I replaced my fuel pump on a 2000 1500 Silverado due to faulty gauge readings when ¾ full and above. The replacement was done by lifting the bed rather than dropping the tank. I replaced it with a Delco labeled pump. After 2 weeks and over 900 miles into a trip, I suddenly get the P0442. Thinking I pulled too hard on the fill neck and seeing it very rusty I replaced it. I doubled checked the connections on the tank. I further removed the new pump and greased the gasket to make sure of the fit which is very tight. The light came back on within 200 miles and a half of tank of fuel. Swapping fuel caps with the identical truck at work yielded the same 200 miles result.Before I get into the smoke test and other items, am I missing something simple? It is bothersome that the initial fault came on much later and now comes on right away. All new electrical connections at the pump were soldered, not crimped. Hopefully the new pump sensor is not bad. I just have a simple code reader.

 

This might be a coincidence, I'd check evap system hoses

 

if your scan tool has bi-directional control...see if it will cycle the vent valve open and closed...if you don't hear it click during opening and closing...the valve may be stuck...other than that smoke test is the way to go.