Cleaning & Inspection

1. The following parts should not be immersed in carburetor cleaner:
a. Rubber and plastic parts, electrical solenoids, vacuum diaphragms, accelerator pump plungers and seals.
b. Choke cover and coil assembly.
c. Vacuum break assemblies.
d. Aneroid cavity insert.
2. Clean power valve piston bore of float bowl with soft wire brush. Rotate brush clockwise through full length of bore until dirt and varnish are removed.
3. Thoroughly clean all metal parts in carburetor cleaner. Ensure all fuel passages and metering parts are free of burrs and dirt. Do not pass drills or wires through jet openings. Blow out all openings and passages with compressed air.
4. Inspect upper and lower casting surfaces for damage. On some carburetors, the letters ``MW'' appear on the float bowl. These letters indicate a machined pump well which requires a heavy duty replacement pump. If a replacement float bowl is needed, ensure that replacement has letters indicated.
5. On M4MED models, check dual capacity pump systems as follows:
a. Fill float chamber and pump well with clean solvent, then seal the two pump discharge passages on top of float bowl with two fingers. Push pump assembly downward into pump well. Pump assembly should not fully bottom in well. If pump assembly bottoms fully, check pump cup for wear or damage and pump well for wear or scoring.
b. Check for solvent leaking through or around pump discharge plug or pump valve assembly. If bubbles are evident around plug or valve area, plug or valve may be loose or damage, or gasket under valve may be missing or defective.
c. Seal pump discharge passages of float bowl as outlined in step a, then apply 12 volts to pump solenoid connector. Pump assembly should move in well as solvent bypasses through open valve assembly. If solenoid does not energize when voltage is applied, check for short or open circuit. Replace solenoid if defective.
d. Refill float chamber and pump well, then push pump assembly downward into well until solvent is visible at top of pump discharge passages. Remove pump assembly while observing solvent level. Level of solvent should not drop. If level drops, pump discharge or pump valve assembly check ball may be incorrectly seated or damaged. Repair or replace as necessary.