TM 5-4930-227-14
Section V. TROUBLESHOOTING
3-10. General
The corective action recommended is described
This section provides information useful in diag-
opposite the probable cause.
nosing and correcting unsatisfactory operation or
3-11. Organizational Maintenance
failure of the tank and pump units, or any of
Troubleshooting
their components. Each malfunction stated is fol-
Refer to table 3-2 for organizational mainte-
lowed by a list of probable causes of the trouble.
nance troubleshooting.
Table 3-2. Troubleshooting
Malfulwticm
1.
2.
3.
5.
6.
7.
Engine hard to start or fails to
start
Engine misses, operates erratical-
ly or loses power
Engine overheats or knocks
4. Engine backfires
Engine exhaust smoke excessive
Pump fails to operate
Pump fails to prime
Pwbable muse
a. Fuel tank empty
b. Fuel shutoff valve closed
c. Fuel line obstructed
d. Spark plug defwtive
e. Air cleaner dirty or tm full of oil
f. Ignition switch or cable defective
g. Magneto improperly timed or de-
f ective
h. Fuel mixture improper
a. Fuel mixture improper
b, Magneto improperly adjusted or
defective
u.
d.
e.
f.
9.
;:
c.
d.
a.
b.
a.
b.
c.
d.
a.
b.
c.
d.
a.
b.
c.
- Choke partially closed
Muffler clogged
Spark plug loose, dirty or damaged
Governor controls loose or im-
properly adjusted
Other causes
Ventilation across engine poor
Engine dirty
Muffler clogged
Other causes
Fuel mixture too lean
Intake valve sticking
Choke patilally closed
Fuel mixture too rkh
Carburetor float sticking or leaking
Air cleaner dirty or too full
Leak in suction line
Pump not primal
Impeller damaged or worn
Engine speed too low
Leak in suction lines or connections
Pump chamber not filled
Air leak at mechanical seal
C.2rmctiive s.ctiim
a. Fill fuel tank.
b. Open valve ( p a r a 2 - 9 ) .
c. Clean fuel line.
d. Replace sprak plug ( p a r a 3 - 2 3 ) .
e. Service air cleaner ( f i g . 3 - 1 ) .
f. Replace defective ignition switch
or cable ( p a r a 3 2 3 ) .
g. Re-time or replace magneto ( p a r a
3 - 2 4 ) .
h. Adjust carburetor ( p a r a 3 - 2 8 ) .
a. Adjust carburetor ( p a r a 3 - 2 8 ) .
b. Adjust or replace magneto ( p a r a
3 - 2 4 ) .
c. Open choke ( p a r a 2 - 7 ) .
d.
e.
f.
9.
::
c.
d.
a.
b.
a.
b.
e.
d.
a.
b.
c.
d.
a.
b.
c.
Clean or replace muffler ( p a ra
3 - 3 1 ) .
Tighten, clean or replace. spark
plug ( p a r a 3 - 2 3 ) .
Tighten and adjust governor con-
trol ( p a r a 3 - 2 9 ) .
Refer other causes to direct sup-
port maintenance.
Provide proper ventilation.
Clean engine radiation fina.
Clean or replace muffler ( p a r a
3 - 3 1 ) .
Refer other causes to dirwl sup-
port maintenance.
Adjust carburetor ( p a r a 3 - 2 8 ) .
Remove spark plug ( p a r a 3 - 2 3 ) .
Pour 1/2 to 102 of penetrating
oil (W-P-216) into cylinder.
w stand 5 minutes and manually
crank engine. If intake valve
remains stuck, refer to dixwt
support maintenance.
Open choke ( p a r a 2 - 7 ) .
Adjust carburetor ( p a r a 3 - 2 8 ).
Replace carburetor ( p a r a 3 - 2 8 ).
Service air cleaner ( f i g . 3 - 1 ).
Tighten or replace connections or
defwtive hose ( p a r a 3 - 3 5 ) .
Prime pump ( p a r a 2 - 9 ) .
Replace impaller ( p a r a 3 - 1 7 ) .
Adjust carbureiwr ( p a r a 3 - 2 8 ).
Replae suction lines. Tighten loose
or leaky connections ( p a r a 3 - 3 5 ).
Prime pump ( p a r a 2 - 9 ).
Replace seal ( p a r a 3 - 1 7 ).
3-6