I have a 93 f150 with a 4.9 I have been having problems with
the front fuel tank and after researching in a Haynes repair manual I have
found what seems to be the exact problem, The front tank may have a leak in the Fuel Delivery Modual it leaks fuel from the back tank into the front tank
and overfills the tank . Also when I switch to the front tank the truck
stutters and skipps like its starving for fuel but when I switch back to
the back tank it runs fine other than after turning off the truck the fuel
backs up into the front tank and you have to open the front tank cap and
releave the pressure. I have called a few local auto parts stores and no
one seems to know this part by what Haynes manual calls a Fuel Delivery
Modual (shuttle selector valve) any help with this would be appriciated,
Is it all part of the fuel pump or something different. And how hard would this be to change?

 

Just did mine two weeks ago. I think the 93 has the same setup as the 90. The Fuel Delivery Module is the in tank fuel pump, float and gauge sender all wired up and hooked up to the pipes that the fuel lines hook up to. That Assy sells for $180 - $250.

All you really need is the pump, it has an internal check valve on the fuel return line side that is only supposed to be open when you pump is on ... that part is not working and allowing fuel to return to the front tank when you use the rear tank ... sometime some fuel still returns to the rear tank. On mine the front pump would not work when it was full .. maybe over full ... probably some kind of short in the pump when it was full ... when I siphoned about 5 gallons out it would work. You are probably also spilling fuel on the ground when the tank overfills the fuel is pushed out of the vapor valve and into the charcoal filter by the battery, you probalby have a fuel smell there ... stronger than should be.

Try siphoning the level of the front tank down and see if it will run from it ... easier than siphoning all 16 - 19 gallons out like I had to when the pump finally failed. You will have to drop the tank and change the Assy or at least the pump, you will need a special tool to disconnect the fuel lines ... about a $10 tool, it should work on your fuel filter also ... which should probably be changed also. I found the pump for mine on eBay new for a super great price (about 1/4 what I quoted above, PM me for sellers name and details). I haven't used it much yet, just some idling in the driveway, but at least it is keeping the backflow from happening for 200 miles on the rear.

 

Thank you. Will try that first I guess!!

 

Let us know what you find.