I have recently replaced the front fuel tank and pump in my duel tank truck. 1994 f150,5.8 The question I have is that i have been told that i need to somehow block off the rear tank since I am going to run on just the front tank for the next 6 months or so. The reason i have changed the tank and along with several other things, pump, filter, injectors, is that the truck had been stored for the past 8 yrs. So I know that the fuel turned to varnish. Will it be ok to run it this way or do i need to block off the back tank and if so whats the best way of doing it? thanks for any help.

 

If you're not using the rear tank, the pump module in it will operate as a (dual) check valve for both the pressure and return lines. As long as you leave the tank and sending unit in place (and the check valves are sealing) it won't affect the truck.
Worst case, if one of the check valves were not working you would get cross filling (pumping gas into the rear tank), but don't worry about crossing that bridge if it's not an issue.

 

Thanks Chris, I was thinking about taking out the rear tank tomorrow and using some hose and clamps to seal off the tank from the fuel system, but now I can use my time in figuring out some other problems im having.