Starving for fuel at high R.P.M.?

W

Wilst

Recruit
Joined
Jul 1, 2011
Messages
3
I have a 2001 Volvo Penta 5.7GSI. Everything works fine at idle, mid rpm, and 3/4 throttle. At almost full throttle, the motor starts pulsating & looses power. Like it is running out of gas. Two different, local, marine dealers have told me it is the high pressure fuel pump. (two fuel pumps on this unit). I replaced the high pressure fuel pump, but to no avail, it didn't solve the problem. Would it be the low pressure pump, rev limiter, or what? Thanks for your help.
 
B

BamaCharlie

Cadet
Joined
Nov 4, 2010
Messages
17
Re: Starving for fuel at high R.P.M.?

After it bogs down at wot does it run ok if you back off to 1/2 or 3/4?
If not what is the max rpm you get before it bogs down again?
I had a issue with my bogging down and then would not go over 2500 rpm's without boging down again. (1997 5.7 Gli)
Long story short after the shop tried a lot of things it turned out that the engine would enter the "engine protection mode". The cause ended up being the oil sender.
At wot it would not get the oil rhat was needed and the engine shut down to protect itself.
Good Luck..
 
W

Wilst

Recruit
Joined
Jul 1, 2011
Messages
3
Re: Starving for fuel at high R.P.M.?

Last night we were just idling around the lake and it starting pulsating even at low RPM. I hope it will be the low pressure fuel pump. That's next to replace. Am I right?
 
W

Wilst

Recruit
Joined
Jul 1, 2011
Messages
3
Re: Starving for fuel at high R.P.M.?

Could someone explain how the duel high pressure fuel pump system works and why it requires two pumps. I have a 2001 Volvo Penta 5.7 GSI. The problem I am having is that the motor is starving for fuel. I have posted my problem earlier. Two marine dealers told me it was a bad high pressure pump. I replaced the pump, but it made no difference. I thought I could replace the "low pressure pump". The low pressure pump is not available, you have to replace the whole unit, which I did. I still had the same problem. Getting pissed, I started at the tank. There was a check valve fitting in the tank to stop the gas from returning to tank. ( check ball with spring) I remove the check valve & installed a straight thru fitting. I ran the boat & it preformed to what I would expect. With two electric fuel pumps, why couldn't it suck enough fuel to the motor.
 
gbeltran

gbeltran

Petty Officer 1st Class
Joined
Jul 12, 2009
Messages
283
Re: Starving for fuel at high R.P.M.?

Unfortunately electric fuel pumps aren't the best at drawing fuel through a line, that's why they are usually located somewhere below the top level of the fuel tank, at least in the automotive world. Not always possible in a marine app, and may not be allowed from a legal standpoint. The low pressure pump is to fill a reservoir that the high pressure pump can draw from. I think the problems surfacing are due to the excess alcohol in the fuels nowadays, it cleans the gunk out of the fuel system and it ends up clogging the inlet to the low pressure pump putting additional load on the high pressure pump, reducing the total volume available at any given instant. It's also possible some of the junk/varnish that would normally stay in the tank ended up in your anti=siphon valve making it harder for the pump to pull fuel through it, which is why fuel system maintenance in a boat is more than just the fuel filter. A boat engine operates in a harsh, high demand environment, small issues that wouldn't be apparent or an issue in a land based engine can be big issues in a marine environment.
 
M

MustangJAB02

Cadet
Joined
Aug 25, 2009
Messages
9
Re: Starving for fuel at high R.P.M.?

Check fuel filter or any type of fuel restriction in the lines. Have ran into this problem a few times.
 
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