Cessna 150 STANDARD Service Manual page 143

11-9. TROUBLE SHOOTING (Cont).
TROUBLE
PROBABLE CAUSE
REMEDY
ROUGH IDLING (cont). Manual mixture control set for Use full rich mixture for all ground
lean mixture. operation.
Fouled spark plugs. Remove and clean. Adjust gaps.
Test harness cables. Inspect
contact breakers.
If
persistent,
perform top overhaul.
Priming pump leaking.
Repair or replace.
Small air leak into induction
With mixture control at IDLE
system. CUT-OFF, ignition switch OFF
and throttle open, brush soap
lather around tube joints and
carburetor mount flange, one at
a time, and turn propeller back-
wards to check for bubbles at
points of leakage. Tighten con-
nections or replace damaged
gasket or seal.
Leaking accelerating pump. Repair or install new carburetor.
Defective engine. Check compression and listen for
unusual engine noises. Engine
repair is required.
ENGINE RUNS TOO LEAN
Manual mixture control in Rig control in accordance with
AT CRUISING POWER.
wrong position. paragraph 11-53.
Carburetor partially restricted. Remove and clean.
ENGINE RUNS TOO RICH Manual mixture control in wrong
Rig control in accordance with
AT CRUISING POWER. pOSition.
paragraph 11-53.
Restriction in air scoop or filter Remove restriction. Clean filter.
partially restricted.
Carburetor air heat valve open.
Rig in accordance with paragraph
11-54.
ENGINE DOES NOT ACCEL-
Cold engine. Warm up longer.
ERATE PROPERLY.
Mixture control set for lean mix-
Set control at full RICH pOSition.
ture.
Restriction in carburetor air Remove restriction and clean filter.
intake.
Restriction in carburetor jets, low Clean and repair carburetor.
float level, plugged fuel screen.
Idling setting too lean.
Refer to paragraph 11- 37.
11-5