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No Power to Fuel Pumps!

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Old 12-05-2013, 02:53 PM
LongE
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No Power to Fuel Pumps!

Hey guys, I have a 1988 F250, and have been trying to diagnose the issue for the last two days, have been reading hundreds of different forum posts, and I'm stumped. The truck isn't starting, cranks but its not getting fuel. When I turn the key the pumps aren't priming. I grounded the fuel pump pin on the self test and the pumps turn on. My inertia switch is not tripped, and I replaced the relay. Since the pumps power on when I ground the fuel pump pin what could it possibly be??? The EEC? Is that the only possibilty? please Help!! I really can't afford to pay an guy 100 an hour to diag it. Thanks!
 
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Old 12-05-2013, 05:10 PM
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cont.

Also, I checked the fusible links to the starter solenoid and had power on every one with the key in run. Checked all the fuses. I removed the fuel line before and after the high pressure pump, and get no flow at all. The filter was replaced recently. From what I understand the power comes from the starter solenoid, and eec to the relay? Relay to the inertia switch and pumps? Like I said, I grounded the self test and the pumps kicked on...I will solve the problem if it kills me! Haha, I just want to know if changing the EEC would be the next best step.
 
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Old 12-05-2013, 06:03 PM
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If you've got a service manual such as a chiltons or a Haynes, id start by tracing the circuitry and checking wires first, and then components down the line from the relay. Chances are its not the eec. . by spending 20 minutes reading wires out, you could save up to 200 bucks by simply repairing a wire versus throwing an eec at it.
 
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Old 12-05-2013, 08:51 PM
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Do you have any CEL codes?
 
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Old 12-05-2013, 11:49 PM
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I appreciate the replies, there is no check engine light on. I'm going to check the wires over again to see if I missed anything. There was no obvious damage in the wiring that I've seen atleast, but will definitely have another look before I swap out the EEC.
 
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Old 12-06-2013, 08:26 AM
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Sounds like a bad ECU to me.
 
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Old 12-06-2013, 10:16 AM
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I don't know if wire colors changed but just keep following the line.

If you can get your hands on a volt meter and or 12 volt test light see if you have key on cranking power on the red. and the yellow power wires , if so see if your getting power out of the relay to the inertia switch on the dark green/yellow wire.
 
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Old 12-06-2013, 11:13 AM
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Check the small black wire with a green stripe at the NEG post of the battery. Odds are it is either this wire not grounded or a bad ECM computer.



/
 
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Old 12-06-2013, 11:56 AM
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If he's grounding the pin on the Self-Test connector and it makes the fuel pumps run, why would he need to check the wiring downstream? That tells me his wiring, fuel pump relay and tank switch are good.
 
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Old 12-06-2013, 12:26 PM
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Originally Posted by jas88 View Post
If he's grounding the pin on the Self-Test connector and it makes the fuel pumps run, why would he need to check the wiring downstream? That tells me his wiring, fuel pump relay and tank switch are good.
Yes that what it says.
But if the ground wire at the NEG post is off or bad the computer will not have a ground to ground the fuel pump relay.
Not sure if the EEC Power relay uses the same wire at the NEG post or not.
If it uses the same wire then about the only thing it could be is the computer or a pushed out wire in the computer plug.

Now if he jumped pin#2 to Pin#6 in the test plug and the fuel pumps ran that would mean the ground at the NEG post is good also.
But I think he said that he only grounded pin #6.
 
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Old 12-06-2013, 01:44 PM
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Understood - thanks for the clarification, subford.
 
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