What would make a 89 Pontiac 6000 stall while idling and the gas fumes are terrible but when you turn on ac it runs smooth doesn't stall but when it's turned off the gas fumes are stiil bad?

Answer 1

When you turn the AC on, the idle automatically increases in rpm slightly, to allow for the increased load on the engine, from the AC compressor engaging. The slight increase in rpm's prevent it from stalling.You could check your TPS (Throttle Position Sensor) readings with a multimeter to make sure they fall into factory specs.

Not sure exactly if you meant raw gas smell, or the exhaust smells?

-Raw gas could indicate a possible gas leak, or a over saturated charcoal canister.

=Exhaust fumes could indicate that it is running overly rich. Rich running can a be several things, including bad 02 sensors, or a faulty ECT sensor (Engine Coolant Temperature) could also be at fault. If it disappears when the AC is turned on, it could be the added AC compressor load on the engine, is allowing the fuel to be burnt more efficiently.

- A new fuel filter, air filter, and spark plugs wouldn't hurt if it's been awhile since new. Check all your spark plug wires at the same time, for resistance, as one or more of them could be bad, or not firmly connected. If one plug is not firing properly, you can get raw gas exiting in the exhaust, thus the fumes..