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Fuel Fuel pump does not prime

  • Thread starter Thread starter justadude07
  • Start date Start date May 26, 2025
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    fuel pump circuit
J

justadude07

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#1
  • May 26, 2025
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So I have a 1986 mustang gt 5.0 HO and the fuel pump stopped turning on. I replaced the relay under the seat but still no go. Im just wondering what else I should check. I saw some people say inertia switch but it is not tripped in my car. I dont know im just trying to get this figured out.
 

AeroCoupe

lube between the nut and the face. I know my lubes
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May 26, 2025
#2
  • May 26, 2025
  • #2
Have you pulled codes?
 

gkomo

now i can hopefully expect to receive the shaft
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#3
  • May 26, 2025
  • #3
Have you checked the plug on top of the tank? Maybe it came loose?
 

91AOD5.0LX

I have a slight sag in my rear
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#4
  • May 26, 2025
  • #4
@jrichker is still helping us all and will always continue to do so.
Give his post a read…. Lots of great information regarding your problem:

Post in thread 'fuel pump cicuit help 86 gt 5.0 please?'

Jul 13, 2009
Fuel Pump Troubleshooting for 86 Mustangs

Clue – listen for the fuel pump to prime when you first turn the ignition switch on.
It should run for 2-5 seconds and shut off. This on and off again cycle helps to prevent
flooding the engine when cranking. To trick the fuel pump into running, find the ECC
test connector and jump the connector in the upper RH corner to ground.






If the fuse...
  • jrichker
 

nickyb

I gotta say i never painted my nuts, Never Ever
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May 26, 2025
#5
  • May 26, 2025
  • #5
Sometimes that inertia switch needs a good swift kick in the ass to reset. Try it its free.
 

KRUISR

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Apr 16, 2015
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#6
  • May 26, 2025
  • #6
On my '90 I found the fuel pump circuit runs through a connector in the driver side kick panel. The female pins in that connector had loosened up and would intermittently shut down the pump. I used a small screw driver to bend the ends of the female tabs more closed - to make a more solid connection when the connector is reconnected. It has worked great since - going on 3+ years now.

I actually had my power windows acting up similarly and did the same thing at the driver side power window switch - worked perfect ever since.
 
J

justadude07

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#7
  • May 26, 2025
  • #7
AeroCoupe said:
Have you pulled codes?
Click to expand...
I haven't. Car is torn apart right now. I was getting ready to drive it onto a trailer to get it painted but it decided it didnt want to start.
 
J

justadude07

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#8
  • May 26, 2025
  • #8
gkomo said:
Have you checked the plug on top of the tank? Maybe it came loose?
Click to expand...
Haven't yet. I was trying to avoid dropping the tank but I'll probably have to
 
J

justadude07

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May 26, 2025
#9
  • May 26, 2025
  • #9
91AOD5.0LX said:
@jrichker is still helping us all and will always continue to do so.
Give his post a read…. Lots of great information regarding your problem:

Post in thread 'fuel pump cicuit help 86 gt 5.0 please?'

Jul 13, 2009
Fuel Pump Troubleshooting for 86 Mustangs

Clue – listen for the fuel pump to prime when you first turn the ignition switch on.
It should run for 2-5 seconds and shut off. This on and off again cycle helps to prevent
flooding the engine when cranking. To trick the fuel pump into running, find the ECC
test connector and jump the connector in the upper RH corner to ground.






If the fuse...
  • jrichker
Click to expand...
Will do!
 
J

justadude07

New Member
May 12, 2025
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May 26, 2025
#10
  • May 26, 2025
  • #10
nickyb said:
Sometimes that inertia switch needs a good swift kick in the ass to reset. Try it its free.
Click to expand...
Figured. I'll get give it some love lol
 
J

justadude07

New Member
May 12, 2025
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May 26, 2025
#11
  • May 26, 2025
  • #11
KRUISR said:
On my '90 I found the fuel pump circuit runs through a connector in the driver side kick panel. The female pins in that connector had loosened up and would intermittently shut down the pump. I used a small screw driver to bend the ends of the female tabs more closed - to make a more solid connection when the connector is reconnected. It has worked great since - going on 3+ years now.

I actually had my power windows acting up similarly and did the same thing at the driver side power window switch - worked perfect ever since.
Click to expand...
Alright I'll give it a shot
 
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