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

[MystyBlue2]

Ok well today i have removed carb and all the tiny screws and cleaned out all the tiny orifices with copper wire and sprayed carb cleaner into each and every single hole then blasted with compressed air. It looked pretty clean anyways when i took it apart but i spent 4hrs making sure everything was super cleaned and blasted. Also before i removed carb i sprayed some carb cleaner into carb throat when engine was running and no increase in RPM at all. Did not make any difference to revs or engine pitch, Still died.

Ive downloaded a manual and set all screws to factory spec.

NEW ISSUE!!

now wont even fire up!!

Primer bulb is firm and stays firm, new fuel and plugs cleaned all earths i could see under the cowl and NOTHING!!

i double checked carb specs with manual incase i did it wrong and still the same thing.

Redone a compression check with different gauge and getting 120psi on both cylinders so i removed the plugs and earthed them to the block.

Top cylinder is like a lightning bolt and bottom cylinder is dead! No spark at all. I switched the plugs over incase of a faulty plug and same thing. Bottom cylinder no spark

Would a bad bottom ignition coil cause my previous problem and now a completely non running engine?

I would expect it to atleast fire up and run like a bag of spanners just on one cylinder.

Any help here will be greatly appreciated thanks

 

[Bigplumbs]

I would expect it to at least fire the good cylinder which has the spark. It sounds to me like you have 2 issues now.

1) Something wrong with the ignition to the one cylinder.

2) No fuel actually getting into the cylinder at all hence no firing.

I see you swapped plugs but is it possible to swap any other parts on the ignition system to see if you can narrow the issue of the non spark on the one side.

Also I would make the fuel a little richer than spec to see if you can get it to fire....... Also was the gasket ok on the carb bowl because if air can get in here it will give issues. Also is the choke working ok

You could also crank it over while spraying in some carb cleaner as this might get it to fire which would demonstrate that fuel is not getting through.

If you take the plugs out after turning it over are they wet.

Also have you checked that the kill switch is on as this will stop any fireing. But you got a spark which should not happen if the kill switch is off

 

[MystyBlue2]

I would expect it to at least fire the good cylinder which has the spark. It sounds to me like you have 2 issues now.

1) Something wrong with the ignition to the one cylinder.

2) No fuel actually getting into the cylinder at all hence no firing.

I see you swapped plugs but is it possible to swap any other parts on the ignition system to see if you can narrow the issue of the non spark on the one side.

Also I would make the fuel a little richer than spec to see if you can get it to fire....... Also was the gasket ok on the carb bowl because if air can get in here it will give issues. Also is the choke working ok

You could also crank it over while spraying in some carb cleaner as this might get it to fire which would demonstrate that fuel is not getting through.

If you take the plugs out after turning it over are they wet.

Also have you checked that the kill switch is on as this will stop any fireing. But you got a spark which should not happen if the kill switch is off

I will give a go of spraying carb cleaner into carb throat to see if it fires, i will also try and make mixture screw a little richer aswell,

I was wondering if a faulty coil or trigger would cause the intermittent/no spark issue. I did re-use all gaskets for the carb as they all seemed in really good shape, the killswitch was fully in and remote box was in neutral

Do you think i should replace all carb gaskets?

Thing is i dont want to be piling loads of money i aint got into the engine as the seller said if i cant get it running i can just take it back to him. But i think its something small/ annoying as the main parts of motor seems really strong and in good shape. When i press the key in i can hear a "click" from the enricher valve so im assuming the choke this is working correctly.

I could be wrong but from what im reading online culprits could be...

Trigger
Faulty CDM ignition coil
Fuel related issues but what??

Whats your thoughts and what would you think is the most likely culprit of my symptoms?

Thank you for you help!

 

[MystyBlue2]

I would expect it to at least fire the good cylinder which has the spark. It sounds to me like you have 2 issues now.

1) Something wrong with the ignition to the one cylinder.

2) No fuel actually getting into the cylinder at all hence no firing.

I see you swapped plugs but is it possible to swap any other parts on the ignition system to see if you can narrow the issue of the non spark on the one side.

