Dual fuel tank siphoning issue

ICECREAM BOB

MEMBER
FORD F-150

1989 ford e 150 5.0L
the selector switch for the tanks does not work, leaving only the back tank to use. Fuel pump in front tank is no good.
we replaced the fuel pump in the back tank and repaired a hole in it, have also replaced both fuel filters and the inline fuel pump.
keep putting gas in and seems like it was loosing it all, until we took off the front tank gas cap and gas came pooring out.
Seems that the front tank is siphoning out the gas from the back tank
How do I fix this as this van has been made into ice cream truck and is a source of income. Must keep it rolling. PLEASE HELP! :Mrgreen:

1 Reply

BLACKOP555

MECHANIC
10,371 POSTS

Thats the defective year. Your problem is a faulty dual fuel tank selector valve it is located underneith the truck on the fuel rail there should be four lines going to it and two coming out. The four lines in consist of the front and rear fuel tank. This part is not made anymore at part stores so you may have to check with the ford garage to see if you may get one or go to a junk yard and find one, which may be faulty also.

They are about 80 bucks new I dont know with a junk yard I just bought two of the fuel lines and put a splice in it and bypassed the front tank as there is a hole in it and I never use it.