Cessna 150 STANDARD Service Manual page 144

11-9. TROUBLE SHOOTING (Cont).
TROUBLE PROBABLE CAUSE
REMEDY
ENGINE DOES NOT SHUT OFF Fuel leakage thru primer.
Repair or install new primer.
WITH MANUAL MIXTURE CON-
TROL IN IDLE CUTOFF POSI- Linkage does not permit idle
Rig in accordance with paragraph
TION.
cutoff lever to reach OFF posi-
11-53.
tion.
ENGINE RUNS ROUGH AT HIGH
Loose mounting bolts or rubber
Tighten bolts or replace mount
SPEED.
bushings defective.
bushings.
Propeller out of balance.
Remove and balance.
Spark plug gasket leaking, gap
Replace damaged parts.
too large or insulator damaged.
Ignition cable insulation damaged.
Test for leakage at high voltage.
Replace damaged ignition lead.
Excessively lean fuel-air mix-
Clean fuel strainer, carburetor
ture.
screen and carburetor main jet.
SL UGGISH OPERATION AND
Throttle not opening completely.
Rig per paragraph 11-52.
LOW POWER.
Spark plugs fouled or improperly
Remove, clean and regap or install
gapped.
new plugs.
Carburetor air heat valve open.
Rig in accordance with paragraph
11-54.
Damaged contact breaker or
Overhaul magneto.
capacitor.
Fuel-air mixture too rich or
Overhaul and adjust carburetor.
too lean.
HIGH CYLINDER HEAD
Low grade of fuel. Drain and fill with correct grade
TEMPERATURE.
of fuel. Refer to Section 2.
Lean fuel-air mixture.
Refer to Owner's Manual for
correct leaning procedure.
Excessive carbon deposits in
Install new cylinders and piston
cylinder head and on pistons.
rings or new engine.
Cylinder baffles loose or bent.
Check all baffles and correct.
Dirt between cylinder fins.
Clean thoroughly.
HIGH OIL TEMPERATURE. Low oil supply. Replenish.
Oil viscosity too high. Refer to Section 2 for seasonal
grades.
Prolonged high speed operation Hold ground running above 1500
on ground.
rpm to a minimum.
11-6