I have a 96 f150 4.9ltre. truck has 251k and lately i have noticed that on the rear gas tank, If I fill the tank completely full, usualy only takes about 14-15 gallons (figure there is about 1gallon un-useable) I can only drive for 200 miles. but If I only put in 5 gallons can get 100 miles. Why is that? can someone help me on this issues. Is there a fuel tank pressure problem?

 

Is it leaking?

 

NO AND I DID THINK FOR A MIN THAT SOMEONE WAS STEALING IT FROM ME BUT THAT WASN'T THE CASE.

 

Sorry Guys I Don't Know How This Double Posted But It Did. Sorry About That.