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Discussion Starter · #1 ·
New to the forum. I am in need of some help with my 90 mustang. The fuel pump quit priming on me. I have gone through the checklist of things to do. I am only getting 5 volts to the inertia switch as well as fuel injectors. Car was fine one day and quit the next. I have seen other people on here with the same question but never really an answer to how they fixed the issue??? If anyone knows any info please help me out. Thanks for any help any of you can give. It is greatly appreciated.
 

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Have you checked the all your relays? Could be something stupid like that.


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On the '90, exciter power is run through the inertia to the FP relay. At the FP relay you should have a ORG/LT BLU wire that will be "HOT" from the fuse link at the starter relay (brown). If it is 12v. at the relay the circuit is good. With key ON, power to the FP relay via the inertia closes the FP relay, and the PINK/BLK wire at the relay becomes "live" and power will go to the pump. The 5v. you see at the inertia will most likely be the trigger wire to the FP relay. You should have the 5v. reference to each side of the inertia, or it's bad/tripped.

To "live" test the pump, all you need to do is make simple short jumper wire and put it between the ORG/LT BLU and PINK/BLK wires on the plug and the pump should run, provided you have the 12v. at the ORG/LT BLU. If that's good and still nothing, the pump may be shot. This is directly to the pump by-passing the relay.
 

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Discussion Starter · #4 ·
On the '90, exciter power is run through the inertia to the FP relay. At the FP relay you should have a ORG/LT BLU wire that will be "HOT" from the fuse link at the starter relay (brown). If it is 12v. at the relay the circuit is good. With key ON, power to the FP relay via the inertia closes the FP relay, and the PINK/BLK wire at the relay becomes "live" and power will go to the pump. The 5v. you see at the inertia will most likely be the trigger wire to the FP relay. You should have the 5v. reference to each side of the inertia, or it's bad/tripped.

To "live" test the pump, all you need to do is make simple short jumper wire and put it between the ORG/LT BLU and PINK/BLK wires on the plug and the pump should run, provided you have the 12v. at the ORG/LT BLU. If that's good and still nothing, the pump may be shot. This is directly to the pump by-passing the relay.
Ok thanks for all you guys help and info. I will be working on it this weekend.
 

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Discussion Starter · #5 ·
On the '90, exciter power is run through the inertia to the FP relay. At the FP relay you should have a ORG/LT BLU wire that will be "HOT" from the fuse link at the starter relay (brown). If it is 12v. at the relay the circuit is good. With key ON, power to the FP relay via the inertia closes the FP relay, and the PINK/BLK wire at the relay becomes "live" and power will go to the pump. The 5v. you see at the inertia will most likely be the trigger wire to the FP relay. You should have the 5v. reference to each side of the inertia, or it's bad/tripped.


Update: got the fuel pump fixed. It was the eec relay. Full of rust and corrosion. New problem. Im only getting 20lbs of fuel pressure at the rail on my gauge??? Any ideas why this is happening? It has a 255 walbro pump in it that i put in and the car got tuned and has been sitting for about a year after being tuned. Work and family has put a hold on wrenching. I am now able to start working on it again. I do have an adjustable regulator and it doesn't seem to change when i turn it in or out?? Any help is greatly appreciated. Also my fuel level gauge doesn't work. Could there be something wrong in the tank thats causing no gauge and low pressure? Thanks again for any advice given.
 

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Is this a stock rail? Are you reading pressure from the schrader port? That pump (if all is good) should be able to push 60psi in the line. You can deadhead it to a gauge and see if all's good. If not, start checking lines. Also, make sure you have enough fuel in the tank. If it's low, you'll lose PSI. You need to check all your connections to the pump and fuel gauge, which are separate. The system has a "slosh module" usually in the dash for the gauge to read steady due to sloshing fuel, but I'd check wiring first.
 

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Discussion Starter · #7 ·
Yes it is a stock rail, and yes i have a pressure gauge on the Schrader valve. Its a kirban fuel regulator. I thought maybe the diaphram went out but its not leaking fuel into the vaccuum line so idk how to know if there is anything wrong with it?? I am not sure how much fuel is in there since the gauge isnt working. First thing im going to start with is dumping fuel in it then ill go from there. I will reply with updates this weekend. Thanks so much for responding and helping me out. I really appreciate it.
 

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New to the forum. I am in need of some help with my 90 mustang. The fuel pump quit priming on me. I have gone through the checklist of things to do. I am only getting 5 volts to the inertia switch as well as fuel injectors. Car was fine one day and quit the next. I have seen other people on here with the same question but never really an answer to how they fixed the issue??? If anyone knows any info please help me out. Thanks for any help any of you can give. It is greatly appreciated.
192.168.100.1 192.168.1.1
A professional help might be needed in these situations , take it to a trusted garage and check it out
 
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