5.7 Volvo Penta Fuel Problem???? Help!

[utkayaker]

I have a 5.7 GXI in a 24' Four Winns boat. Getting ready for this year and need to get this fixed.

Last year the engine started sputtering when going from idle to full throttle. It idles fine, but absolutely will not move up smoothly to full power so there is no way we can pull a skier. Even pulling a tube is very sporadic until it finally settles down. I can manipulate the throttle and eventually get it to run full speed and it sounds fine.

I thought maybe I had water in the fuel. I haven't drained the tank but I pulled the filter and replaced it and it had no water in it whatsoever. I also replaced the spark plugs in case it may be an ignition problem.

I am not sure how I can diagnose the problem and would welcome your insights.

I really want to fix this myself but don't want to buy a thousand new parts to figure it out...

I saw about using a pressure gauge but don't know exactly what pressure gauge to get and what the specs should be for this engine.

Fuel pump?
Ignition?
Pressure regulator?
Still water in it???

Thanks!!!

 

[el_pescador]

Do you have a manual that you can use? SELOC for example? That would help you to do most of the troubleshooting.

Also, you may want to check the anti-syphon valve in the fuel tank, and also any strainers/filters you may have installed both on the suction and discharge sides of the fuel pump.