Lift Pump Operation

[kbates]

Does a lift pump work all the time when a 6.5 is running. I was checking mine today and it just quit working while I had my hand on it. I pulled the connector apart and found power at the connector. Hooked it back up and pump was working again for 3 minutes and then no clicking again. Is this a relay problem, a lift pump problem or a oil switch problem. Truck starts and runs perfectly. I have always just felt the pump and when I feel it pulsating, I think everything is OK. When I put a fuel pressure guage on I have about 3 lbs and then nothing. Any Ideas. Thanks 95 GMC 4X4 F Series Engine in a 2500 Series truck.

[sixnickel]

The lift pump runs all the time the engine is running! All the time!! With the engine running, back probe the connecter at the pump with a volt meter, you should have running voltege of about 13.5 to14.3 volts. Probe both wires at the same time to get your hot and ground. If the pump stops running and you still have voltage at the connector the pump is bad! If the voltage goes away the problem is in the OPS or the relay. Good Luck