Rear tank works, I think
So in spite of the fact that the previous owner assured me that the rear tank worked, I decided to test it out for myself. Filled up front tank, thought I'd put a few gallons in the rear tank just for good measure. At about two gallons on the rear the pump shut off. Tried a few more times for good measure, definitely being shut off. Couldn't see any fuel in the filler neck, so just decided maybe the tank was already full.
Started truck, switched to rear tank. Kept right on purring. Well, clacking. But the gas gauge never rose above 1/4 tank. Wasn't sure if this was a problem with the tank or the gauge so left it on the rear tank and drove. A few days later the gauge was off the scale and no longer visible. Finally started getting some hesitation in the motor, switched back to the main tank and checked mileage. Looks like I drove about 100 miles on the rear tank.
So I think I need to have someone check the rear tank. Float needs adjusting or replacing, tank may need cleaning.......whaddya think?