too much fuel wetting top plug and flooding it preventing it from firing?

Ive used a full 5 litre jerry can of fuel just trying to get it to start over the past couple of days and that seems a little too much fuel consumption....unless this is the big eye opener of how thirsty it will be once she is runnjng again lol

Could this be a possibility that maybe something inside carb is not closing properly allowing cylinders to flood and not fire?

 

[Bigplumbs]

That

A screen shot from my owners manual about how the trigger works is keeping me optimistic about the trigger fixing the issue.

Like i mentioned above both coils are sparking but only one cylinder at a time will fire the motor. Like it says in the text attached, the trigger has 2 coils one for each cylinder so im keeping my fingers crossed that one of them coils in the trigger is bad causing my issues. Trigger is ordered i will keep you posted!

That looks very hopeful

 

[Bigplumbs]

Been thinking seen as i have spark on both plugs but only bottom cylinder is firing and top is wet but clean, what about the possibility of maybe too much fuel wetting top plug and flooding it preventing it from firing?

Ive used a full 5 litre jerry can of fuel just trying to get it to start over the past couple of days and that seems a little too much fuel consumption....unless this is the big eye opener of how thirsty it will be once she is runnjng again lol

Could this be a possibility that maybe something inside carb is not closing properly allowing cylinders to flood and not fire?

I think you are on to something with the trigger. I would 'rest' a while until that turns up and try it rather than mess with the carb any more.

You have done far more than many people would and I think you are narrowing it down to the issue. I have also learnt quite a bit.

 

[MystyBlue2]

I think you are on to something with the trigger. I would 'rest' a while until that turns up and try it rather than mess with the carb any more.

You have done far more than many people would and I think you are narrowing it down to the issue. I have also learnt quite a bit.

Yeah suppose your right, so many scenarios have been running through my head over night im absolutely knackered lol, il try trigger then move on until its sorted, il keep you posted cheers mate ?

 

[MystyBlue2]

That

That looks very hopeful

Hi well today had been a fabulous day!

Yesturday i ordered a mercury flywheel puller from amazon prime, got delivered this morning my new/second hand trigger came today so i set away removing flywheel and stator to get at the trigger...fitted new trigger and put everything back together and torqued up flywheel to spec,...

Hey ho presto! Started first time on key and purrs like a kitten on both cylinders, runs lovely at idle and higher rpms with no stalling, Pulled both plug leads and engine hesitates with each individual plug lead removed, im so exited and happy! Now time for a service and winterized and put to bed ready for 2021 summer season.

Like i suspected one of the smaller trigger pulser coils must have been faulty inside trigger assembly causing both plugs to fire but knocking the timing way off so bottom cylinder was firing at TDC and top cylinder seemed to be firing off TDC causing that top cylinder missfire. New trigger seem to put the timing right again and shes running super strong,

Thank you for all your help and advice, hope this helps someone in the future. Big thanks to Bigplumbs and everybody who commented on this thread!

 

[Rappey]

Glad to hear you've fixed it and hopefully not at great cost plus I'm sure some of us have learnt from your endeavours ?

 

[Bigplumbs]

Yeeaahhhhhhhhhhhhhhh..... Brilliant result....... Your tenacity worked very well and now you have a good engine that many others would have thrown away.

At least post a video of her puring away

 

[MystyBlue2]

I will take a vid and post link tomorrow, im so chuffed to bits folks, the trigger cost £55 second hand and a bit of determination perseverance and help form you guys shes purring away like new. Total cost £855, need to buy a killswitch though as its missing from remote box! Thanks again guys ?

 

[alt]

Well done. Any pics??

Link to the trigger? I have the same engine on my tender, so its great to have this info.

 

[MystyBlue2]

The trigger assembly on this outboard is a fixed position one, no throttle timing advance as this is what i was suspecting the issue to be at the beginning but once i dug deep in my manual the trigger sits fixed on a roll pin and doesn't have a spark advance linkage. I will post plenty of pics and a vid of it running

 

[MystyBlue2]

Alright folks see pics attached and video link of her running!

Purring away like a 2 stroke should. Im chuffed to bits and spring 2021 cant come quick enough now lol.