Also I would make the fuel a little richer than spec to see if you can get it to fire....... Also was the gasket ok on the carb bowl because if air can get in here it will give issues. Also is the choke working ok

You could also crank it over while spraying in some carb cleaner as this might get it to fire which would demonstrate that fuel is not getting through.

If you take the plugs out after turning it over are they wet.

Also have you checked that the kill switch is on as this will stop any fireing. But you got a spark which should not happen if the kill switch is off

Also the top plug was wet with fuel and the bottom plug was covered in black dry soot. They are brand new plugs aswell. Thats why i removed plugs and earthed them to block to find bottom cylinder was not firing at all whick explains the soot, i may stand corrected on that one though....

 

[Bigplumbs]

Normally if a cylinder is not firing the spark plug will just be wet.....Soot is an indication that it is firing but running rich or with too much oil.

A faulty ignition coil can certainly be the cause of these issues. Can you swap it across to the good spark to see it it fires that one.

If the gaskets looked ok that is most likely not the cause but just be aware that sometimes if they look good they can still be letting air in.

Post some pics of this engine here so we can get a better idea of the general state of it

 

[Bigplumbs]

Regarding the Triger and Stator (Alternator) if one side is sparking well then these 2 bits are likely to be OK. The Coil however could be bad. Also look at the HT leads from the coils to the plugs and make sure they are ok especially the ends are not corroded when the connect. Plug caps also can be an issue

 

[MystyBlue2]

Normally if a cylinder is not firing the spark plug will just be wet.....Soot is an indication that it is firing but running rich or with too much oil.

A faulty ignition coil can certainly be the cause of these issues. Can you swap it across to the good spark to see it it fires that one.

If the gaskets looked ok that is most likely not the cause but just be aware that sometimes if they look good they can still be letting air in.

Post some pics of this engine here so we can get a better idea of the general state of it

Yeah i will get some pics posted today and il try and switch coils over to see if the issue follows the coil.

Thank you for your help mate ?

 

[Bigplumbs]

Trying my best. I am no expert but I just have many engines of all sorts and generally try to have a go my self at fixing things like you do

 

[MystyBlue2]

I have taken 3 videos and pics of it running and then playing up,I will post pics and link to vids first thing in the moring,

And thanks again Bigplums you've been a massive help ?

 

[MystyBlue2]

ok well today I have ripped off the reeds to inspect as i have been informed that reeds can cause similar issues, turns out all the petals are in great shape and sealing correctly, when I turned and look at the sky I could not see any daylight through them so I'm assuming they are all ok see pic.

this is why I'm sort of leaning toward an electrical/ignition problem as fuel pump is working correctly as primer bulb is constantly staying firm and plugs are wet and will run and not bog down at higher RPM, the seller and I have both removed the carb and stripped and rebuilt with carb cleaner and small wire through every orifice I could find, reeds checked out ok, compression is 120 both cylinders...im totally stumped.

the motor seems to start right up with a bit of throttle from cold and progressively misbehaves the longer/warmer it gets until it is impossible to get it fired up again.

bottom cylinder is firing as bottom plug seems to be burned but top cylinder is as clean as it was from the box apart from being slightly wet with fuel.

stator?
trigger?
Ignition coils?
CDI?

any ideas on what ignition components could cause these issues. see pics and link to vids.

thank you in advance

 

[Bigplumbs]

I have another idea which I learned about on a smaller 15 hp merc with a similar issue.

On that motor the kill switch wire located on the engine had become frayed over the years from the vibration as it was rubbing on the cowl/metal of the engine and it was earthing out the ignition as the engine vibrated. Yours sounds sort of similar. When the guy spotted this you could clearly see where the wire had rubbed through. I am wondering if when you did the carb work you might have had a similar issue with a wire and it was pressed nearer to the source of earthing.

I would check all the smaller wires in this regard and see if any of them are frayed in such a way.

I agree with you that this is not a fuel issue it is somthing on the ignition.

