Runs rich under throttle in Carter W1, WA-1, WO, WDO 1-barrel carbs
High fuel pump pressure
High float level
Warped or bent bowl cover allowing air leak at the gasket
Metering rod spring disconnected from metering rod
Metering rod not gauged properly
Worn metering rod and jet
Metering rod loose in casting
Metering rod disk missing on balanced vent carburetor (Chevrolet)
Bent metering rod
Nozzle installed without nozzle gasket
Air bleed nozzles have to be installed with flat side of nozzle facing up, that is, when looking down from air horn.
A bowl cover with a vent hole, if installed on a balance vent carburetor, will cause a rich condition.
If relief check is stuck closed on carburetors that have relief check for accelerating pump or if the pump vent to the bowl is stopped up, the motor will draw gasoline through the pump system and the carburetor will run rich. If pump bushing gasket is missing, it will let gasoline splash from the bowl over on top of plunger causing pump to give high pressure.
Choker valve hinge stuck in air horn causing carburetor to be partly choked
Dirty air cleaner
Choke not operating properly
Air bleed in air bled nozzles stopped up
Runs rich related to choke
Choke shaft binds
Choke piston binds or is stuck
Air strainer gauze covered with dirt. This prevents hot air from reaching thermostatic coil.
Leak in tubing from stove to climactic control
Leak in choke gaskets
Choke valve binds in air horn
Cork disc in thermostat housing warped
Cork strip shrunk or interfering with operation of the thermostatic coil