B
FAULT TESTING
Read all of SAFETY and this section before attempting any procedure. Pay particular attention to Notices, Cautions, Warnings and Dangers.
145
Repair and Service Manual
653045
POOR MIDRANGE OR
HIGH SPEED PERFOR-
MANCE
Spark plug fouled
Clean or replace
Dirty air filter
Clean or replace
Brake(s) dragging
Perform brake maintenance
ENGINE OVERHEATING
Damaged or plugged muffler
Clean, repair or replace
Inadequate oil supply
Check oil system, inspect oil pump, change oil, fill to correct
level
Cooling fan clogged
Clean
REPEATED SPARK PLUG
FOULING
Wrong spark plug type
Replace with correct spark plug. See GENERAL SPECIFICA-
TIONS.
Wrong spark plug gap
Replace with correct spark plug. See GENERAL SPECIFICA-
TIONS.
Faulty ignition system
Check and repair if required
Poor quality gasoline
Use correct fuel, check bulk storage tank for proper storage
and handling. See GENERAL SPECIFICATIONS.
Air leak allowing dirt to enter system Repair or replace air intake hose
EXCESSIVE EXHAUST
SMOKE
Wrong oil weight
Replace with recommended oil. See GENERAL SPECIFICA-
TIONS.
Dirty oil
Replace. See GENERAL SPECIFICATIONS.
Crankcase overfilled with oil
Drain and fill to recommended level. See GENERAL SPECIFI-
CATIONS.
Piston rings worn or broken
Replace
Valves worn
Replace
Valve seals or valve guides worn
Replace
BACKFIRING
Faulty plug wires
Replace
Faulty ignition system
Check and repair if required
ERRATIC, SURGING, OR
SUDDEN CHANGE IN
GOVERNED SPEED
Governor bracket spring dragging
Clean and/or oil
Problem with adjustment of accelera-
tor, governor linkage
Adjust
Bent governor arm
Repair or replace
Bent governor shaft
Replace
Governor failure within the rear axle Repair
CONDITION
POSSIBLE CAUSE
CORRECTION
Fig. 2 Powertrain Performance Troubleshooting (Continued)
Property of American Airlines