TM 5-4310-335-14
Table 4-2. TROUBLESHOOTING (Continued)
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
(1)
Remove breaker point cover assembly. Inspect point gap and adjust if necessary.
(2)
Loosen screw and slide timing hold cover to expose timing marks on flywheel.
(3)
Remove rocker arm cover nearest flywheel.
(4)
Rotate flywheel counterclockwise and observe intake valve and rocker arm continue to rotate flywheel until valve
closes, and stop when the ignition mark on the flywheel is aligned with pointer.
(5)
If points of breaker point assembly are not just beginning to open, the ignition cam must be reset on the lower
breaker point assembly.
(6)
Loosen the screw and rotate the ignition cam counterclockwise until points begin to open. Then tighten screw.
(7)
Install rocker arm cover. Install breaker point cover assembly and close timing hole cover. Tighten screw.
d.
If spark plug cables require replacement, loosen connector nut on each end of cable, remove and replace cable. If
spark plug needs replacing, remove spark plug. Before installation of new spark plug measure the electrode gap with a
wire or leaf thickness gage. A slight drag should be felt, when monitoring the correct measurement. The desired
clearance is 0.028 to 0.033 Inch. Adjust the gap by bending the outside electrode until the gap is properly set.
e.
If the ignition switch is defective or damaged, replace it, as follows:
(1)
Tag and disconnect electrical leads.
(2)
Remove nut front outside of flywheel fan cover and push switch through cover.
(3)
Remove ignition switch.
If engine still fails to start, go to Step 4.
Step 4.
Check fuel filter to see If it is clogged or filter element is dirty. Remove outlet line from the filter to check flow of fuel. If no fuel
or a very small flow of fuel is noticed at the outlet side of the filter, remove and clean the fuel filter.
If fuel flow is sufficient, go on to Step 5.
WARNING
Dry cleaning solvent P-D-680, or P-S-661, used to clean parts is potentially dangerous to personnel
and property. Avoid repeated and prolonged skin contact. Do not use near open flame or
excessive heat. Flash point of solvent is 100 (38 ) - 138 (59 ).
F
C
F
C
a.
To remove and clean the fuel filter, shut off fuel at top of filter then loosen thumbscrew holding bowl to the filter,
swing the ball to one side and remove the bowl. Remove and clean the filter in an approved cleaning solvent.
Inspect the gasket and replace the fuel filter If necessary.
b.
After cleaning install the gasket firmly into the filter head. Install clean filter element and then install the bowl.
Swing bail under bowl and tighten thumbscrew. Turn on fuel. Check for leaks.
Step 5.
Remove fuel line from fuel pump to carburetor. Turn engine over using the starting rope. If fuel flow is coming out of the fuel
pump in a steady spurt, go on to step 6. If no fuel is seen coming out or a weak flow is noticed, remove and repair or replace
the fuel, pump. Disconnect fuel line and blow out line with compressed air.
WARNING
Dry cleaning solvent P-D-680, or P-S-661, used to clean parts is potentially dangerous to personnel
and property. Avoid repeated and prolonged skin contact. Do not use near open flame or
excessive heat. Flash point of solvent is 100 (38 ) - 138 (59 ).
F
C
F
C
a.
Remove the fuel pump, first disconnect the fuel lines. Remove two screws th at attach fuel pump to engine.
Remove fuel pump and discard gasket.
b.
Clean with an approved cleaning solvent and dry thoroughly. Inspect body for cracks, breaks, evidence of
leakage and stripped or damaged threads. Inspect plunger arm for cracks, breaks, distortion and excessive
wear. Inspect spring for cracks, breaks, or distortion, Test fuel pump for proper operation by holding fuel
pump and work plunger arm up and down. By holding a finger lightly over the inlet side of the pump, you
should feel a auction. Test pump outlet pressure by attaching a pressure gage to the outlet side of the pump.
The pressure reading should be 3.0 to 4.5 psi. Inspect fuel lines and fitting for cracks, breaks, evidence of
leakage abnormal bends, dents and stripped threads. Repair or replace any damaged or defective parts.
Step 6.
Check the carburetor and throttle controls for adjustment. Adjustment Is as follows:
a.
With engine stopped, turn main adjustment needle and idle mixture needle fully clockwise to c lose.
b.
Turn main adjustment needle three quarters of a turn counterclockwise, and idle mixture needle one-half turn
counter clockwise. Start engine and run until warm. Check packing nut for tightness. Tighten as required.
c.
Apply load and observe engine exhaust. If exhaust is black, close main adjustment needle. It engine misfires or
seems low in power, open main adjustment needle until it delivers maximum power with minimum exhaust smoke.
d.
If engine application has a throttle and speed adj ustment, regulate idle mixture In a similar manner.
e.
Regulate Idle RPM by turning Idle speed regulating screw clockwise or counterclockwise.
If adjustment of the carburetor and throttle controls does not resolve the problem, replace the carburetor and/or throttle
controls.
(1)
Remove the two screws and remove throttle control housing cover.
(2)
Remove screw and disconnect throttle lever from shaft.
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