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1987 Chevy R10 Failed Smog Check For High HC and CO

1987 Chevy R10-2WD-350ci/High HC & CO

New cap/rotor-brass terminals. Vacuum lines replaced-checked devices with hand vacuum pump. Is air pump diverter valve vacuum connection supposed to leak down or hold? Sparkplugs replaced-.035 gap. Timing set to 0 degrees. Ran injector cleaner-flush TBI with cleaner-PCV valve also. Inspected EGR valve and checked stroke. Installed fuel pressure regulator rebuild kit. 15 MPH-HC/123 max-136 measured(last inspection this same number PASSED) CO/.57 max-.72 measured. 25 MPH-HC/92 max-92 measured. Ideas?

Answer:

We'd recommend looking into your Chevy R10's fuel feedback system. It appears you Chevy is running too rich. This is indicated by the high CO. The CO is more than likely causing the high HC. So correcting the rich fuel problem will lower HC as well. Start by ensuring the oxygen sensor is working properly, and that the ECU is increasing and decreasing fuel injector pulse width as necessary, depending on the voltage coming in from the O2 sensor. As far as your Chevy's air injection system, the diverter valve should hold vacuum for at least 2-3 seconds. Use a tee and a vacuum gauge to see if you've got enough vacuum coming from the manifold for the air pump diverter valve to operate. posted by SmogTips Support

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