Gas Tank Fuel Pump

[shepadi1]

purchased car off lot and was told had problems with fuel pumps" stopped working". this bronc is '88. checked and replaced gas tank lines and fuel pumps"lots of varnish everywhere' don't believe anything had ever been replaced. Car starts great and then gas tank fuel pump quits. sit awhile and starts again and then same thing. Before i pull everything apart again is there something i am missing

 

[STLKIKN]

If the fuel pump works with the initial turn of the key, the "start cycle" is good.
(this 3-5 second "burst" primes the fuel system at start-up)
This also confirms that the wiring to the pump is good, it uses the same circuit.
To double check this circuit, without starting the truck turn the key to the run position, both pumps should run for a couple of seconds, and then quit.

Now to isolate the problem...
Is the inertia switch functioning properly??
Are all fuses good?
Have you checked/ replaced any of the relays?
Are all grounds in good condition (including the computer case ground and the tank ground)

 

[billybroncojr]

Had a similar problem with the BII I had. It would shut the fuel pump on the frame rail off at random. Pump was good, relays were good, turned out to be wiring. I ran a seperate wire from the relay to the pump and it worked fine. Your's sounds more like the relays to me, if I had to guess. There are relays on the passenger side fender wall, make sure these are in good working order.

Good luck,
Jeff

 

[fbrown3]

sounds like the relay to me also, if not that I would look for sediment in the fuel. On old gas stations the inside of the tank will begin to break down and deposit a very fine sediment into the gas . This will stay suspended in the fuel but will clog a filter when the car dies- the sediments will settle and the car will start and run again for a while. Hope this helps, the sediment is usually a brownish color