Hello James, My name is Colton, I live in Denver Colorado. I am going to high school and taking an auto class. So I’m very familiar with cars. I have had this problem with my truck ever since I got it. I have a semi-hot rodded 1986 Ford F-150. The only thing special about it is that it has a 302 1991 Ford Mustang EFI motor that was designed to drag race, it has true dual exhaust with 36 inch glass packs. The original engine for the truck was a 302 EFI system so not much of a difference. My problem is that I have two gas tanks, one is 16 gallons and the other is 25 gallons. I have been running off of the 16g tank ever since I got it which was a year and a half ago. Every time I throw the switch to start running of the rear 25g tank, it only runs for a couple min and then dies out as if it ran out of gas. I know it’s full because I filled it when I first got it and I put some gas in it to see if it was leaking but it would only let me put half a gallon in it so I know it’s still full. I have been told three things on what to do. I should go and replace the switch with a three way toggle or two switches, one for the 16g and the other for the 25g tank. Or the fuel pump is bad in the rear tank and needs to be replaced. And third, buy a separate fuel pump to pump gas from the rear tank to the front tank. I would really appreciate it if you e-mail me back soon so I can fix this once and for all because I’m tired of it not working right.
Let us start with the premise that you are not getting fuel from the rear tank. First thing I would do is verify that power is getting to the rear tank fuel pump. In order to do this you will need to find the wiring schematic for this vehicle. The problem is that it is very difficult to get to the wiring on the rear fuel tank so here is a suggestion. Remove the 6 bolts that hold the truck bed on the frame and the 6 small screws that hold the gas necks to the bed. Have you and your buddies pick up the truck bed and remove it from the truck. Now you have access to everything you need to test. Now you can test the fuel pumps and sending units as well as the switching valve. From my experience it is always the fuel pump. Please don’t change the way the truck is designed to work from the factory. The 1986 trucks use a low pressure pump in the tank to supply fuel to the high pressure pump on the frame.
Live long and prosper in 2011.
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