Before I get into diagnosing any electrical problem that I may not have, this is what is going on.

Recently I let my front tank get low and when I put fuel in it, it took some time before the gauge started showing fuel level.. Today I added about 10 gallons to the front tank and it registers empty. Because of the first experience, I assumed I had a bad float. So I goosed the truck and hit the brakes hard to slosh the fuel and the gauge went up to about half full and returned to empty. Repeated that several times with the same results. So I assume my front tank float is sunk or partially stuck. I have not changed the FDM in either tank since I got it at 87K. It has about 95K on it now. Truck runs fine on either tank so is it probably a stuck/sunk float? Thanks for any opinions. Sandy

 

That would be my guess. Yeah.

 

Added a little MMO to my front tank with the stuck float. I have been using Hurricane "Just in case" generator fuel since we are now out of season. Fuel had Stable in it but ...... After about 20 minutes of driving today with the MMO the float came unstuck and rose to the proper level. I don't know if the MMO worked or just time but it is working now. Thanks for the reply SFaulken and rla

 

Heh, MMO is what I would have suggested, I've seen it "resurrect" more fuel gauges and low pressure pumps on the bricknoses than I can count. Dunno whats in it, or why it works, but I always try it before changing pumps or sending units.