GMC Sierra EVAP Failure Causes Stalling After Refuel

Had a similar issue with my GMC Canyon (2012, gas engine) last year. The symptoms match a faulty EVAP system, which was causing vapor lock and idle problems, especially after filling up. The root cause was a combination of a clogged purge valve and deteriorated vapor hoses. The EVAP system prevents fuel vapors from escaping into the atmosphere, and when it fails, it can cause exactly these symptoms, rough idle, stalling, and check engine warnings. The automotive repair involved: Cleaning the EVAP system passages, Replacing the purge valve, Installing new vapor hoses from the fuel tank, Verifying proper gas cap seal This was a serious issue requiring immediate attention, as a malfunctioning EVAP system can lead to increased emissions and potential fuel system damage. The repair took about 4 hours at the shop. The problem hasnt returned since fixing these components. Would recommend getting it properly diagnosed with a scan tool first, as similar symptoms can come from other fuel system issues. Most important is finding a reputable shop that specializes in fuel system diagnostics.

Thanks for sharing those details about your Canyon EVAP system repair. Crazy how similar our issues sound, especially with that rough idle after filling up. Dealing with the same stalling problem on my Sierra, so its helpful to know the purge valve and hoses were the culprits in your case. The pressure sensor on mine is triggering the check engine light constantly. Just wondering, do you remember roughly how much you paid for the full repair? Also, did any other emission system problems pop up since getting it fixed?

Had the repair done last week actually. The total bill came to 175 Euro for fixing the clogged hoses, which turned out to be the main culprit affecting the tank ventilation system. No additional emission problems since the fix. The tank ventilation valve is working perfectly now, and the pressure sensor readings have stayed normal. The automotive repair shop found that debris had built up in the vapor lines over time, restricting proper flow. The best part is the check engine light hasnt come back, and the fuel tank pressure is maintaining correctly. They also verified the gas cap seal while doing the work, which was actually still good in my case. Worth every cent considering how smooth it runs now, especially after refueling. No more stalling issues at all.

Thanks everyone for the feedback. Finally got my Sierra fixed yesterday. The repair shop found exactly what we discussed, a clogged purge valve and some worn out vapor lines. Total cost came to 350 Euro which included replacing the pressure sensor too since it was giving false readings. They did a full system purge and cleaned out all the EVAP passages. The check engine light cleared up right away and hasnt come back. First fill-up since the repair went perfectly smooth. No more stalling at idle, and the engine runs like new. The gas cap seal was actually cracked too, so they replaced that while they were at it. Glad I got it done at a proper automotive repair shop this time instead of trying quick fixes. Feels good not getting ripped off for unnecessary work like before.