So I've noticed that it seems like I'm losing more fuel than I should be. What could be the cause of that? What could I do too diagnose this problem?

 

Are you just getting bad gas mileage? Or do you smell fuel? Someone siphoning your tank?

 

I'm getting bad fuel mileage. My truck is 3.9l v6 1500 and I was only able one time get great fuel mileage out of it. That one time I filled it all the way up and gonna 200 miles and just brun up too half a tank. Ever since than I'll fill it up and go 40, 50 miles and burn up to half a tank.

 

For what I know those 3.9l v6 suppose to save good fuel mileage on them compared too 5.2 or 5.9 haha

 

There’s a lot of factors, cat getting plugged up, bad o2 sensors, in need of a full tune up, plugged Pvc system, plugged charcoal canister, or it could be as simple as a faulty sending unit showing incorrect fuel level?

either way your probably going to have to do some diagnostic on it…….I have a 3rd gen quad cab 8ft bed with the 5.9 gas and I get 11-12 normal driving, around 14-16 at steady 55-70 mph

theres got to be something going on, but we can’t diagnose through forum because and issue like that there’s so many factors to consider

but at same time my 95 single cab short bed with the 5.9 that I did ALOT of work to, still only got 8 mpg on a good day, maybe 10 doing 55-70 on long distances