I had a recent lift pump failure and replaced it about one month ago. My truck died on the freway just yesterday and I had it towed again. on investigation I find that the lift pump is sucking air. I have 3/16 of a tank of ruel showing on the guage and by my experience with this truck it should be correct.
My question is: what is inside the tank? Is there a pick-up tube that could fall off or something else that could make the suction point be above the fuel level.....or has anybody had a fuel guage go south suddenly, with out warning.
Is it a big job to drop the tank?

 

depending on the year, some models have steel pick ups that rust out and allow air to get in.

 

Thanks Rock,
Got tired waiting for help so I dropped the tank. No metal, all plastic. Tank was empty. The gauge was reading wrong. I have the sending unit out and moving by hand it wouldn't drop below 3/16 level on the gauge. couldn't see anything physically wrong so I disconnedted it and turned on the key. The gauge went to 3/16 and slowely dropped to empty. I plugged the sending unit back in and now it works fine......Go figger!
By the way...dropping the tank is simple enough , but getting the electrical plug and quick disconnect hoses off is a *****. Easy to screw something up if you are not careful and let the weight of the tank hang on the connectors and hoses