re: GMC Yukon - Fuel Pump Shuts off Constantly While Filling Tank (SOLVED: update pg 2)

At a minimum its the vapor cannister. The cannister has a sponge in it that keeps the activated charcol pettets from entering the fuel line. The foam sponge degrades and the fuel lines get full of the small black pellets. You will have 3 hoses running to the cannister. One goes to the vent valve, one goes to the purge valve (on top of the engine), and the other to the gas tank. The line to the gas tank is actually 3 lines that merge. They will all be full of pellets. Mechanic will tell you that you must drop the tank. I recently changed mine by vacuming the hoses multiple times and running 400 lb mono through the lines. Compresses air will blow the pellets into the tank. Remove the purge valve and shake it to remove pellets, and then clean this line. (It will not hurt to use compressed air on the purge line if it is first disconnected at the cannister, but still use mono)This condition will not cause a check-engine light to trip.