I just bought a 93 f150 auto long bed with 4.9l inline 6 cylinder 53,000 original miles with camper shell. filled up the tank drove 90 miles all highway and interstate and took 8.5 gallons to refill. that calculates to 10.6 mpg. according to the research i have been doing i should get about 18mpg hwy. anyone know what my problem maybe?

 

This forum is great. after much research i think i have found the problem. fuel from my rear tank is bleeding into my front tank. my front tank was empty when i filled the rear tank. now i have almost 1/4 tank in the front. guess i have a bad check valve.

 

There was a recall years back on those trucks with the 2 tanks. The valve between the tanks would fail.