1998 4.3L GL Fuel Pump Issues

[djrevkev]

Wondering if anyone has ran into this...I just replaced engine with a reman 4.3L. I cant get fuel to carb. I believe this pump is supposed to run only when cranking. It does not run when cranking engine. DVOM shows 10.9 volts at the pump connection yellow/red wire when cranking. If I jump relay pins 30 and 87 the pump will run but wont pull fuel from tank. If I supply power and ground straight to pump/pump will buzz but still not pull fuel. Tank is full and fuel filter is new and filled with fuel. I believe I may have 2 issues. My pump is bad since it wont pull and what would be the reason why my pump wont run when cranking. I did also replace the fuel pump relay next to the pump with new just to be sure it wasn't that simple. Could the diode from the ignition switch to the relay at 85 be bad since it doesn't power up when cranking but still show 10.9 volts? im so stumped right now.

 

[Senior B]

Did the boat sit for a very long period of time? There is a antisiphon valve that the fuel line connects to at the tank and it could be stuck in the closed position. Also if any wiring has been messed with and the wires to the pump are swapped, it could run backwards and yes, the pump itself could be bad.

 

[alldodge]

Agree antisiphon valve, or tank pickup tube, fuel filter clogged or other restriction

I believe this pump is supposed to run only when cranking

The relay gets power from the Yellow/Red and thru the diode when cranking. After motor starts, the alternator supplies power to keep the relay energized with the green wire thru the other diode

 

[djrevkev]

Did the boat sit for a very long period of time? There is a antisiphon valve that the fuel line connects to at the tank and it could be stuck in the closed position. Also if any wiring has been messed with and the wires to the pump are swapped, it could run backwards and yes, the pump itself could be bad.

Did the boat sit for a very long period of time? There is a antisiphon valve that the fuel line connects to at the tank and it could be stuck in the closed position. Also if any wiring has been messed with and the wires to the pump are swapped, it could run backwards and yes, the pump itself could be bad.

The boat sat from September 2020 to June 2021 last week after I dropped the new motor in. I can pull fuel thru the line to the tank. I tried to suck the fuel up thru the line and hook it back into the pump. I ate 93 octane

 

[djrevkev]

Did the boat sit for a very long period of time? There is a antisiphon valve that the fuel line connects to at the tank and it could be stuck in the closed position. Also if any wiring has been messed with and the wires to the pump are swapped, it could run backwards and yes, the pump itself could be bad.

The boat sat from Aug 20 to Now

 

[alldodge]

Disconnect the fuel line from the tank. Use a gas can and a longer piece of fuel line and place line in the can. See if it clears up

 

[djrevkev]

Just updating that I replaced the fuel pump and all is good now. Thanks for the help. Happy father's day to all with children or your boat!!