yamaha 40 firing issue

camtheribman · 20 May 2010, 13:18

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 · 20 May 2010, 14:05

Quote:

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 · 20 May 2010, 14:15

Quote:

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 · 20 May 2010, 14:36

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 · 20 May 2010, 14:41

Quote:

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 · 20 May 2010, 16:01

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 · 20 May 2010, 16:15

Quote:

Originally Posted by 9D280

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

Care to explain?

9D280 · 20 May 2010, 16:25

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

camtheribman · 20 May 2010, 16:28

Quote:

Originally Posted by 9D280

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

Erm ok

spartacus · 20 May 2010, 22:35

Quote:

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.

camtheribman · 20 May 2010, 22:40

Quote:

Originally Posted by spartacus

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.

Thanks for the help, i will go tinker tomorrow evening.

Cammy

Nos4r2 · 21 May 2010, 00:05

Quote:

Originally Posted by camtheribman

Thanks for the help, i will go tinker tomorrow evening.

Cammy

Find out exactly what model it is.If it's a spark related issue, I should have the CDI and coil test procedures/figures around somewhere. You'll need to know how to use a multimeter though.

camtheribman · 21 May 2010, 08:04

Quote:

Originally Posted by Nos4r2

Find out exactly what model it is.If it's a spark related issue, I should have the CDI and coil test procedures/figures around somewhere. You'll need to know how to use a multimeter though.

I know it was made in 1990 if that helps, i know how to use one of those, we use them in physics

Cammy

spartacus · 21 May 2010, 11:24

Quote:

Originally Posted by camtheribman

I know it was made in 1990 if that helps, i know how to use one of those, we use them in physics

Cammy

Start with the CDi and charge coil as they are easily accessible. You will need figures from workshop manual to test. Failing that the pulsar coil is located under the flywheel - but you need a special tool to hold the flywheel and another one to extract it. The pulsar coil is expensive, so more than likely you'll have to source it second hand, however cross that bridge last.

Read a post somewhere on a Yammie 90hp that wasn't sparking on number 3 cylinder and the CDI and charge coils checked out okay. The fault was eventually traced to the pulsar coil.

Philozzie · 15 July 2010, 11:31

Hi Spartacus,

I have a 40 Veto that i am having similar problems with, i was wondering if you have the figures to test the CDI unit?

My outboard has run poor since i bought the boat.

I found two pilot Jets were missing in two of the three carbies. I took the boat out to find once jets were replaced to find it was still running rough ( no power, hard to start, poor idle excessive fuel consumption )

Then all of a sudden the motor sprung into life while at 3/4 throttle, this has since been sporadic and the motor still runs poor at times. Have been told it may be the CDI unit which is unservicable.

Any help would be greatly appreciated

Phil

9D280 · 15 July 2010, 12:34

[QUOTE=Philozzie;360777]
Then all of a sudden the motor sprung into life while at 3/4 throttle, this has since been sporadic and the motor still runs poor at times. [QUOTE]

Intermittent stuff is most likely to be electrical. Even stuff as simple as a damp coil drying out as the engine warms up. There are a remarkable amount of connectors between the trigger coils and the spark plugs. A dodgy connection on any of them will cause it to run rough.

[QUOTE=Philozzie;360777]
Have been told it may be the CDI unit which is unservicable.
[QUOTE]

Yep, so they can charge you bucketloads of cash to supply a new one!

9D280 · 15 July 2010, 12:42

Quote:

Originally Posted by camtheribman

I know it was made in 1990 if that helps,

Did you ever get it running?

Easiest way to find out which cyl isn't firing on a 2 stroke is run it for 5 mins and then take the plugs out. The manky oily one is the one that ain't working.

Simple / cheap way to find a duff electrical ignition component is once you have a plug oiled up, clean it, and swap it with one of the others. Run for 5 mins, see if the oiled plug follows the plug. If yes, the plug is gubbed. If not, clean the plug again move one component back in the system (HT lead , may be part of the coil assy, whatever is next) and swap them. Once again, if the oily plug moves, that's your duff part, if not, clean it & carry on 'till you run out of things to swap.

Worth going through with WD40 and cleaning all connections first tho'.

camtheribman · 15 July 2010, 15:22

Yeah she was running beautiful thanks to david anderson marine. But someone then put a fair bit of water into the fuel so i just have to clean the filters now.

spartacus · 15 July 2010, 22:25

Quote:

Originally Posted by Philozzie

Hi Spartacus,
I have a 40 Veto that i am having similar problems with, i was wondering if you have the figures to test the CDI unit?
Phil

Sorry, no. Used to have a mint 1995 Yamaha 40V 3 cylinder outboard, but sold it. You can pick up a workshop manual of Ebay.