d. Cleaning and Inspection.
Clean parts in a well-ventilated area. Avoid inhalation of solvent fumes and
prolonged exposure of skin to cleaning solvent. Wash exposed skin thoroughly.
Dry cleaning solvent (fed. spec. P-D-680) used to clean parts is potentially
dangerous to personnel and property. Do not use near open flame or excessive
heat. Flash point of solvent is 100° F (38° C).
(1) Clean all metal parts with dry cleaning solvent (fed. spec. P-D-680), and allow to dry thoroughly before
reassembly. Do not expose preformed packings, solenoid valve, fuel heater, or fuel thermostat to solvent. Clean these
parts by wiping with clean cloth.
(2) Inspect the needle and seal for nicks, scratches, and other damage which would prevent a good seal.
Replace defective parts.
(3) Inspect the float bowl and cover for cracks, stripped threads, and damage to mating surfaces. Remove minor
surface damage with a fine file and emery cloth, but replace parts that cannot be repaired to prevent leakage.
(4) Inspect the carburetor body for stripped threads. Inspect for damage to the surfaces which mate with the fuel
needle, solenoid valve, and choke valve. Replace the carburetor body if the threads cannot be restored, or if there is
Do not attempt to clean the fuel jet with stiff wire or any hard, sharp object. If the
orifice becomes enlarged, proper fuel flow adjustment may be impossible.
(5) Inspect the fuel mixer and fuel jet for clogging, damaged threads, and enlarged or damaged fuel and air flow
holes. Clean off carbon buildup with a wire brush. Clean up the threads, if possible, but replace either part if there is
damage which could affect fuel flow.
(6) Inspect the fuel heater for continuity with a low voltage test light or ohmmeter. Replace the heater if it is open.
(7) Test the fuel thermostat for continuity. There should be no continuity at 55° ± 6°F (9.4° to 16.0°C), but there
should be continuity at 40° ± 6°F (1.1° to 7.8°C). Replace the thermostat if it does not meet these specifications.