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Q: Engine revving, backfiring, cannot accelerate past 40 mph - 1990 Chevrolet G30

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Whenever I rev the engine, I notice backfiring. I think it's coming from the carburetor area. It makes a popping noise. I'm unable to accelerate past 40 mph. The engine never stops revving and cannot idle down. I had the fuel filter replaced. The carburetor hose to the distributor cap is good. What might be the problem?

The poor performance and backfiring through the intake you mention are signs of a "lean" condition - not enough fuel for the amount of air flowing through the engine. You may have a vacuum leak or Idle Air Control valve problem. If you find you are still having issues with this, a professional expert from YourMechanic can come to your home, and diagnose the backfiring issue and make any necessary repairs.

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