I changed the fuel pump on my truck. But now there is no power going to the new fuel pump. I've changed the fuel system relay, but still nothing. I have a mechanic trying to figure out what happened. But he can't seem to figure it out either. What can it be????
My car has an automatic transmission.
At key on, the fuel pump is normally only powered momentarily to pressurize the system. If you are testing during this brief interval, you have to apply a volt meter at the instant the key is turned on. Otherwise, the circuit will be normally open until the vehicle actually starts. If you are detecting momentary power during that window, then your no start condition is "probably" not related to a fault in the pump circuit.
If you detect no power at ANY time to the pump (including during key on), your only recourse is the Factory Service Manual wiring diagram. With the diagram in hand, you have to trace the fuel pump circuit from the power source to find the interruption. There may be a fusible link in the circuit; also check the pump ground. Obviously check the wiring harness and plug connections as those were handled during the repair. You can probe the new motor terminals to see if they are open. If the motor is good, you should find a small winding resistance of maybe 3 ohms or so (varies from pump model to pump model).
If you desire a mobile repair for this, simply request an electrical diagnostic and the responding certified mechanic will get this taken care of for you. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.
Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing