Hi guys...I have a 1986 2 door Honda Civic. It has unleaded petrol and has had the carby rebuilt. Timing is good and has new air cleaner. It does not have electronic ignition.

I am getting lots of black soot all over the back of the car. I am only getting 200 klm on the 40 liter tank. When the car idles I can hear a "tonking" noise. I have adjusted the air/fuel mixture so the carby runs its smoothest and fastest. Plugs are also sooty but the car has good compression. It has had new rings fitted recently and the bore was within spec so it did not require a rebore.

I was wondering if the emission control system has a problem.

Has anyone had experience with poor fuel economy before?