Relay MYSTERY??????

[Trickedoutstang]

I have been trying fix an eletrical problem but cant seem to find the culprit. THe problem is that I have two relays one oem from ford and the other GP sorensen from discount. What's happening is that my fuel pump depending one which relays I use either makes the pump keep priming until I turn to OFF or doesn't prime at all. Here's what I have done so far:


- REplace FP relay under seat and behind ECM with discount auto = no prime

- Use OEM ford relay under seat and discount auto relay behind ECM= Wont stop Priming ( reverse them and = no prime)

- Replace fuel pump with new 190lph edelbrock.

- Checked all grounds and inertia switch

- Brand new battery

- tried running codes with scanner but never got anything but a solid light

- have 12 volts at pin 22

- checked FP relay lt. blue/orange wire with ecm disconnected for 10k+ ohms and got nothing which would lead me to believe its a short from the relay to the pump
according to the forums but I am not sure.

I either think it's a fubar ECM or a short but would like to know why the relays are doing that and also If there is a way to check if the ECM is good, before I buy one. I am kinda new to the electrical stuff but have done extensive searches on corral, stangnet and *******.com and have all the diagrams but I am still guessing. Any help apreciated.

 

[FSTNG]

sounds like a toasted ECU to me, or a corrupted tune if you have a tuning device. You can get a used box off of eBay or go to the auto parts store to get a remanufactured unit. The only test I can think of is to pull the EEC and apply B+ and GND to the appropriate pins while monitoring the fuel pump output voltage to take everything else out of the loop... but it sounds like you have replaced/checked everything that could cause a problem, so my guess is a bad EEC unit since the running fuel pump circuit is a common tell.

 

[Trickedoutstang]

Yeah It prob is the ecu but i wish there was a way to check it, i'm on a college students budget so every dollar counts