This won't be caused by the gauge if the low fuel light came on. I have seen fuel level sensor fail and poor connections on top of the fuel tank on the level/pump unit. If your truck was convertered to an in tank pump or has had prior service to the fuel tank, it is posible the connector wasn't pushed on all the way. The rubber seal in the connector will swell up and make it difficult to get the connector on properly. The first thing I would do is check the connector at the top of the tank and make sure it is properly attached and the red locking tab is pushed in all the way. You can access the connector without removing the tank, it can be accessed by getting between the truck box and the frame and on some trucks removing the rear wheel. Check this and we can go from there. Thanks,Richard
THANKS RICHARD , I WILL TRY THAT AND SEE IF THATS THE PROBLEM . IF NOT I GUESS IT WILL BE THE SENDING UNIT .