Hello,

Thanks for the updated information.

The Volvo Penta fuel cells are a very common failure item (typically due to sitting and the fuel turning bad or water intrusion), we have replaced over 3 dozen fuel cells this summer alone. The whining noise is a common sympton of a failing fuel pump as is the extremely hot fuel pump. The slow dying symptom of the engine also points to a fuel related issue instead of an electrical issue (electrical/ignition system issues are usually quick and fast as if someone is turning the ignition switch on and off).

Being that you have an MPI engine, your fuel pump pressure at the fuel rail should be 50 - 60 PSI on your Volvo Penta 5.0GXi MPI engine to run correctly. I suspect that your low fuel pressure pump may have failed (or is failing) and the high pressure fuel pump is overworking and struggling to maintain any fuel pressure (low pressure pump is the pump on the left side and the high pressure pump is the pump on the right side as you are facing the front of the engine looking at the fuel cell).

The best advice would be to have the fuel pressure checked on both the low and high pressure fuel pumps (low pressure fuel pump spec is 8 PSI +/- 4 PSI), the high pressure spec is 50 - 60 PSI as mentioned above.

See picture below for the two locations to check the fuel pressures on a typical 5.0GXi MPI engine (the red arrows pointing to the schrader valves where the fuel pressures are read, early models may not have a provision to check the low fuel pump fuel pressure at the base of the fuel cell)...

If the low pressure pump is not within specs, you will need to replace the complete fuel cell assembly as the low pressure pump is not available as a replacement part. If the low pressure pump is within specs, and the high pressure pump is not, you can theoretically replace the high pressure pump as there is a replacement high pressure pump available. With that said, I will tell you that I've gone that route and replaced just the high pressure pump in the past only to have the low pressure pump failed shortly thereafter (becomes very expensive replacing multiple pumps), my advice would be to replace the complete fuel cell assembly if the fuel pressures are not within specs with either pump (I suspect that the pressures will not be within specs since the engine only runs for a few minutes before stalling).

Before proceeding with a fuel cell replacement, you need to ensure that there are no restrictions in the fuel delivery to the fuel pump as your pressures readings will obviously be incorrect. Having twin engines makes it nice for diagnostic purposes, you can swap out the fuel cells between the two engines to confirm if indeed the questionable fuel cell is bad.

I hope that you find this information useful, thank you again for your question.