I have an 85' f250 4x4 460 4sd. I have changed the carb out, changed the fuel tank selector valve, changed the front tank and fuel pump, chaged fuel lines, changed the vapor seperator, fuel pump relay, oil presure switch. I have changed all this stuff over the past two years. I'm getting to the last resort with her. I can start the truck it will run for about 2-3 mins. and then shuts down. When i try to give it some gas it sounds like its starving for gas. Its getting spark the whole time its shutting off. It will restart after this happens with same results. Is there any thing else that might be shutting off the fuel or pump or both or anything else.
Or i have a new rear tank and do a out of tank fuel pump and direct line to the carb with a bypass presure regulator. I just don't have the time to do this swap yet. I need to get the pipes out of the way first. Any help would be greatly aperciated.

 

Go over to the starter relay and see if you can find the darkblue wire that goes to the fusible link, and then runs into a pink/black. If you can find this wire, disconnect it from the starter relay and hook it to the battery +, and see if it will run this way. This should hot wire the pump you have selected and make it run all the time.

 

will it turn off when i turn thr truck off?

 

If you directly connect it to the battery, then no, it will not turn off when the truck is shut off.