Question about Ford Mustang
My car turns but the fuel pump doesnt stop pumping when I turn the key to run. I replaced the pcm a month ago and it worked jut fine until today. it is a 91 2.3L 4 cyl automatic. I think it has to be some ground which is giving troubles to the pcm...
Look for your ecu relay its above your mustangs ecu. Look behind the passengers side scuff plate. Its kinda tough to reach on the 87-93 5.0 Mustangs it may be easier on your 4 banger try to access it by releasing the glove box retainers by squeezing side of box once opened it should pop loose for you. Now look to the right there should be a Classic 80's style ford relay take this relay off replace it also check your fuel pump relay as it may be causing these issues. On my 87 5.0 the fuel pump relay is under the drivers side seat, yours might be in the same spot if not look for the relay located by maf in the engine bay. The relay looks identical to the ecu relay replace this also might as well since you're troubleshooting a car over 20 years old...... I think you can get them for 5-10 bucks at any auto parts place. hope this helps you or another person with the same issue on their stang. Look at picture for what these relays should look like I circled it for you.
Posted on Feb 04, 2015
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Posted on Jan 02, 2017
If you replaced the fuel pump then there is a possibility that during the job then some debris from the tank and/or filter got loose somewhere into the fuel system and is in your lines. It could even be a very tiny speck of gasket material, old or new.
Posted on Jun 20, 2009
If you don't think your getting the ground command through your PCM, you can make your own ground just by bypassing the PCM all together. First you need to find a PCM connector end view showing which pins are which wires and locate the ground you need for that circuit. Then you need enough wire to loosely run from your battery negative terminal to the PCM connector. I you can back probe the PCM ground wire with a sewing needle and wrap the new wire around it, and attach the other end to the batt. neg. your just allowing the PCM to get it's ground another way. If it still doesn't start, try swapping fuel pump relays w/ a head light relay or one w/ the same part number on it. If you can't find one, just hot wire the pump relay again just to see if it starts and runs. If it does start and run you'll need to go to a wrecking yard and pick up a used PCM and maybe buy a relay for the fuel pump. I sincerely hope this info helps in some way.
Posted on Aug 07, 2009
It won't hurt to jump sire to drive, It is designed to pump all time when the engine is running. The only problem is the pump should not be on if engine is not running since it is designed that way to prevent a fire while pump continues on once engine is stops in a car accident. There is a control device to immobilize the fuel pump, if there is no speed sensor signal from the crankshaft. This needs to be located and fixed.
Posted on Oct 14, 2009
This sounds like the PCM has taken a turn for the worst. The pcm relay sends power to the fuel relay for 2 seconds to prime the fuel system just before start up.
Then the pcm ungrouds the signal for a prove out.
Posted on Oct 23, 2009
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