Motor Problems

[locodave]

Hi guys,

The other night while driving back, my friend realised the motor was running a little rough. 10mins into the trip the boat just slowed down on it's own, it lost power. Didn't stop completely though. Felt like it was running on 3 cyclinders, and dropped to two.

We checked fuel lines, prop etc. Everything was fine.

We strolled home and then out of nowhere it felt like the 3rd cylinder fired up again and we got more power.

I managed to turn the engine on and off no problems through out that situation.

Got home and checked the spark plugs, the top two wer moist, but the bottom one was completely dry. Is that a clue what could be wrong?

Thanks for any help

[locodave]

By the way it's a 40Hp Mariner 2001 oil injected 2 stroke.

[Geoff]

Moister on the plugs does not sound good. I had something similar happen a few years back. Repairs were not cheap so traded it in on a new motor

Suggest a PM or call to Craig at Huett Marine

Geoff

[a boat]

Hi Dave, if I was your mate I would do a compression check and also a spark output check and if he has three good spark and three good compression than that is a start and we can go from there. Strange that 2 out of the 3 were wet which tends to mean you have "no fire" or spark to those cylinders because that engine will not run on one cylinder. they will run badly on two but on one they will just stop.

Do the above and let us know what he finds.

Cheers,

Huey.

[locodave]

Thanks for the reply Huey. I will do the compression test and the spark test this weekend and see what happens.

Are you saying possibly there could be something wrong with the 3rd cylinder? The one where the spark plug was wet?

Should I just clean up the spark plugs with a metal wire brush and give it a run and see what happens?

Problem is, it's running fine now too, so it's hard to diagnose.

[a boat]

Hi Dave, in your first post you say 2 plugs were wet which can be because those cylinders do not have spark but as i said the engine would not run if 2 out of the 3 cylinders were not doing their job. Makes more sense if only one plug was wet and yes having an engine misbehave intermitantly is a real pain.

Cheers,

Huey.