So ive got a SES code PO442, means a small leak in the evap emissions system...cant be the gas cap, because when i fill up, the pump doesnt shut off when the tank is full, it overflows from the fuel filler hose or tank, something under the truck, because the paint doesnt get gas on it. Would a leak in that system cause the pump to malfunction? I tightened the hose clamps for the filler hose and reset the light, but it came back on. I replaced the pump not long ago, and had to drill a hole for the sensor (1 wire vs. 2 wire pump) but i really dont think thats the source of the problem. Truck is an 01 silverado with the 4.3...any ideas?