Once upon a time, my carburetor cultus could give a 14kmpl average locally without AC. I once even got it to 16 by driving with RPMs below 2k and with the excessive use of engine braking and driving at times when traffic was clearer.
I now get a fuel average of 6.46 kmpl with AC. I don’t have the tools to check spark pugs, (which were darkened the last time they were out, but I’ve had a carb adjustment and service and setting done since then). I took off the chrome exhaust tip, cleaned it up really well and observed the the silver rim within. Over the course of 2 weeks, it darkened significantly. While there has been no smoke, there is clear evidence that the car is running rich and I don't know what to do. I feel like it has something to do with the ignition timing being maladjusted due to a shaved head and a thick 2 or 2.5 mm gasket leading to affected compression rates. I can't tell if the car has spark knock.
Weren’t these cars advertised as getting 44 mpg as a geo metro which is roughly around 18kmpl IIRC? Is that because of the Throttle body injection? I am at a crossroads and do not know what to do with this fuel average and how to fix this.
When we got carb serviced for the first time, It would be an understatement to say I was impressed with the results. The sound of the engine had changed completely. It had lightened, like it felt physically light and soft, like a hum( It was a whine instead of a rumble) when accelerating. The drive and pickup were exhilarating and it gave me some insight into what this car might have been like when new. It deepened my sense of fondness and appreciation for this car.
Not a week later the sound was rough and heavy-ish as if it had a sore throat and the pick-up had diminished from what it was to normal or unsurprising and the car was smoking grayish black when accelerating but not on idle. We went back and an adjustment fixed the smoke problem but, the car is just not the same as it was. Evidently, there are still fuel mixture issues as demonstrated by my exhaust tip experiment.
What are your suggestions, please tell me a solution