yamaha 40 firing issue

[camtheribman]

Hi there, again my engine is playing up and not running on all 3 cylinders. I have tried bleeding the carbirattors to make sure there is no gunk in them, they were fine. The spark plugs were new this year and not used much. A few mechanically minded people i know have looked at it but weren't able to sort it. I can't afford to have it repaired by the nearest mechanics as they charge rediculas amounts, and the other mechanics is very busy for a month or so. So i'm going to try and do it myself if your brains can help me.


Anybody got any suggestions on how to sort it??


Regards

Cammy

[Nos4r2]

Originally Posted by camtheribman

Hi there, again my engine is playing up and not running on all 3 cylinders. I have tried bleeding the carbirattors to make sure there is no gunk in them, they were fine. The spark plugs were new this year and not used much. A few mechanically minded people i know have looked at it but weren't able to sort it. I can't afford to have it repaired by the nearest mechanics as they charge rediculas amounts, and the other mechanics is very busy for a month or so. So i'm going to try and do it myself if your brains can help me.


Anybody got any suggestions on how to sort it??


Regards

Cammy

No-you haven't given enough info.
Need to know:-

Which cylinders is it running on,
Does it have a spark on all 3 HT leads and plugs (test all on a 'known good' source, IE a cylinder that's firing)
Do you have a fuel filter/water trap?
How old is the fuel?

[camtheribman]

Originally Posted by Nos4r2

No-you haven't given enough info.
Need to know:-

Which cylinders is it running on,
Does it have a spark on all 3 HT leads and plugs (test all on a 'known good' source, IE a cylinder that's firing)
Do you have a fuel filter/water trap?
How old is the fuel?

I don't know the answer to the first two questions. I have an inline fuel filter. The fuel was a few hours old when it stopped working, i have used it in other engines and it's been fine.

[mdt]

Perry

I will be down this evening. will be about to give you a hand properly to see what is going on or not with the sparks etc.

[camtheribman]

Originally Posted by mdt

Perry

I will be down this evening. will be about to give you a hand properly to see what is going on or not with the sparks etc.

Thanks matt. What time? I won't be about for long as i have my maths exam tomorrow.

[9D280]

I failed one of them a few years ago by playing around in boats the day before......

At risk of sounding like someone's dad, the rib will still be there on Saturday........

[camtheribman]

Originally Posted by 9D280

At risk of sounding like someone's dad, the rib will still be there on Saturday........

Care to explain?

[9D280]

give it another 25 odd years and all will become clear........

[camtheribman]

Originally Posted by 9D280

give it another 25 odd years and all will become clear........

Erm ok

[spartacus]

Originally Posted by camtheribman

Hi there, again my engine is playing up and not running on all 3 cylinders. I have tried bleeding the carbirattors to make sure there is no gunk in them, they were fine. The spark plugs were new this year and not used much. A few mechanically minded people i know have looked at it but weren't able to sort it. I can't afford to have it repaired by the nearest mechanics as they charge rediculas amounts, and the other mechanics is very busy for a month or so. So i'm going to try and do it myself if your brains can help me.


Anybody got any suggestions on how to sort it??


Regards

Cammy

First thing to do is check you're getting a spark on all cylinders. Rough idling could be a number of factors, either fuel related, in the respect of the fuel itself, the carburettors, fuel pump, etc. Because it's running on at least 2 cylinders - it seems to be electrical related, and not necessarily fuel starvation.

Check for a spark first. No spark, and I'd look for loose electrical connection. Just checked my manual - this relates to the ignition coil, source coil and pulsar coil. In addition, check the connections to the CDI unit are in good condition.