Chevrolet Repair: EVAP Emission, metro 3, gas mileage

Question
Hi, I have a 1996 Chevy Geo Metro 3 cylinder engine 1 Litre, manual 5 speed transmission.. The service engine soon light came on and the fault code says evap. This light used to come on and go out in warm weather. Now it stays on all the time. The gas cap is tight and tests good at NJ inspection. The engine runs great and gas mileage is terrific.Emissions test good. I understand evap does not affect the way the engine runs. Do you have any pointers as to what I can do to make this problem go away?.Thank You for your time. Sincerely Jerry Gunser

Answer
In most cases this is caused by either a leaking hose in the evap system or a faulty evap canister or controller.

The system needs to be tested using special equipment OR you can try and resolve your problem by simply replacing the gas cap with the EXACT same kind that came with the vehicle when it was new.

It will take about 7 to 10 days for the check engine light to go out as the system has to build up vapor and this takes time.

otherwise, i would not worry about it.