Is it normal for a carbed engine to get bad mpg in cold weather? Here in WI it was 6 degrees when I went to work this morning. By the time I got to work which is 15 miles away I went from exactly a quarter tank to touching E. My drive is on 35mph roads with about 5 stoplights, then the last 3 miles on the freeway. Now my car has a non CC Q-jet on it. It starts right up in the morning and idles fine for a few seconds, then it starts to shake and jump around and will die if I don't keep my feet on the brake and gas at the same time. When I leave my driveway and hit second gear it drives fine again. No shaking, sputtering, nothing. I will try and make a video if it help at all. Any help is appreciated.

 

Pretty much all cars get worse MPG on winter fuel blends. The gas gauge is inaccurate. Mine does the same thing. When its showing a quarter tank, I know there is a lot less than a quarter tank in there.

Check the choke linkages, it might be jamming.

 

If your concerned about MPG the ONLY way to measure is to fill the tank till the pump stops, drive around a few days, fill it up again, and divide miles drive by fuel used. My fuel guage reads 3/4 with a full tank and stays on empty for about 50 miles or so. Sounds like you've had a choke issue this whole time. At least thats where I would start. On 10*F mornings I give two full gas pedal pumps and mine starts right up. I let it run for about 60 seconds or so then kick the idle down.

 

well most of my gauges are wrong so that could be it too. Well yesterday I played with the choke idle speed and got the car to idle by itself at 1400 rpm but it was still shake and buck around. I went around to the back of the car to listen to it (sounds like it's cammed ) and saw all this black crap on the snow. Not sure what it is, any ideas? Also how long should it run before kicking the idle down?

 

It's normal for it to kick out a 'little' black stuff, especially if it's running rich (choke on). The water in the exhaust will spit out, carrying with it a little gunk. Once the exhaust gets hot enough to vaporize all of the water it will stop. This will be worse if the motor was not run to full operating temp last time or two it was run.

Time on high idle should vary depending on temperature. It should run long enough for the engine to warm up to a smooth curb idle.

Before adjusting anything, ensure the choke is properly functioning. It should slowly open as the engine is running until it is fully open, normal to the plane of the carburetor. Should take a few minutes, longer if it's colder.