The weather was nice today so I decided to change my oil and adjust my carb to try to get it running correctly. Ever since I've had the car, it has been running very rich and the best mpg I could ever get was and is 10 or 11. It backfires while sitting still and the idle fluctuates w/ shaking engine. I increased/decreased the idle and the fuel mixture and the car still runs the same. It's very hesitant when I get on the throttle. What can I do? Could it be the fuel filter? or carb itself and I need a rebuild?

 

What year is it, is it a 12a or 13b and what carburetion system do you have?
rx7doctor

 

'83 stock 4 barrel

 

Sounds like your dumping fuel, check sight glasses on float level on sides of carb. Could be needle seat is sticking and not allowing fuel to shut off. Do you hear it
backfiring thru exhaust? Could be retun line is clogged and building too much fuel pressure and causing the problem. Could have sediment from tank getting into system. When was last time fuel filter was changed and good system cleaner
run thru the tank.
When was the last time it had a full tune-up? Wires, air filter, plugs, cap, rotor?
rx7doctor

 

I appreciate your help. Okay, I'll see when I have time. Thanks.