petrol tank venting ecu control

[WEG1192 at aol.com]

This is a long shot, but could it be possible that you have two failures at 
once? Your tank relief valve could be failing and the canister purge valve is 
putting engine vacuum directly to the tank? I once had a 1983 Camaro Z28 with 
the CCC quadrajet on a 305 H.O.. My engine all of a sudden started blowing 
black smoke at idle, but ran fine at part throttle and above. Using a dwell 
meter to diagnose the problem, I determined that the carb was being told to 
lean out completely at idle, yet the fuel was still getting in there somehow. 
So I started pulling vacuum hoses until I found the one dumping all the fuel 
into the engine. Turns out my charcoal canister purge valve had a split 
diaphragm and was leaking fumes directly from the tank to the engine. 
Replaced the valve, problem solved. I can imagine that if the tank vacuum 
relief valve was defective, I would have sucked that tank into a peanut.

JW
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