T_Auto

When we ground it, it goes to full. It's the second pump we put in so we were having a hard time believing it would be the sender. The gauge works if we turn the key on but when we start it the gauge stops working for the rear tank.

I did not. I will look at that. Thanks so much!

Hi all! I don't own a truck but work at an automotive repair shop and these forums can be helpful at times. We have been working on an 86 Ford F250 and have been having trouble with the fuel gauges working. I decided to join because I saw where a poster had been having problems finding the correct fuel pump assembly for the rear tank. We had this same problem and was beating our heads against the wall. The local parts house got us a fuel pump assembly that looked similar but the gauge would read opposite. We found out the assembly the parts house got us came out of an 87 which Ford changed the wiring. We just thought the sending unit was defective. After looking at wiring schematics we noticed the 86 5.0l and 7.5l fuel systems were almost identical. I looked at the 86 F250 5.0 fuel pump assembly and bam, it was the correct one. The way I found this group is because the customer came back complaining the fuel gauge isn't working. So, I have been checking out forums to see if others have ran into these problems.

We recently fought this same problem at our automotive repair shop. After looking over the wiring schematics and seeing that the 7.5 and 5.0 fuel system was wired almost identical led me to look up what a rear fuel pump for an 86 Ford F250 with a 5.0 looked like. And it was the one we needed! The Carquest part number was HS3496087.