I have a 1990 F250, inline 6 cylinder. I am having problems with the rear fuel tank. When I flip the fuel selector switch from the front to the rear the truck will starve of fuel and die. I just installed a new fuel pump in the rear tank, thinking that this was the problem, but It wasn't. Fuel pump is getting power because I can hear it kick in, and also the old fuel pump would kick in, but I thought it might have been just going bad. There is no selector valve on the frame of this truck. Just the lines coming up from the rear tank and teeing into the front tank and going into the fuel filter. I have just about give up I dont know now what to check. Any one with some ideas. I dont think the selector switch is bad, fuel guages read accurately on both tanks. Just as soon as I flip the switch to go to the rear tank the truck will run on what fuel is left in the line from the front tank pumping. Any ideas. thanks

 

Late model trucks have an in-tank Fuel Delivery Module in each tank. If you have a Haynes Manual look at page 4 - 12.

Tank selection is determined by which in-tank FDM is energized by the dash mounted switch. You say the rear pump/FDM does get power. Okay that's good.

The gas in both tanks good? Ever been bad? Could there be any blockage in the rear line (before or at that tee) messing up fuel pressure? Notice any leaks anywhere? Had any problems with fuel return, like returning to the wrong tank and overfilling it etc?

 

Yes gas is good in both tanks, I am thinking the same thing maybe about a blockage in the line at the tee. Every thing in the tank looked very clean, that sorta made me think that might not be the problem. There isnt any leaks anywhere. Havent been any problems with the fuel returns. I will try to seprate the lines at the tee and check it to see if it might be stopped up. If it isnt I dont really know what else to try.

 

Hey, if I can't tell you what else to try someone else can, but you definitely won't figure it out by giving up. The feeling of finally figuring it out will be awesome, I know mine will haha. Can't wait to start the truck again, I just HOPE it runs right.