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1996 Yamaha 200HP Surge Issues

F

Fr3shJiv3

New member
I need some suggestions please.

This weekend I replaced the fuel pumps, fuel filters and put sea foam in.

I took the boat out Sunday and still have the same issues.

1. When I start the boat the RPM's are at like 60-70 at idle. When I take off they are at 80 and higher.

2. Other times I can start it and the RPM's are at 20-40.

3. When I plane out the RPM's seem to still be running very high and if I trim the motor all the way down it seems to lower the RPM's

Do you think my motor need to be adjusted to sit lower? Could it be my prop? I don't have the cash to bring it into a place to have it fixed and am trying to fix as much as I can first.

Any help would be great. Thanks
 
I'd look at cleaning your carburetors as a good first step. Seafoam can help with some cleaning, but only a carb removal and thorough cleaning can assure they are ok. That's assuming you have an engine induced surge.

But, it also appears that your prop might be ventilating (blowing out) - and letting the engine rev too high. I'm assuming all your RPM specs are x100. If so, 8000 is way too high for your engine. I didn't look, but I'd expect WOT to be somewhere in the 6k range for max.
 
freeportd said:
I'd look at cleaning your carburetors as a good first step. Seafoam can help with some cleaning, but only a carb removal and thorough cleaning can assure they are ok. That's assuming you have an engine induced surge.

But, it also appears that your prop might be ventilating (blowing out) - and letting the engine rev too high. I'm assuming all your RPM specs are x100. If so, 8000 is way too high for your engine. I didn't look, but I'd expect WOT to be somewhere in the 6k range for max.
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Thanks for the info!!

What are you supposed to do if your prop is ventilating (blowing out)?

Would it be alright to take the boat out before I clean the carbs if I don't run the boat fast or could I do damage?
 
To check engine height, put your engine trimmed vertical on the trailer and then put a straight edge of some sort along the bottom of the hull V and see where that hits the engine. If the engine is mounted directly to the transom, the normal engine height would be with the anti-cavitation plate level with the bottom of the hull V. If you are higher than this, it could explain your prop ventilating. Are you trimming your engine right down when you take off?
 
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