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Fuel pump won't prime

RobertFord

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City, State
Amsterdam, Netherlands
Year, Model & Trim Level
1991 Ford Explorer XLT
Hi guys,

Today I finished up my project of swapping the heads in my X, just when was trying to start the X, the fuel pump wouldn't prima, but the engine would turn over.

We've tried a couple of things to see where the problem might be.
1. The fuse is fine
2. We tried shorting the inertion switch, no difference
3. We tried grounding the wire from the testing harness

In all occasions, the fuel relay would click, but the pump wouldn't prime. Checking with a volt meter at the inertia switch always showed 0 volts in result. This leads me to believe that the problem should be somewhere between the relay and the inertia switch. Or would it still be the relay itself?

Any thoughts are more than welcome, I'm pretty fed up with it not running..
 



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mgmgmg

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Plymouth, MN
Year, Model & Trim Level
'94 LTD '10 LTD V8
Do you hear a whine of the fuel pump in the key on postion? If not then its a fuel pump relay....
 






Roadrunner777

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94 4x4 Sport 88k
Check for voltage at the inertia switch when you turn the key to ON. There should be a roughly 1 second 12V pulse. In not, then search forward to the engine compartment. Otherwise, it is towards the fuel pump.

I'm trying to think of how a head job would cause this... puzzling.
 






RobertFord

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1991 Ford Explorer XLT
Of course all these steps are at the KOEO position :) it's very puzzling indeed. Just hoping it's not the fuel pump. Also, as it would be the first startup after the tear down. There are so much more variables that you're thinking of, while that may not be necessary.

I guess I'll be searching for a relay tomorrow, just sucks that a $5 part will run me about $30 + 1 week of waiting here in the Netherlands...
 












awood

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City, State
Kaysville, utah
Year, Model & Trim Level
94 XLT
Check out this link:
http://www.explorerforum.com/forums/showthread.php?t=142801
MrShorty describes grounding one of the connectors in the EEC TEST port that will turn on (and Keep on) the fuel pump for testing. As you're facing the TEST port, it's the connector on the far right hand side.

The link has very good info for fuel pump pressure testing.
 






RobertFord

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1991 Ford Explorer XLT
The relays are standardized. You can swap them around and figure out what is wrong.

Somehow, on my X, the three relays under the distribution box have different colors, but more importantly, different layouts of the pins (I looked ad swapping the AC and fuel pump relays) also there's a different indent on all connectors that prevent one plug from being inserted into the other relay.

I tried grounding the EEC test port, but still all you hear is the relay clicking, but no prime.
 






RobertFord

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1991 Ford Explorer XLT
Well, the son'bitc* rides again! The PO had installed some ghetto anti-theft device between the drivers seat and the arm rest. This switch had always worked, but decided to stop working just now. We had thought this switch would be positioned after the inertia switch, scheme wise, but the PO had decided to cut the wires under the passenger carpeting and insert the switch wiring there.

As the switch was broken, we were unable to measure any resistance on the wire from the relay to the inertia switch, which was the cause for looking at those wires and finding the problem.

Thanks for helping all!!
 






Roadrunner777

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Somehow, on my X, the three relays under the distribution box have different colors, but more importantly, different layouts of the pins (I looked ad swapping the AC and fuel pump relays) also there's a different indent on all connectors that prevent one plug from being inserted into the other relay.

I tried grounding the EEC test port, but still all you hear is the relay clicking, but no prime.

Yeah, my bad, I wasn't thinking you had a 91, the earlier 1st gens had a different fusebox.

Anyway, glad you got it running!
 






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