Loses power above 1/2 throttle

[delacruz4]

Last year I replaced engine on the boat, 1996 Volvo Penta 4.3L GL. After that, had some issues with water getting in the gas, fixed the problem and replaced electric fuel pump that had crapped out recently. Sounds good in neutral, starts up easily. However, took it out last weekend for the first time in 5 months, and it would lose power when throttle was moved past 1/2. At 1/2 throttle, 2,000 rpms, above that, rpms dropped, sounded like it wanted to cut out, not much power at all. However, when I would pump the throttle back and forth (not all the way, about and inch or two, but repeatedly), the boat would get up on plane and hit 3500 rpms for as long as I would pump it. Stop pumping, back down to 2000 rpms or less. Again, in neutral it doesn't have such an issue.

I have someone coming out to look at it, but I would like to have an idea of what to look for (in addition to the "Engine won't reach operating RPM checklist"). Thanks for your help!

 

[cooter2506]

Re: Loses power above 1/2 throttle

That list is the things to look for. It has it all in there trust me. GO thru it all and post your results if that doesnt work (Bet it does) post all your results here and we can look at them and help you out.

 

[delacruz4]

Re: Loses power above 1/2 throttle

Thanks, I know the list is very comprehensive. For that reason I was hoping that the specific symptoms (i.e. throttle pump effect) would narrow down the search.

 

[Bondo]

Re: Loses power above 1/2 throttle

For that reason I was hoping that the specific symptoms (i.e. throttle pump effect) would narrow down the search.

Ayuh,.... I hear your Carb, Screaming for a Rebuild or replacement......

 

[delacruz4]

Re: Loses power above 1/2 throttle

Thanks, that's what I'm thinking.

 

[ken_23434]

Re: Loses power above 1/2 throttle

When you are "pumping" the throttle back and forth, you are probably feeding the engine via the accelerator pump part of the carb. That part is intended to dump and extra shot of fuel into the carb when you first "smash the gas" to over come the initial inrush of air. So, by pumping the throttle, I think you are effectively manually feeding the engine fuel instead of the normal venturi effect through the jets etc.. in the carb. As Bond-o said, sounds like a rebuild time.