Evap Canister Close Valve

[stutaeng]

I don't think I even have the wire on my truck.

Is the newer truck a GMT-800? I use to drive a work van that was 800 based and had the gas fill problem... in the winter!

The '00 K3500 GMT-400 is the one that had the fill-up issue...

My newer truck that has the EVAP code is a 06 Suburban 2500 GMT800. Code is P0442 (small leak). Changed and tested purge valve and vent valve. I also tested the tank pressure sensor. All those seem fine. Smoke tested and no leaks found. But I did confirm the AC voltage does drop from the tank pressure sensor. It's probably a leak too small to see with the smoke machine outside in my driveway. Maybe a gasket at the fuel pump or the tank sensor itself? I haven't been able to pinpoint.

IIRC, the ECU checks for leaks by closing the vent valve, then opening the purge valve to draw vacuum from the running engine. Then it checks the vacuum decay of the system and determines, (a) system is okay, (b) there's a large leak or (c) small leak.... or something else, and sets the CEL. The test is NOT performed if the fuel tank is less than 15% or greater than 85%.

These videos are superb for understanding these systems if anyone ever needs it:

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[BOWHNT]

Not sure why it is typically sold with the bracket. Pick n pull might be the way to go.