Lycoming YO-233-B2A - Page 95

TEO-540-A1A Engine Maintenance Manual
© 2021 Avco Corporation. All Rights Reserved 12-30
February 2021 Page 75
YO-233-B2A Engine Maintenance Manual
Table 1 (Cont.)
Fault Isolation Guide
Problem
Cause
Corrective Action
Ref.
Poor idle cut-off
Incorrect rigging of mixture
control linkage
Adjust in accordance with
airframe manufacturer's
instructions.
Mixture control valve is scored
or not seating properly or O-
ring on mixture jet is broken or
deformed
Leaky valve
Send carburetor to the
manufacturer or repair center
for inspection or repair.
Rough Idle
Incorrect idle mixture
1. Adjust the idler mixture
per instructions in the
section "Idle Speed
Mixture Adjustment" in
Chapter 72-00.
2. Readjust idler speed
72-00
Found only as follows:
—High ambient temperatures
—Engine operating for a long
time at low or idle rpm
1. Operate with cowl flaps in
the full open position.
2. Keep ground operation to a
minimum.
3. Operate with boost pump
on as necessary.
4. Complete the check of the
vent return line for
blockage. Clean if
necessary.
Leak in induction system
1. Examine the flanges,
gaskets and O-rings for
leaks. Tighten or replace as
necessary.
2. Examine for cracked intake
pipes. Replace as
necessary.
3. Examine for loose flange
bolts or loose plugs in
intake port of cylinders.
Torque as required.
4. Examine for fuel stain
evidence of leaking
gaskets. Replace when
found.
5. Examine for fuel drain
valve not properly seating.
OHM