1990 Mustang GT Not starting fuel pump not running?

bigmike73

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Jan 11, 2010

#1

• Jan 11, 2010

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my 90 gt wouldn't start the other night when i was out so i got it towed home having this problem before it turns over fast but just doesn't start and doesn't start when i try to push start it. it acts like its going to start then kind of gurgles and doesn't. checked the relays and they are working and the fuel pump doesn't prime or anything. the inertia switch is getting power to it and coming out of it but the wire going down to the fuel pump is only getting about 5 volts. i put a jumper from the battery to the wire going to the fuel pump and it runs. this happened before and i got a new battery and that fixed it but it seems like the battery is fine it not more than a couple months old and i just put a new fuel pump relay and still nothing. Any advice would be great. and if you need more info just ask.

 

apollo12

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port st.lucie fla

Jan 11, 2010

#2

• Jan 11, 2010

• #2

I'd say double check all the grounds,did you ever replace the ign switch?

 

bigmike73

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yea i replaced the ignition switch a couple of months ago

 

apollo12

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port st.lucie fla

Jan 11, 2010

#4

• Jan 11, 2010

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Did you double check the emergency cut off switch in the rear of the car?

 

bigmike73

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yup seems like i have checked everything...

 

tannerc91gt

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Jan 11, 2010

#6

• Jan 11, 2010

• #6

Check the EEC relay. Im having the same issue. Relay is fine, Pump is fine, Inertia switch is fine. I can jump the pump and start the car, but pump wont prime when key is turned and wont run for very long when jumped. Im replacing the EEC relay in a few days

 

gungfusemaj

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Jan 11, 2010

#7

• Jan 11, 2010

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I dont know what the name of it is but its a relay under the Driver seat /green I think, I had one that would cut out on me all the time going down the road. chased it down for a week and no one could tell me what it was but when I replaced it, my fuel pump would then prime on initial turn of key. Worth a shot its a dollar at a junk yard Think I'm crazy, try it, your pump isn't working now. I had replaced my Ignition switch and harness and everything related because I thought that would be it, having a loose switch....

 

bigmike73

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Jan 11, 2010

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i already replaced the one under the seat but thanks anyway and tannerc91gt ill try that relay tomorrow is that the one under the mass air meter??

 

HISSIN50

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Jan 11, 2010

#9

• Jan 11, 2010

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What values do you see at the FP relay socket? One wire will have constant 12V. Yours might not, which indicates an issue with the wire or fusible link (it comes from the starter solenoid).

If one wire has constant 12V, turn the key on and note the values of the other wires during the prime-out.

 

bigmike73

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Jan 12, 2010

#10

• Jan 12, 2010

• #10

replaced the eec relay and i can hear the pump trying to prime but doesn't seem like it's getting enough "Juice"

 

HISSIN50

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Jan 12, 2010

#11

• Jan 12, 2010

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bigmike73 said:

replaced the eec relay and i can hear the pump trying to prime but doesn't seem like it's getting enough "Juice"

Click to expand...

What were the results of the FP relay socket testing?

 

bigmike73

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Jan 12, 2010

#12

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the pink wire has nothing except for the first 2 seconds when i have the key on and then it has 7.89 then when i have the key on the green wire has 11.60 the red/black wire has 11.56 the brown wire has 11.55

 

tannerc91gt

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#13

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the EEC relay is above the computer (kind of a hard to get to) http://www.allfordmustangs.com/foru...8236-eec-relay-location-ecm_eec_relay_loc.jpg

in terms of the fuel pump relay, Pink should have constant power with key on, red is going to be your 12v ign. source (primes the pump, which is what you arent hearing correct?), green goes through the inertia switch to the pump, and the light blue is a ground.

you should have 12v to the pink wire at all times, and if you jumper the pink wire to the green you should hear the pump prime, this should tell you if your pump is functioning.

 

bigmike73

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Jan 12, 2010

#14

• Jan 12, 2010

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yea im not hearing the prime of the pump and the pink wire is the one the relay shuts off after 2 seconds so idk

 

tannerc91gt

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are you testing the relay under the seat or the relay beside the MAF?

 

bigmike73

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under the seat

 

liljoe07

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Jan 13, 2010

#17

• Jan 13, 2010

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Posted via Mobile Device

I think you have a bad pump, you have the correct voltages in the right spots and the relay is working as it should. So the pump should be working. You may need to drop the tank, and make sure that the connector on the top of the tank is showing battery voltage with the key on and fuel pump trigger at the code test port grounded. If the voltages rises to normal, then the pump is faulty.

I answered most of your questions over at All Ford Mustangs, but I was under the impression that the pump was turning on. Like I said over there, usually low volts means there is a high amp draw(kinda like starting the car, the battery voltage drops because of the increase in amps). Which could mean that the windings in the pump are shot.

 

bigmike73

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Jan 13, 2010

#18

• Jan 13, 2010

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i'm hearing the pump prime but it isn't as loud as it is usually is. i wasn't hearing anything until i replaced the relay under the maf.

 

liljoe07

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Jan 13, 2010

#19

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Posted via Mobile Device

What's the fuel pressure at?

 

bigmike73

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Jan 13, 2010

#20

• Jan 13, 2010

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idk what the fuel pressure is but the pump just isn't priming