ok.. wed. we used this truck (GMC 3500 P/U for the first time in a couple months. Was pretty low on gas, but sat at jobsite. Then wen to start, and no go... just cranking. Ok well obviously out of gas... so we get gas in it and fire ... nothing now the starter is going.. so after jumping the selonoid and getting it to crank over , but still no start. NOW What.... well i decided the fuel filter must be clogged.. so we change and wiht a shot of starting fluid the truck started and ran back to the shop./ Today i try starting and no go... just cranks and cranks ... What could this be????