Air/Fuel Mixture Control (Air Flow Sensor)
- Remove rubber bellows to expose plate in sensor. Disconnect electrical connectors on auxiliary air valve and control pressure regulator, then operate fuel pump for ten seconds to build up control pressure.NOTE: Directions given for moving sensor plate apply to engines where sensor plate moves UP with air flow. Reverse directions if servicing an engine where air flow moves DOWN.
- Lift sensor plate slowly with magnet or pliers. Resistance due to control pressure should be constant throughout range of plate. Release plate slowly, lever and control piston should follow.
- Lift plate, then return it rapidly to lower position. The piston moves more slowly and should be heard hitting the lever. If not, control piston is sticking. Remove 3 screws from fuel distributor and lift off of air flow sensor housing. Be careful not to drop control piston.
- Clean plunger in gasoline. Remove any deposits with finger nail; DO NOT use tools. Slide plunger in and out while turning it. If any sticking or binding is felt, replace fuel distributor.
- Reinstall fuel distributor. Check air flow sensor plate alignment. Plate should be even with bottom rim or 0.02" (0.5 mm) lower. If not, bend spring to correct, or reposition stop pin (tap lightly with punch).
- Plate should be centered in housing. If not, loosen center screw and align plate with 0.004" (0.1 mm) feeler gauge at four points around rim. Apply Loctite and tighten screw.