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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)
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.
