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Forum > Failed Smog Test > Question

1977 Chevy Blazer 305 V-8 motor failing high CO. Why?

My 77 Chevy blazer has a rebuilt 85 305 V-8 with 35+K on it already and Car converter. It has passed emissions test 3/4 past years perfectly - after the cat installed. Last fall I had a carb fire and had to rebuild the Edelbrock 1406 carb, not it fails on CO at LOAD test...even after rejecting it from .095/.098 to .080./.086 with .041/.062 rods and 3 gal of E85 fuel, and 1 gal of denatured alcohol - it still runs 4.84 and should be less than 3.0. What gives here? I am as Lean as can be with it now.
Answer:

If you are absolutely certain the carburetor is adjusted properly, we can only suggest looking into other sources of fuel entering the combustion chambers... such as the EVAP system. Perhaps your Chevy's charcoal canister is saturated. We also recommend conducting a fuel feedback test if this engine's fuel system is electronically controlled.

posted by SmogTips Support

 

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