TM 5-3740-214-14
Table 4-3. Troubleshooting Chart (Continued)
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
ENGINE OPERATES ERRATICALLY (Continued)
Step 2. Check fuel tank cap.
a. Remove cap and check the air vent.
(1) If cap vent is plugged, clean it out and return it to the tank. Go to Step 2b.
(2) If cap is ok, go to Step 3.
b. Start engine.
(1) If engine runs smoothly, the problem is solved.
(2) If engine still operates erratically, go to Step 3.
Step 3. Check carburetor.
CAUTION
BE CAREFUL not to use force when turning the needle valves in and out. Force will damage the
valve seats.
Figure 4-59. Carburetor
a. Adjust needle valves.
(1) Turn main fuel needle valve to the right (clockwise) until the engine slows
down.
(2) Turn main fuel needle valve back to the left (counterclockwise) until engine
slows down.
(3) Turn main fuel needle valve back to the right to a position halfway between
the slow down points.
(4) Go to Step 3b.
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