Vanguard BIG BLOCK M540000, Repair Manual, Page: 33 / 168

Gasoline-Fueled Engine Troubleshooting Chart
Gasoline-Fueled Engine Troubleshooting Chart
Problem Potential Cause Action
Perform On-Board Diagnostics
(OBD) test (EFI engines)
See applicable EFI Diagnostic and
Repair manual for your engine
Choke partially closed (carbureted engines) Open choke fully
Carburetor out of adjustment Service carburetor. See SECTION 6 - SERVICE
ENGINE SUBASSEMBLIES - Carburetor
Ignition improperly timed Check crankshaft/flywheel key for
wear or damage. See SECTION 6 -
SERVICE ENGINE SUBASSEMBLIES -
Flywheel, Crankshaft, Crankcase Cover
Low compression Check engine compression
components. See Check Compression
ComponentsCheck Compression Component
Low oil level Check engine oil level. See SECTION
2 - MAINTENANCE - Check Engine Oil
Air cleaner clogged or air intake restriction Clean or replace air filter. See SECTION 2
- MAINTENANCE - Clean/Replace Air Filter
Water or other contamination in fuel Drain tank, fuel system, and fuel
lines; replace with recommended fuel.
Low fuel pressure (EFI engines) Verify that fuel pressure is between 38 - 41
PSI (262 - 296 kPa). See applicable EFI
Diagnostic and Repair manual for your engine
Exhaust system restriction Clean exhaust ports; remove
and clean or replace muffler
Engine lacks power
Engine load too great Check equipment for damaged components,
worn bearings or debris buildup
Exhaust system leak Check exhaust manifold, muffler and all
gaskets for leaks. Replace as necessary
Engine does not run smoothly See "Engine surges, will not hold steady speed"
Loose or worn equipment; such as mower
blades, pulleys, gears, clutches, drive belts, etc.
Inspect and repair any equipment components
that may be loose, worn or damaged
Worn cylinder Inspect cylinder for wear. See SECTION
6 - SERVICE ENGINE SUBASSEMBLIES
- Crankcase and Crankcase Cove
Worn or loose connecting rod or crankshaft Inspect and replace worn or damaged
components. See SECTION 6 - SERVICE
ENGINE SUBASSEMBLIES - Connecting Rod
Bent crankshaft Replace crankshaft. See SECTION 6 -
SERVICE ENGINE SUBASSEMBLIES -
Flywheel, Crankshaft, Crankcase Cover
Loose flywheel Tighten flywheel nut. See SECTION 6 -
SERVICE ENGINE SUBASSEMBLIES -
Flywheel, Crankshaft, Crankcase Cover
Flywheel fan blades broken Replace flywheel fan. See
SECTION 5 - DISASSEMBLE
ENGINE - Bottom End Disassembly
Ignition improperly timed Check crankshaft/flywheel key for
wear or damage. See SECTION 6 -
SERVICE ENGINE SUBASSEMBLIES -
Flywheel, Crankshaft, Crankcase Cover
Loose external components Visually inspect engine and equipment for loose
components, air guides, shields and fasteners
Engine rattles, knocks or is noisy
Engine loose on equipment mounting Tighten mounting fasteners to correct specificati
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