1988 Ford F-150

Tiny
SHANEPAYE
  • 1988 FORD F-150

Electrical problem
1988 Ford F150 V8 Four Wheel Drive Automatic 120000 miles

I have a 1988 ford f-150 with the 302, every morning I go out and the truck will start right up and run great all day, when I shut it off it will not start again unless I pull the fuel pump relay out. After it restarts I have to plug it back in and it will continue running fine until I shut it off again. When I try to restart it I do have spark at the plugs, but I can smell the fuel like it is flooding. Any ideas?

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Thursday, March 5th, 2009 AT 5:50 PM

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Tiny
MERLIN2021
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http://www.2carpros.com/how_to/how_do_i_check_a_relay.htm
If the fuel pump runs with the key off, replace the relay and check the fuel pressure regulator. Pull the vac line off and if there is any gas in it, change the FPR.
Test pressure and regulator this way.
http://www.2carpros.com/car_repair_video/test_fuel_injection_pressure.htm

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Thursday, March 5th, 2009 AT 6:03 PM
Tiny
JAMES W.
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First thought is you have injectors bleeding down and flooding the engine. Does your engine oil smell "gassey"?

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Thursday, March 5th, 2009 AT 6:03 PM
Tiny
SHANEPAYE
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Yeah I can smell gas in the oil, does that mena new injectors or whats the easiest way to fix that?

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Thursday, March 5th, 2009 AT 6:18 PM
Tiny
MERLIN2021
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The smell can also be from just cranking the engine without it starting. Do a fuel pressure test and leakdown test with a fuel pressure test guage, it's the ONLY way to find leaky injectors. You do it by watching the gauge for five minutes with the key off, if it losses 5lbs of pressure over the specified time, an injector is leaking.

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+1
Thursday, March 5th, 2009 AT 6:22 PM
Tiny
SHANEPAYE
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Awesome thanks a lot for the help

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Thursday, March 5th, 2009 AT 6:37 PM
Tiny
SHANEPAYE
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I'm sure its an injector, is there any way to fix or is that a replace part?

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Thursday, March 5th, 2009 AT 6:40 PM
Tiny
MERLIN2021
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Is the truck getting missfires on any particular cylinders? Those would be the bad injectors, replacing is the only fix for bad injectors, but I still advise the testing.

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Thursday, March 5th, 2009 AT 6:47 PM
Tiny
SHANEPAYE
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It doesn't seem to be misfiring at all, when it starts it runs great, its just the restarting that is the problem. It just cranks over and over unless I shut the fuel pumps off manually by pulling the relay, once it starts again I have to plug the pumps back in before it dies again

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Thursday, March 5th, 2009 AT 7:07 PM
Tiny
JAMES W.
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There is one thing here that puzzels me here. I've seen where 1 or 2 injectors will bleed down and when the engine is restarted a couple of cylinders will be flooded and will limp for a bit before they clear out. But I've never seen where all of a sudden "all" the injectors went bad to the point that the engine won't even fire. You may want to follow merlin2021's suggestion and run a fuel pressure bleed down test with a gauge. Keep us posted.

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Thursday, March 5th, 2009 AT 7:34 PM
Tiny
SHANEPAYE
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Yeah I will do the test and keep you posted, I guess I forgot to mention this all started after I degreased and washed the engine bay. But I checked all connectors and they are all dry and look good

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Thursday, March 5th, 2009 AT 7:37 PM
Tiny
JAMES W.
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Degreased and washed, huh. Have you checked all your fuses. Just a thought.

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Thursday, March 5th, 2009 AT 7:44 PM
Tiny
SHANEPAYE
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Well the truck has about 36 lbs of pressure at the fuel rail, it lost 4 lbs in 5 minutes, I started it and its running at 30 psi consistently, I pulled the vacuum line from the regulator and it jumps to 40 lbs with no fuel in the vacuum line. Yet still after the truck gets to operating temp and I shut it off it still won't start back up. Weak coil or ignition module? I'm stumped I don't know what the deal is

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Thursday, March 5th, 2009 AT 9:58 PM
Tiny
(HELP)
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Why would shutting fuel off help weak spark? After losing 4 lbs in 5 min - "I started it" you said - how much does it lose when fault occurs?

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Thursday, March 5th, 2009 AT 10:11 PM
Tiny
SHANEPAYE
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I don't know I was thinking to much fuel spark was to weak or not firing right under compresion. I'm out of ideas.

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Thursday, March 5th, 2009 AT 10:16 PM
Tiny
SHANEPAYE
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Oh and the fuel pump does not run with the key off, it runs how it supposed to

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Thursday, March 5th, 2009 AT 10:18 PM
Tiny
JAMES W.
  • MEMBER

We're missing something here. We need to look "outside the box" so to speak. When the engine is warm and you unplug the FP relay, does it start right up, or do you have to crank for a bit? Do you need to floor board it to get it started? Do you get a cloud of smoke out the tailpipe when it starts. These are the type of problems that keep me awake at night. Please advise.

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Thursday, March 5th, 2009 AT 11:18 PM
Tiny
SHANEPAYE
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Well any ideas? The truck will start first thing in the morning, after its warm it won't start, it just cranks over and over(with spark) ne one, any ideas

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Thursday, March 5th, 2009 AT 11:20 PM
Tiny
SHANEPAYE
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Um when I unplug the fp relay it does not start right up, it turns over 4 or 5 times then it starts. If I don't plug it back in right away it will stall again. Once I plug it in it runs good, no smoke, no misfiring, no rough idle, runs smooth as can be. It will run all day if I leave it running without any problems at all. But the second I shut her down, it does the same thing again.

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Thursday, March 5th, 2009 AT 11:22 PM
Tiny
JAMES W.
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OK, when we figure this one out, it will be for the record book. From what you've posted, the truck isn't flooding and the injectors aren't bleeding. You may have an injector or two that are weeping a little bit, but thats not why it won't start. Let's check injector pulse with engine warm and FP relay installed. If you have, or have access to, a "noid light", it just plugs into the injector connector, or you can use a regular "incandescent" test light. Try this and let me know if you get a pulse.

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Friday, March 6th, 2009 AT 12:16 AM
Tiny
SHANEPAYE
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Well i'll get back to it tomorrow, thanks for the help and I will keep you posted.

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Friday, March 6th, 2009 AT 12:28 AM

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