wayner - i had a VERY similar issue when i was filling my tank - turned out to be the filler neck for the jimmy had a hole in it the size of a ball point pen in it. I suspect you're having the same issue if in fact its only a leak issue when you fill the pig, and all the hoses to your tank (fill and vent line from filler) are on securely.

 

I have a 96 4wd with only 10,000 on the new motor and i'm only averaging about 15-16 on the highway. I'm hoping it impoves as the motor gets more broke in.

 

this isn't about your MPGs... this one is

 

any update on the issue here?