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EFI starting issue

allenfahey

Bronco Guru
Joined
Mar 18, 2004
Messages
2,672
I have 93 Mustang EFI on my Bronco. Has ran great for the most part for years. I went to take the Bronco out and it died in the driveway.
I have a fully charged battery and it cranks over great but doesn't fire.

When I turn the key to the 'on' position it only sometimes turns on the relays. and when it does they are sometimes weak. Other times nothing, no relays click or are weak. I got a couple brand new relays and tried them but it's the same. I also checked the wiring on the frame rail mounted fuel pump which is a 86 fuel pump. As suspected, there isn't any power coming to it which I suspect is because the relay isn't turning on when the key is turned to the 'on' position. I have always heard the relay(s) click then the fuel pump cycle on before starting.
I replaced the relay under the dash near the computer and still nothing.
At least it died at home and not on the trail ruining a wheeling trip but I'm at a loss as to what it can be. HELP!!!
 

jim3326

Bronco Guru
Joined
Jul 12, 2010
Messages
1,781
Loc.
Appleturkey
I had the same issue, changed out the ECU and same thing. I ended up bypassing the fuel relay and put in a toggle switch and have been running that way since ~5 yrs.
 
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