Help!!
#1
#2
There is a very good chance that there is a leak in one of the hoses to the charchol canister located underneath the truck, or in the engine compartment. This is fairly common on these trucks after they are a few years old. The canister in located behind the driver's side up in the frame rails. If the hoses look corroded or weather checked at all, replace them. It will cost you a lot less if you do them yourself, rather than a dealer. They are just typical rubber hose--nothing special about them. You might also consider springing for silicone so you don't have to do it again for a long time--if ever. Don't forget the one at the solenoid in the engine compartment, just follow the lines back from the canister.
#4
Yeah it has to be a leak or your pump may be messd up. Here is how the system know there is a leak. At certian intervals the your onboard diagnostics ll (obd-ll) will pressurize your tank and all components of the fuel system for leaks. The pcm monitors the leak detector pump to determine if the system has a leak or problem. If it's not a leak then try pulling fuse #23 and turning your ignition all the way on to reset your pcm, replace the fuse and see if it fixes the problem