Boat stuttering at speed

[steve r]

Hi all

I have a yamaha 50 2 stroke.

Very intermittently, I am getting a stutter at full throttle. It seems to happen when running into the waves.

I have replaced fuel pump, but still seems to be there.

Any suggestions what this could be?

Apart from this , it runs beautifully!

Thanks

 

[rianc]

Hi Steve, lets open the discussion and fault finding. You have replace the fuel pump, thinking it might be fuel related?
I have two questions please.
1. What rpm do you run when this starts to happen?
2. On Flat waters, does it do the same?

a. check the throttle balance on the three carbs, butterflies opening. On might be over adjusted an will typical simulate "choke"

b. The float levels on the carbs is out, needle and seat dirty.

In short it could be starvation, air leak on fuel connections between the carbs.

 

[steve r]

Thanks for the reply. I think it is fuel related too.

I did two runs down the same stretch of the lagoon.

On the downwind run flat out, no problems. Turned and ran back and on both runs felt the stutter. Don't think it is a misfire, just a drop in power for half second and then back again.

Not sure of the revs as don't have a review counter.

There was a bit of dirt in fuel filter when checked before going out.

Maybe a carb clean is in order!

 

[willem wikkel spies]

steve

basics first!
please stay away from trying to set or adjust carb float levels.
they hardy get out!

this would be my very last option.

a possible needle and seat issue, perhaps.

a drop in rpm just for s seconded could be dirty carbs/ running lean etc.

 

[steve r]

I'm still getting this problem after cleaning carbs. It seems to be a misfire .

When I checked engine after I came off water , I got a shock from the one spark plug when I touched the boot.

Could it be a dodgy wire or boot?

Thanks for help!

 

[rianc]

Earth?

 

[Nix]

Hi,
Could be spark plug lead breaking down under load.Could also be a coil breaking down.
Cheers
_seal1_::slr::::tight:

 

[WILD]

Steve.
Have you found the problem. Mine is doing the same

 

[tackle addiction]

hi steve I will look at your boat engine with the greatest of Plesure.

 

[steve r]

I now see the tell tale is not pumping water properly. Think will take her in and have her looked at. Any mechanics recommended in langebaan?

 

[trier]

Leon 0722296796
Neville 0825705613

 

[steve r]

Thanks

 

[steve r]

The impellor was in very bad shape, so possibly the boat was running in limp mode.

Had full service done , so taking her out today to see if sorted. Holding thumbs!