Volvo 5.0GX1 Fuel Pump

moorish

Cadet
Joined
Jul 26, 2011
Messages
9
I need help/advice please. I own a 24foot Daycruiser (Vintage Sunseeker Mexico 24). I fitted a new engine a few year ago (Volvo Penta 5.0 GXi). When complete I started the engine and it run well for a few minute and stopped. I then realized I had left the fuel valve on the off position. I turned it on and after a few tries the engine started ok. My question is that after using the boat for a few years I am not convinced that it delivering it max power. For a 280hp engine and a boat that weighs approx 5000lbs it should be nearing the 45knts mark. It has never gone over 34knts even with a clean hull.
I remember reading in the Engine Installation guide that it could damage the fuel pump if the engine is run with the fuel valve shut. The engine starts and accelerates smoothly it just that the speed/power is not there.
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: Volvo 5.0GX1 Fuel Pump

What is your max WOT (wide open throttle) rpm? What outdrive and gear ratio do you have?
 

Maclin

Admiral
Joined
May 27, 2007
Messages
6,761
Re: Volvo 5.0GX1 Fuel Pump

I think 35 knots in a 24 footer with a 5.0 is not too bad. That is almost 40mph. The drive ratio of 1.78 seems too high to me for a 5.0 though, seems like that is big-block ratio territory. What propset are you running?
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: Volvo 5.0GX1 Fuel Pump

1.78 is for the big blocks, you should have a 1.95:1 ratio for a 5.0 or 5.7 . Especially with a 5.0.
You may get the rpm in range by changing props, but you will loose top end. Probably have a weak hole shot too.
 
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