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1987 - 1996 F150 & Larger F-Series Trucks 1987 - 1996 Ford F-150, F-250, F-350 and larger pickups - including the 1997 heavy-duty F250/F350+ trucks

91 fuel pump issue

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Old Aug 1, 2019 | 05:37 PM
  #1  
daleftman's Avatar
daleftman
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From: Jones, Oklahoma
91 fuel pump issue

i have a 1991 f150 302 i got from my grandfather the truck bed was dented beyond repair so i got a used bed and while i was there i picked up a rear tank and rear fuel pump (looked brand new) of that same truck which happened to be a 89 reason being the rear tank on mine had 15 year old gas in it so i figured i might as well. so i installed the tank with the pump in it and after i did so and ran into some problems. first off the truck will not start and the front fuel pump sounds like its pumping and when i go to the fuel rail and push on the bleeder nothing happens but when i go to the rear tank fuel is pumping into it but there is a problem i don't have a pump on it i made a cap just to seal it off for the time being. the fuel pumps are different between a 91 and a 89 so all the fuel is dumping into the rear tank i did some wiring hoping that would work but nothing. is there anyway i could prevent the fuel from going into the rear tank?

pump from a 89

pump from my 91

(female end off of 89 pump just showing that there are 2 female ends)

i had to rewire it because the 89 has a female end the 91 has a male end. The 89 wires consist of -red and black--yellow--black--grey and red-. The 91 wires consist of -yellow--orange--grey and white--black- and i wired it based on picture 5 and 6 the wires that lined up inside the connector i wired together

(picture 5)

(picture 6)
 
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Old Aug 2, 2019 | 09:25 AM
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1989 had a different pump system than 1991. In 1989, the trucks had a low-pressure pump in the tank and a high-pressure pump (that services both tanks) on the frame. Your 1991 would have had an ITR (in tank reservoir) unit which places the high-pressure pump in the tank.

I can see from your last pic that pump laying on the ground is a low-pressure pump for a 2-pump system. That will not work on your 1991 unless you also put one in your front tank and a high-pressure pump on the frame rail.

I recommend you get a proper ITR pump for your rear tank and put the wiring back the way it was.
 
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Old Aug 2, 2019 | 10:47 AM
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From: Easton,Ks
Where did you get the second photo?
It looks like a 1994 or newer pump assy.
 
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Old Aug 2, 2019 | 01:05 PM
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The 2nd pic if of an aftermarket pump - that is not a Ford connector like the 1st photo.
 
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Old Aug 2, 2019 | 05:56 PM
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Two threads. Same question.

https://www.ford-trucks.com/forums/1...-gas-tank.html
 
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