Questions and Answers

GMC Sierra EVAP Code Q. I have a 1997 GMC Sierra SL. 4.3 litre, V-6 engine with automatic transmission. I recently had the fuel sensor in the gas tank changed and not long after that the engine light started coming on. The diagnostic trouble code shows a problem with the EVAP system.

Is it possible the recent repair in the gas tank is related to this or is it just a coincidence? My mechanic said there is nothing obviously wrong that he can see and is not overly optimistic that he could find the problem even after a close inspection. Any suggestions?

Thanks,
Dave

A. It depends on the code. If it's a small leak or large leak detected, then it's very possible that the tank is the problem, not the tank itself but the sender and it's seal. A dealer has a tool to isolate EVAP leaks that injects smoke into a sealed system and you watch for it escaping.