Carburetor throttle body deposits are known to be very critical toward upsetting exhaust emissions and increasing fuel consumption. This study showed that other carburetor areas are just as important. Deposits in the idle air bleed-metering cluster and venturi sections caused sizable increases in emissions and fuel consumption. Because carburetor deposits can cause large deviations from the designed air-fuel metering characteristics, it is extremely important to keep them from forming.
Most carburetor detergents work only in the throttle body area. Because upper carburetor deposits were shown to be critical, additives are needed to control deposits throughout the carburetor.