Fueling Issues

[Wakeman22]

I have a 2007 24Ve with the 360hp motor. Has a low pressure and a high-pressure fuel pump.

I have been chasing down what I believe to be a fuel problem. Symptom... Loss of power and fuel pressure based on running and a fuel pressure gauge. Changed the high-pressure pump as it sounded like it was going out and tapping on it would allow it run intermittently and it finally quit. Replaced it. Boat ran for a little while during a test then same symptom appeared. Loss of fuel pressure, knocking, rough and stalls.

So, I am down to the low-pressure pump now. Disconnected the line from the low-pressure to the high-pressure pump. Turned key on but no fuel while it runs for the first 10 seconds or so. Multiple repeats no fuel. Pulling the fuel to tank line off the pump and checking for fuel.

Question... Is there a check valve in this line to stop fuel from returning back to the tank? If I blow into hose towards tank it seems to be blocked... Like a check valve. If I suck it seemed to pull fuel, although I did not want to get a mouthful of gas, so I did not suck too hard.

Any ideas on troubleshooting? There are 2 wires on the bottom of this low-pressure pump. Does the polarity of these wires matter?

[h2o-ski]

Yes there should be a check valve to prevent fuel spillage in case of a roll over or sinking. The system is designed for the low pressure pump to pull fuel from the tank and then the high pressure pump to up the pressure required for fuel injection. High pressure pumps are not designed to pull fuel from large distances, rather push fuel.

The low pressure fuel pump, from your description is it running? I know that it pulls no fuel, but are you that is not the high pressure pump running?

[lee]

Any ideas on troubleshooting? There are 2 wires on the bottom of this low-pressure pump. Does the polarity of these wires matter?

Yes it does, if reversed the pump will try to run in the wrong direction.