91 Ford Bronco fuel pump problem?
My fuel pump is running continuously with the ignition switch on. It is supposed to run for about 2 seconds and then shut off. Then the truck runs off of vacuum to feed fuel to the motor. This is something that has just started. The truck will not start when this occurs. It is a 91 Ford Bronco with 351 EFI. Any ideas what would be causing this?
Comments
The fuel pump timer is in the PCM. If the pump runs continously you more than likely have a fuel pump relay that is sticking. FYI....the fuel is never drawn by vacuum...vacuum adjusts the fuel pressure regulator but the pump runs when the vehicle is running. The first 2 seconds are just to prime the lines.
91 Bronco
Did you check the fuel pump safety switch to see if the little red button has popped out? If so, push the reset button back in and it should be fine. These can be very sensitive. My sister's 93 T-bird used to pop it just going over potholes in the road.
Fuel pressure regulator is bad and dumping fuel back into the tank.
Stuck relay or a bad processor