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WTF is wrong with this thing?! Fuel pump/relay related

  • Thread starter Thread starter mustangphil
  • Start date Start date Apr 26, 2010

mustangphil

Founding Member
Jul 9, 2002
21
0
48
No longer The Beach
Apr 26, 2010
#1
  • Apr 26, 2010
  • #1
I was doing about 20-30 mph and the car just died. Right away I listened to see if the fuel pump is priming, nothing. I got the car home couple of days later and now it's in the driveway with me pulling my hair out.

I searched to see what the problem could be and read that I can trick the pump into running by jumping one of the EEC connectors to the ground. Turn the key and BAM! Fuel pump is running, the car started and runs.

I disconnected the jumper, turn the key on and the pump is continuously running. As soon as I try to start it the pump shuts off. With the key in the on position the pump kicks back on and keeps running and again shuts off when I try to start the car. Or, it doesn't run but when I tap the relay with my finger, the pump turns on again.

I replaced the relay with a new one and it doesn't do anything, even if I tap on it (it also has one more prong then the stock one). Is it possible that they sold me a wrong or faulty relay?

Last, I tried to pull the codes (I have the code reader) and it doesn't dump any codes into it. It indicates that it's connected with the car, it also indicates when it finds a code but doesn't display any and acts as if it was frozen. I can't hear any clicking as I did before when I scanned it months ago.

So I turn to you Mustang Gurus for help. Thanks in advance, Phil

EDIT:

I got the car to start and let it run for about 15 minutes to reach normal operating temp. When I shut it off and turned ignition back on the fuel pump primed for about 2 seconds and shut off. The I started the car with no problems. Shut it off and tried to pull the codes again.

Here are the results:

31 - EVP or PFE circuit below minimum voltage
87 - Fuel primary circuit fault - Red flag perhaps?
95 - Fuel pump secondary circuit fault - red flag again?
96 - Fuel pump secondary circuit fault / high speed fuel pump relay open

With that said, all of those codes existed when I first scanned it back in December but didn't do anything about it because of lack of time and the car ran fine. I know, I know, just putting it off, shame on me. So what would fix the problem, should new relay do the trick?
 

HISSIN50

"How long does it take to get help in here?
15 Year Member
Nov 29, 1999
31,179
34
129
Apr 27, 2010
#2
  • Apr 27, 2010
  • #2
I might try wiggle testing the relay socket to see if you can make the car cut on and off (while it's running).

The extra relay terminal is probably no biggie. The stock relay is an SPST, but a SPDT (which has an extra prong for a normally-closed circuit, which simply is not used for a FP circuit) is probably what you got. Should be no biggie.

If your WOT relay looks ok (they get fried from heat), it should be the same relay as your FP relay.

Good luck.
 

mustangphil

Founding Member
Jul 9, 2002
21
0
48
No longer The Beach
Apr 29, 2010
#3
  • Apr 29, 2010
  • #3
I replaced the FP relay and, reset the EEC, and the codes went away except for 31. So I guess the relay fixed the problem.
 
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