i have a 86 f150 ext cab laiat xlt short box with dual tanks (its efi) front tank with out my knowlde filled to the point it was over flowing but when i put on front tank pump would cut out after 5-10 min. then got a clod spell here siphoned 10 gallons out and now been driving a week on front tank with no issues anyone explain

 

you nay have had too much gas in it and the fuel pump probally couldn't return the unused gas back to the tank and it flooded out

 

but did why front tank fill fill itself

 

is your gas gauge working? I had that happen in a dodge once. but then again dodges are junk... sometimes, your gauge won't recodnize the fuel being in the tank..... mine does the same thing all the time,but when the gauge hits 1/4 tank.... that generaly means im empty.

 

front tank was ran near empty then one day decided to fill both tanks and took a gas bath on front tank. (thought might be gauge cause every so often i would accidently get switched to front and always seemed to move up first 1/4 then 1/2 ect). so tried running it but did as i said would cut out & die. swith tanks prime the key a few times off we go. but after siphoning that tank works fine someone told me that the return line wasnt switching between tanks and thats how the front got full is it possible?