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Electrical No start sometimes…..fuel pump not priming unless I tap FP relay

  • Thread starter Thread starter JimProfit
  • Start date Start date Apr 17, 2022

JimProfit

Member
Apr 4, 2022
12
2
13
Jersey Village, TX
Apr 17, 2022
#1
  • Apr 17, 2022
  • #1
I bought this 1993 GT Convertible with 93K miles a couple weeks ago. It wouldn’t start so I followed the troubleshooting list. It would crank, but not fire. The FP would not stop priming. Long story short, I replaced the EEC relay and it was fixed. Now 2 weeks later it won’t start again. This time the FP won’t prime. If I tap the FP relay the FP primes continuously, but no start. I started going through the checks and randomly it decides to start just fine. WTH? I really hate getting stranded so I‘m considering replacing the FP replay with OEM part, new FP and maybe even send my ECM out for refurbishment just in case. Waste of money, maybe. Any thoughts as to why no FP prime and then an hour later it primes and starts? Maybe the pump is going bad? Grounds look okay….no major rust anywhere.
 

JimProfit

Member
Apr 4, 2022
12
2
13
Jersey Village, TX
Apr 18, 2022
#2
  • Apr 18, 2022
  • #2
Well, back to cranking and no start. It ran fine this morning.
 

General karthief

wonder how much it would cost to ship you a pair
20+ Year Stangneter
Aug 25, 2016
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polk county florida
Apr 18, 2022
#3
  • Apr 18, 2022
  • #3

Cranks OK, but No Start Checklist for Fuel Injected Mustangs

Cranks OK, but No Start Checklist for Fuel Injected 5.0 Mustangs model years 1986-1995 A word about this checklist before you start: it is arranged in a specific order to put the most likely failure items first. That will save you time, energy and money. Start at the top of the list and work...
www.stangnet.com
 
Reactions: JimProfit

JimProfit

Member
Apr 4, 2022
12
2
13
Jersey Village, TX
Apr 19, 2022
#4
  • Apr 19, 2022
  • #4
The FPR wires tested okay as well as the inertia switch and FP in the trunk. It won’t go into self test mode nor does my ODB reader work. Just reads 0. I believe that the test mode is controlled by the PCM so I’m thinking that’s my issue. I pulled the PCM and it has some green fuzz and one of the caps is sticky and looks corroded at the base. Time to pack it up and ship it off to one of the eBay PCM fixers. $110 is totally worth it if it solves my problem.
 
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