ok heres the deal on my 88 bronco with a 5.0L. i replaced the engine and i started it up right away. good thing. started it up again, worked just fine. i didnt run it but like 10 seconds each time. anywho when i did this all i had on was the water pump...so i put the rest of the crap on and i go to start it up and it just turns over. hmmm kinda confusing. i didnt change anything just put on the ac, p/s, alt, yada yada yada. well before putting on the accessories i pushed down on some little nipple thing on the fuel line to see if it was gettin fuel. sure enough it was, gas came bubling out. well, after the accessories were put on, no fuel came from teh nipple on the fuel line. so i checked the fuel pump. i turned the key to the "start" position and u usually hear a buzzin noise, which is ur fuel pump. well no noise. so i disconnected teh pump and hooked it directly to the battery, worked just fine... ok? so i tested to see if power was gettin to it, power was coming to it. ok? so i cleaned the connectors: still nothin. so i spliced the wires directly together. still nothing. i took the fuel lines off to see if fuel was comin out during this time when testing it. no gas, no flow. i have gas in the tank. fuel pump works. power is gettin to the pump bc i put the voltmeter up to it to test it. still no flow. i hope ive made this clear bc its real confusing to me. please help me out. i dont know what to do now. Thanks, David

 

Under EXACTLY what conditions did you test the pump for power, and EXACTLY how did you test it? If the engine isn't running, it will only come on for ~1 second each time you turn the key to RUN. Have you checked the inertia switch? The FP relay?

 

i had a friend turn the key while i held the voltmeter up to the wires. and if power is gettin to it, im assuming that the relay is ok. whats the inertia switch and where is it located?

 

I have an '86. On mine the inertia switch is located under the dash on the passenger side firewall.

But if your getting power to the pump, it's not the inertia switch. The inertia switch cuts power to the relay so it won't make it to the pump.

Do you have two pumps on that thing? Mine has an in-tank lo preassure pump and a frame mounted hi preasure pump.

Just had similar problems on mine which turned out to be a loose wire on the relay, and a broken fuel return line.

It didn't fire up until after I fixed the return line. Don't know if that's a feature or a coincidence.

Make sure all your fuel lines are hooked up, and check the tank pump. Your 20 seconds of run time may have been using up fuel in the lines and filters.

When fuel stopped coming out of the nipple on the fuel rail, did preasured air come out? If so I'd say the pumps working, but isn't getting any fuel.

In which case I'd check the lines, filters, and tank pump (if yours is set up that way).

 

There is a EEC test connector on the right side of the engine bay. You can jumper the fuel pump to on. Here is a link to where the fuel pump connector is. If it works here you have to start checking wires. let us know how it goes. <http://www.shotimes.com/SHO3eeccodes.html>

 

If the pump is receiving 12V (AT the tank connector) but won't make any pressure, then the pump is bad. Nothing else matters. Put a pressure gauge on the fuel rail to confirm it.