I just swapped to a genuine Weber Carb with a mechanical fuel pump swap on my Automatic b2200. I did the swap mainly to try and get better fuel economy because I have only been getting 220km to 40Litres a fuel on average so about 18L/100km so about 13 mpg. It has made no difference, I have tuned the carb to the settings given from the manual with the carb and it still has bad fuel economy so I think there maybe an issue somewehere else. I just changed the oil today as it was black, my next thing ill check is the spark plugs but they look pretty new visually, the cylinders are making good compression. It drives pretty normally pulls well, doesnt produce any coloured smoke or smell from the exhaust, I should also note that the exhaust is in need of replacment as it has a few holes in it and the muffler has a huge hole in it.

My next steps are to change the PCV valve, I also noticed the vacumn line to the transmission modulator was a bit wet looking I disconnected it and tried driving the car and it wouldn't shift gears so the modulator is working I guess but I think it may be sucking in some fluid, maybe its burning a bit of ATF fluid and its contaminating the spark plugs (The ATF fluid needs topping up every now and then).

Im a little stumped, can anyone shed some light onto what it could be causing these issues?

 

How did you determine this?