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7.1 ENGINE TROUBLESHOOTING
The following troubleshooting chart is to be used to
isolate engine problems and give possible causes and
corrective action responses.
The troubleshooting key is generic and can be used for
several types of engines. Use only those possible
causes and corrective actions that apply to the unit.
SECTION 7 - ENGINE
ENGINE TROUBLESHOOTING
PROBLEM PROBABLE CAUSE CORRECTION
Black Exhaust Restriction in air cleaner Remove obstruction
Poor compression Repair per instructions in manufacturer’s manual
Incorrect grade of fuel Use fuel recommended in manufacturer’s manual
Leaking cylinder head gasket Replace per instructions in manufacturer’s manual
Sticking valves Repair per instructions in manufacturer’s manual
Worn cylinder bores Repair per instructions in manufacturer’s manual
Pitted valves and seats Repair per instructions in manufacturer’s manual
Broken, worn, or sticking piston rings Repair per instructions in manufacturer’s manual
Blue/White Exhaust Incorrect grade of lubricating oil Use oil recommended in manufacturer’s manual
Poor compression Repair per instructions in manufacturer’s manual
Leaking cylinder head gasket Replace per instructions in manufacturer’s manual
Worn cylinder bores Repair per instructions in manufacturer’s manual
Worn valve stem guides Repair per instructions in manufacturer’s manual
Broken, worn, or sticking piston rings Repair per instructions in manufacturer’s manual
Difficult Starting Restriction in air cleaner Remove obstruction
Low cranking speed Check connections to electric start (if applicable)
Controls not in correct operating position Reset controls
Blocked fuel feed line Remove obstruction
Choked fuel filter Clean or replace filter
Poor compression Repair per instructions in manufacturer’s manual
Blocked fuel tank vent Remove obstruction
Incorrect grade of fuel Use fuel recommended in manufacturer’s manual
Sticking valves Repair per instructions in manufacturer’s manual
Worn cylinder bores Repair per instructions in manufacturer’s manual
Pitted valve stems and seats Repair per instructions in manufacturer’s manual
Broken, worn, or sticking piston rings Repair per instructions in manufacturer’s manual
Erratic Running Restriction in air cleaner Remove obstruction
Controls not in correct operating position Reset controls
Blocked fuel feed line Remove obstruction
Choked fuel filter Clean or replace filter
Poor compression Repair per instructions in manufacturer’s manual
Blocked fuel tank vent Remove obstruction
Sticking throttle/restricted movement Lubricate or replace
Overheating Allow to cool; determine cause
Sticking valves Repair per instructions in manufacturer’s manual
Broken, worn, or sticking piston rings Repair per instructions in manufacturer’s manual
Broken valve spring Repair per instructions in manufacturer’s manual
Bad spark plugs Install new spark plugs