Hello,

I recently purchased a very nice 93 F150 XLT. The truck is in great condition except for one very pesky problem. It is a short wheelbase with dual tanks. The rear gauge works fine but the front guage always shows empty. A couple weeks after I purchased the truck I filled both tanks. The next day I have a large wet spot on my driveway directly under the front tank filler door and a constant drip of gas. I opened the door and took the cap off and about 2 ounces of gas poured out. I have put gas in the back tank a couple times since but nothing in the front. I have even tried siphoning gas from the front. Later, the same thing, gas dripping from the filler tube at the cap. Anyone seen this problem? Thanks for any advice.
Jim

 

You will need to replace both fuel pumps.
There are internal check valves in the pumps that are sticking.

 

i had an 89 with dual tanks. when i would use the back tank, the switch didnt close all the way, and some gas would get put into the front tank. if the front tank was full, then it would overflow. other wise, i would use the front tank til it was empty, then use the back tank, then use up what was left in the front tank (overflow from back tank) before i filled up again. from what i have heard, there was a tsb on it, but i never got it fixed.

 

I agree with the spaceman on this. The check valves are designed to hold pressure in the fuel system for start up. It sounds like the switching selinoid might be hanging up and allow rear tank fuel to bleed off into the front tank ( either through the fuel or vapor recovery lines.) Might be worth the bucks to change it out first or atleast check it to see if it is operating right.

 

Thanks to Home Skillet, Spaceman Spiff and Pestco1. I will try using only the rear tank and see the results since it appears the front tank guage does not work anyway. If that does not give some relief, I will try the solenoid and/or the fuel pumps.
Thanks,

 

In regards to the fuel pump check valves.
The return and pressure side is always closed, untill that pump is running.
This allows the fuel to return back to the tank that is selected.

If the valve on the return side is stuck open, the fuel will return to that tank.


The fuel pressure regulator is what keeps pressure in the fuel rail for engine start up.