Hey everyone,

I posted yesterday about my fuel milage woes but had another discovery today.

I have a 92 f-150 with a 5.0 v8 with duel tanks.

I thought that I was getting terrible gas milage after having my truck sit for 2 weeks while on vacation. I was wrong I think.

I typically use the rear tank only as the front tanks fuel guage doesn't work. I generally keep $5-$10 of gas in the front and drive on it for a while every week or so just to keep it in use. I have been getting terrible gas milage for the last week or so, down from around 16 MPG to around 10 or so. Well, today I drove to work and got out and noticed that the front tank was spilling gas out of the cap after I turned the truck off. I took the gas cap off and the tank was completly maxed out to the point it was standing above the fill hole. I've come to the conclusion that somehow the gas is being transfered to the front tank somehow in transit to the engine from the rear tank.

Has anyone ever had this happen to them? I never fill the front tank so it must be coming from the rear.

I looked in my chiltons but it doesn't really trouble shoot anything like this and doesn't have any real details that I can kind of trouble shoot what is going on. Without trying to pry info from a dealer or something I'm just not sure where to start to even try to fix the problem.

If any one has any idea what is happening that would be great.

Thanks,

Kyle

 

The front pump is allowing fuel to enter from the rear tank. used to be an old recall that put anti-siphon valves on the outlet lines of the pumps. If you replace the front fuel pump, it should solve the problem. They won't pump from the front to the rear. Also, a new ford pump will have a new sending unit on it for the gauge.

Robbie

 

Thanks for the response.

Here is the kicker to that. I just started running the truck off the front tank and it runs fine and the fuel milage is back up to 16MPG.

Perhaps it is just the siphoning?