i was smelling fuel in the cab when parked and idling, and was worse when backing up. Replaced both fuel tanks and pumps, and can still smell it. Cannot seem to located the source. No obvious signs. My mechanic suspected the tanks due to rust.

Any suggestions?

 

Check for broken or disconnected line going to the charcoal canister on the right front frame rail, also the canister purge valve could be stuck or bad causing it to not pull the gas fumes out of the canister into the intake to be burned..

With that said just check any and all vacuum lines and repair as needed..

 

Thanks. I will check those items and let you know. I just wish I had asked here before spending all that $$$ for tanks and pumps. Oh, well, such is life.

 

Unless something unusual happens, the PCV valve was the culprit! Not plugged in! Plugged it in and no odor. It is hard to see it on the 4.9 liter, but my experienced mechanic should have found it. Also not snug. Will replace grommet next. Thanks so much for your help, White 97 xlt!