94 suburban not passing emissions test

I'm having much difficulty passing our city emissions test. Does anyone have any tips on reducing emissions? I've done the tuneup and catalytic converter and still failed by 150 ppm on the hydrocarbons. I filled up with 93 octane today and will try to pass again tomorrow. The truck runs good. Any helpful advice would be greatly appreciated!!!

If you take off the air cleaner and start the engine, how does the injector spray pattern look? It should be cone shaped with no dripping from the injector.

Has the 02 Sensor ever been replaced?

//2000CAYukon

Hc's indicate raw fuel or unburned vapors in the exhaust using a tailpipe sniffer, can be caused by an overly rich mixture, misfire, a loaded up evap cannister, fuel contaminated engine oil are the most common sources.

Hc's indicate raw fuel or unburned vapors in the exhaust using a tailpipe sniffer, can be caused by an overly rich mixture, misfire, a loaded up evap cannister, fuel contaminated engine oil are the most common sources.
Thanks for the info. I finnally passed. I think the 93 octane and new plug wires helped. The truck has 320,000 miles on it and still going strong. Never replaced 02 sensor or checked evap cannister. Is that something to be done? No codes appearing. I drive it about 1200 miles a week.

Thanks again!!

I'm having much difficulty passing our city emissions test. Does anyone have any tips on reducing emissions? I've done the tuneup and catalytic converter and still failed by 150 ppm on the hydrocarbons. I filled up with 93 octane today and will try to pass again tomorrow. The truck runs good. Any helpful advice would be greatly appreciated!!!
Having the same problem with my 85, I can't find anywhere the o2 senser go's, but my 84 blazer has one is the sub supposed to have one. and the truck runs lean ??"???