TM 9-2320-211-20
Table
2-3.
Troubleshooting--Vehicle--Continued
Item
No.
Malfunction
Probable Cause
Corrective Action
GASOLINE ENGINE--Continued
5 Engine misfires at high speeds.
a. Faulty ignition system
Refer to table 2-4, IGNITION
SYSTEM.
b. Improper valve adjustment.
C h e c k and adjust valve clearances
Refer to item 2f
c.
Restricted fuel lines or fuel filter.
d.
Defective fuel pump
Refer to item 2g
e.
Spark plug gap improperly set,
Adjust gap (para 2-121)
6 Engine idles too fast.
a.
Improper carburetor idle ad-
Adjust carburetor idle mixture (para
justment.
screws (para 2-68).
b. I m p r o p e r a c c e l e r a t o r l i n k a g e
Adjust linkage (para 2-67)
adjustment.
Inspect gaskets for leakage. Replace
c. Intake manifold gaskets leaking.
if necessary (para 2-44).
7 Engine overheats
Refill cooling system (para 2-108).
a. Low coolant in system
A d j u s t carburetor (para 2-65). In-
b. Lean air-fuel mixture
spect engine for leaks at manifold
and carburetor gaskets.
Check ignition timing and adjust as
c. Late ignition timing
necessary (para 2-120).
8 Engine falters
Replace carburetor
C l o g g e d or worn carburetor parts.
Notify supporting maintenance
p e r s o n n e l if engine still falters.
9 Engine backfires
Check cables for proper firing order
a. Crossed spark plug cables.
sequence (1-5-3-6-2-4).
Inspect distributor cap and coil for
b. Cracked coil or distributor cap.
tracks o r carbonized spots, in-
d i c a t i n g current leakage. Inspect
all carbon tips in cap. Replace cap
or coil if any cracks or car-
bonization is noted (para 2-119).
c. Out of time
Check ignition system timing (para 2-
10 Excessive oil consumption.
a. Oil leaks
Inspect engine, engine components,
and ground under engine for oil
leaks.
Tighten leaking connections and
repair or replace broken lines.
Refer to item 20.
b. Engine overheating
Check ventilation breather and
c. Clogged cylinder block ventilation
strainer.
breather and strainer.
Service as indicated in
d. Poor compression
T e s t compression on all cylinders
between cylinders is noted, notify
supporting maintenance personnel.
e. Excessive low-speed driving in too-
Vehicle must be operated in proper
high gear range.
g e a r ratio for desired speed ac-
cording to road conditions.
1 1 Engine oil pressure low as in-
a. Inadequate engine oil supply; low
Check engine oil for proper level and
oil level.
proper viscosity; replenish oil (LO
dicated by oil pressure gage.
9-2320-211-12).
* Replace gage (para 2-148).
b. Defective oil pressure gage.
c. Defective oil pressure sending unit.
* Replace sending unit (para 2-163).
d. Improper oil viscosity
Drain and refill with oil of proper
viscosity.
12 Excessive noise on increased
Insufficient lubrication.
Check for low oil pressure and high
oil consumption. A d d o i l i f
required.
Notify
supporting
maintenance if these conditions are
not normal.
13 Excessive noise with engine idling.
Insufficient lubrication
Refer to item 12
* Refer to footnote at end of table.
