no power to fuel pump

[LordMustangGT]

hey got a ? for you guys, my car is just sitting in my shop, I had it running yesterday, started right up no problems, today it doesn't work. I checked the fuel pupm relay, it's not clicking. The EEC relay is clicking, thats the one that sends power to the fuel pump relay right. So I checked power at the fuel pump relay plug, one always has 12v, another only 3v and the other two are dead. Now the one with 3v goes one and off with the key. should that have 12v. Any help would be great, thanks

Matt

 

[Black1987Stang]

I dont no about the 3volts, did u check the inertia switch anyway in the trunk? Im guessing you dont hear the pump come prime when u turn the key on run? If u got a buddy u can have someone prime the key or you can ground the bottom right spot of the code reader plug which will turn the pump on continously and unplug the connector right behind the rear bumper (fuel pump connector) by the gas tank and look for 12V there. Thats all i could think of

 

[HISSIN50]

I am with 87. If all you have at the FP relay is constant power and 3 volts on the other terminal, that 3 volts is the power from the EEC relay. And that power goes through the inertia switch, so if the switch is bad, that causes issues. Some folks use a jumper wire across the inertia switch (FOR TESTING ONLY) to see if that fixes the issue. Your meter can show how many volts are going in and coming out of the switch, which is revealing.

Did you check the ground wire from the puter to the FP relay with your meter (checking for volts obviously would not show anything, which is why I ask). That wire should show ground during the period that the pump primes, but then it will be gone, so test quickly.

Good luck.

 

[FastDriver]

check the inertia switch, and then try replacing the relay... if that doesn't get it, then it's the pump or a short. (you can always take the relay back to the auto parts store).

chris

 

[LordMustangGT]

thanks for the help, came out to be the main power wire to the ECM. I was tighting up the wire aroung the cilinod and had them all off, and when i put them back on I couldn't see it and forgot to put it back on. Started right up. Thanks for all your input.

Matt

 

[HISSIN50]

FWIW, when you tested it, that connection must have been working since it is the only wire to send constant 12 volts to the FP relay.

I only posted so that future searchers are not thrown-off based on symptoms vs the fix.

Glad to hear you got it whipped.