1989 Ford F-150 Fuel Pumps Shutting off

Tiny
DALE8809
  • MEMBER
  • 1989 FORD F-150
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 300,000 MILES
The truck will not start. When I turn the key on the fuel pumps run for a few seconds and then shut off. I tested voltage, grounds, and resistance at different pins on the EEC computer plug. Everything checked according to fordfuelinjection. Com. When ground to the #6 pin of the EEC test plug the fuel pumps run nonstop. So, I replaced the EEC computer and am having the same result. The fuel pumps continue to shut off and I don't know what else the problem could be. Please advise. Thanks.
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Tuesday, August 18th, 2009 AT 4:58 PM

8 Replies

Tiny
BLACKOP555
  • EXPERT
Hthe fuel pump is only supposed to run for a few seconds and turn off.

It gets the pressure up and then turns off untill you get a response from the ignition ssytem to turn it back on.

Is the fuel pressure building?
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Tuesday, August 18th, 2009 AT 5:27 PM
Tiny
DALE8809
  • MEMBER
I say no because I can take the fuel line off on top of the tank and it still does the same thing. I read that with the fuel line off it should continue to pump, is that wrong?
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Tuesday, August 18th, 2009 AT 7:16 PM
Tiny
BLACKOP555
  • EXPERT
Well unles your vehicle has a sensor rigged on the fuel line for pressure that cuts out the relay then no there is no way disconecting the line will do that. It turns on primes the rail and turns off should turn off when you hear the relay click off. Its located near the air cleaner box.
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Tuesday, August 18th, 2009 AT 7:36 PM
Tiny
DALE8809
  • MEMBER
I dont think I was clear enough in my explanation earlier. The fuel pump is supposed to pump until proper pressure is built, no? So if you remove the fuel line, then the pressure cannot be built and pump should run and run, right? In oher words would the fuel pressure regulator still cut off pumps with fuel line disconnected? It still stops running.

Also, so long as I ground pin #6 on the EEC test connector, the pump will run all day.

We know the results of that test mean: I am getting power from EEC power relay to fuel pump relay coil, from the Fuse link at starter solenoid to fuel pump contacts common pin, from the ignition swith to EEC power relay coil, also that the fuel pump and EEC power relays are OK, Inertia swith is OK, selected fuel pump is ok, wiring and plugs are ok from fuel pump relay to pumps, ground for pumps is OK, and I am getting power from Ignition switch to EEC Power Relay Coil. Also, the test bypasses the EEC computer. That is why I replaced the EEC computer. So why does it work when grounding that pin only? (And could it be the Stater bad?)
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Tuesday, August 18th, 2009 AT 9:16 PM
Tiny
BLACKOP555
  • EXPERT
When you bypass it it just turns on the system. The fuel should stop. And then turn back on when engine is cranked. If it keeps running. Like in an accident and the relays and the pump still runs but the line is split it will keep pumping gas. Which is a no no.

To find out if its good or not you need a fuel pressure check guage
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Friday, August 21st, 2009 AT 12:37 PM
Tiny
RASMATAZ
  • MEMBER
Use a test light check for power before and after the blue fusible link 20ga at the starter relay if okay instead of pin 6 go to pin 20 and ground it and tell me what happened.
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Friday, August 21st, 2009 AT 1:10 PM
Tiny
RASMATAZ
  • MEMBER
Sorry I cannot highlight the circuitry-not allowed


http://www.2carpros.com/forum/automotive_pictures/12900_fp1_19.jpg




http://www.2carpros.com/forum/automotive_pictures/12900_fp2_9.jpg

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Friday, August 21st, 2009 AT 1:15 PM
Tiny
MERLIN2021
  • EXPERT
Will it run if you feed it some gas by hand? Could be a bad distrib, or ign mod. Also this old, check PCM power and grounds near battery.
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Friday, August 21st, 2009 AT 2:05 PM

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