Please help.... My 82 Z28 has started backfiring when i turn it off. What could cause this and what would be a good course of action to solve this. There is also a strong gas smell while engine is running. Thanks for any help that you can send my way.

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Let the good times roll

 

Sounds like an ignition problem rather than the carb. Check the condition of the plugs, wires, cap, rotor, advance weights and springs etc, check vacuum advance operation and connection (ported vacuum)... Backfiring throu the carb when you shut if off is usually caused by an over heated motor. carbon buildup in the combustion chamber. over advanced ignition timing, wrong heat range spark plugs, low octane fuel. Check the anti dieseling solenoid on the carb throttle linkage for proper operation. It should open the throttle when you turn the key on and touch the gas and close off the throttle when you shut off the key. Check the exhaust manifold heat riser valve for proper operation. IF the manifold has EGR on it, check to see if it closes at idle and opens as you open the throttle. Could also be a burned or leaking intake valve. Sometimes its just a bit of carbon sitting on the valve seat. Do a compression test to see if the cylinders are sealing. if one is low, add a bit of oil into the spark plug hole and repeat the test.
If it remains low again it's either valves or head gasket.

[This message has been edited by F-BIRD'88 (edited November 07, 2001).]

[This message has been edited by F-BIRD'88 (edited November 07, 2001).]

 

Thanks for the information, but let me add that the backfire is coming from the exhaust rather than the carb (at least that is what it sounds like). I've been running the car as is for about 8-9 months with no problems of this type. The car also feels like it will cut off at any second while sitting at idle or in park, this is why I suspected a carb issue. Thanks again.

 

Oh.... Backfiring in the exhaust is raw fuel in the exhaust. Thake the carb off. Flip it over, ther is two fuel passages
with lead plugs in the ends. The plugs are leaking fuel, drippeling into to intake.
This is the fuel smell you're smelling.
clean off all the carbon and stuff off the plugs and coat with JB weld and leave it overnight to set up. Then reinstall
with a new carb gasket. This is a very common problem on Q-jets. Hope this helps...

 

Thanks for the help I will work on that this weekend.