I am sure this is getting very frustrating for you but if you keep at it I am sure you will get there in the end

 

[MystyBlue2]

Yeah there is alot of wires so its definitely possible that one has been damaged, i will start investigating tomorrow and hopefully find the culprit, i just hope its not a powerpack/CDI unit as its a whopping £450!

Thanks for your help i will post as soon as i have any news! Cheers ?

 

[Bigplumbs]

Yeah there is alot of wires so its definitely possible that one has been damaged, i will start investigating tomorrow and hopefully find the culprit, i just hope its not a powerpack/CDI unit as its a whopping £450!

Thanks for your help i will post as soon as i have any news! Cheers ?

When it come to outboard electrical and electronic item make sure you search ebay as offten you can find them at a fraction of the price..... I needed a new Rectifier for my 200hp Yam outboard. The OEM Price was £399 plus VAT on ebay I found new ones for £27.50 delivered.......... I bought 2

 

[Bigplumbs]

Looking at your pics that engine looks quite good under the hood.......... I have another rather off the wall idea. Looking at the spark plug leads and their lengths I was wondering if they might be connected to the incorrect plugs. The long one going over the top made me thing this.... Just a possible stupid idea but just a thought

Just looked on line and found this pic. on looking at it yours does look correct just rotated differently

 

[MystyBlue2]

Looking at your pics that engine looks quite hood under the hood.......... I have another rather off the wall idea. Looking at the spark plug leads and their lengths I was wondering if they might be connected to the incorrect plugs. The long one going over the top made me thing this.... Just a possible stupid idea but just a thought

Just looked on line and found this pic. on looking at it yours does look correct just rotated differently

Ive swapped the main wire harnesses around that power each coil, no differance ive also put top plug lead on bottom plug and no differance.

I notice on you pic that it looks to me that motor has a new/different CDI pack to mine, hope this isn't a commom fault...

 

[Rappey]

I'm pretty sure I've had carb cleaner that does not combust/ignite so spraying it in or around a running engine may not show anything but I think you've moved on from there.
A coil pack failing as it heats up?
Swop them over and see if the non firing cylinder changes.

 

[MystyBlue2]

When it come to outboard electrical and electronic item make sure you search ebay as offten you can find them at a fraction of the price..... I needed a new Rectifier for my 200hp Yam outboard. The OEM Price was £399 plus VAT on ebay I found new ones for £27.50 delivered.......... I bought 2

Speaking of rectifiers...mine seems to get warm when engine is running, is this normal or could this be an indication of it failing or something else failing?

Im going to spend the full day today ripping out all the earths and cleaning them all up, not looking forward to it as its like spaghetti junction around the CDI and scared of breaking or pulling a wrong wire lol thanks for all your help and ideas ?

 

[MystyBlue2]

I'm pretty sure I've had carb cleaner that does not combust/ignite so spraying it in or around a running engine may not ship anything but I think you've moved on from there.
A coil pack failing as it heats up?
Swop them over and see if the non firing cylinder changes.

I have put the bottom coil (the one that is firing) on top plug and it fires up. And the top coil that is on bottom plug is still dead.

However i earthed the plugs to ground and top plug was like a lightning bolt but would not fire and combust fuel and bottom plug was super weak but thay was the only cylinder that fires up the motor.
However now there's no spark at all on top coil!!! This is completely doing my head in lol

I think its either both coils are knackered and needing replaced or maybe a classic failing stator/trigger/CDI symptoms.

Ive been watching YouTube videos on the above failing components and they seem very similar.

 

[Bigplumbs]

Speaking of rectifiers...mine seems to get warm when engine is running, is this normal or could this be an indication of it failing or something else failing?

Im going to spend the full day today ripping out all the earths and cleaning them all up, not looking forward to it as its like spaghetti junction around the CDI and scared of breaking or pulling a wrong wire lol thanks for all your help and ideas ?

Rectifiers always get hot many have large heat sinks to deal with this......... Getting hot/warm is normal

 

[MystyBlue2]

Rectifiers always get hot many have large heat sinks to deal with this......... Getting hot/warm is normal

Cheers for clearing that up, one less thing to worry about lol