Four Winns

[bowrider95]

I have a 1995 Four Winns with the Cobra 5.0 and the Volvo Penta SX outdrive. I had to replace the outdrive a few years back and ever since then the boat just acts as if it just doesn't have much power. Can the wrong gear ratio cause this problem? The boat max speed was only about 28 and the RPM's was at 3500. This is just puzzling. Where should I start? It has new plugs and plug wires. Engine seems to run good.

 

[southkogs]

Yes, gear ratio can effect the power you get. Your RPMs at WOT are low.

What is your current gear ratio, and what is your prop size and pitch?

 

[bowrider95]

We verified the gear ratio is 1:66. The prop on the boat is a 14.5 X 19. We are now suspecting a fuel pressure issue. It will get up to 4800 RPM when here in the yard. We are thinking under load it might be starving for fuel. Any Ideas on how to check? We replaced the fuel pump a while back. This boat has been a project. We replaced the transom and stringers the fuel pump and had the carburetor rebuilt.

 

[garbageguy]

... It will get up to 4800 RPM when here in the yard....

Rev'ing it that high with no load, might not be the best thing

 

[bowrider95]

It was a very quick test and back off.

 

[southkogs]

Okay - for sure not an expert on the Cobras; but I'm thinking the 5.0 was a 1.5:15 overall. Might want to confirm what it's supposed to be.

Not sure why it would starve for fuel under load, but not off the trailer.

 

[bowrider95]

I have verified the gear ratio that is supposed to be and it is the 1:6. I looked up the drive number that is on top of the engine.
As for the fuel starve we are going to take it to the lake to try and verify if it is getting enough fuel by a inline fuel pressure gauge and vacuum test on the tank side.