You recently took your truckMazda b2000 in for a emissions test and you came out failing They said that the engine c o mixture was running to rich where do you adjust something like that on your carb?
I had the same problem. I will start with checking and or
replacing the O2 sensor. If the sensor goes bad it will
automatically make the carb run rich to protect the engine.
http://www.automotivehelper.com/topic404867.htm Also check your
timing, air filter and plugs.