Hey guys just bought a '90 f150 with duel tanks but only the front tank works. The fuel gauge reads empty on the front tank and full on the rear, any ideas what my problem could be. I'm not new to working on trucks just these trucks!

 

What do you mean only the front tank works? The fuel pump could be bad or the connection is open. As for the quantity indicator, it's either a stuck probe or again a bad/missing connection. I'm not sure, but I think the pump is internal along with the quantity indicator (for obvious reasons). This means dropping the tanks and splitting them.

Before all that PITA work, check to make sure there's fuel in the rear tank. You could even try draining (not sure if possible) both tanks and filling them back up slowly to make sure the indicator is reading correctly. Had a friend with a '89 F-150 that had an inaccurate indicator and it caused him all sorts of problems.

 

Sorry that wasnt very clear, I was in a hurry when I posted it. The rear tank hasnt had fuel in it in over ten years and when you knock on it you can hear the rust rattling so I know its empty. With it reading full something is obviously wrong. The front always reads empty no matter what.

 

You've got some electrical issues then. And that tank should probably come out and be split anyways if there's rust in it.

 

Thanks for that. Kinda what I already figured and I know I have to replace the tank already got.one on the way.

 

I had a gas gauge issue with my 2003 Explorer. It would always read 1/4 tank. I was told by the dealer just to disconnect the battery for like 10-15 mins and it should reset. I tried that and it did the trick. Not sure if it will work for you though but might be worth a try.

 

Mine did that, the fuel float was corroded inside the tank. Also the fuel tank selector was running hot and malfunctioning. I took the tanks out, replaced the side tank and ran new line to engine.