CAUSE

SOLUTION

REPAIR DETAILS

No fuel

Put fuel in fuel tank

Bad fuel

Drain fuel tank and carburetor and refill

No fuel delivery

Inspect fuel lines, carburetor and fuel pump

*

Choke \ primer faulty

Adjust choke or replace primer

*

Faulty ignition

Repair ignition system

*

Plugged air filter

Replace air filter

Low compression

Repair engine

*

Low cranking speed

Charge \ replace battery or repair electrical system

*

Improper timing

Correct ignition timing

*

CAUSE

SOLUTION

REPAIR DETAILS

Bad fuel

Drain fuel tank and carburetor and refill

Faulty ignition

Repair ignition system

*

Plugged air filter

Replace air filter

Low compression

Repair engine

*

Low cranking speed

Charge \ replace battery or repair electrical system

*

Improper timing

Correct ignition timing

*

CAUSE

SOLUTION

REPAIR DETAILS

Improper timing

Correct ignition timing

*

Cutting blade removed

Install cutting blade

Common on push mowers

Faulty compression release

Repair compression release

CAUSE

SOLUTION

REPAIR DETAILS

Bad fuel

Drain fuel tank and carburetor and refill

Air leak

Reseal carburetor mounting

Fuel vent plugged

Clean / replace fuel cap

Main jet partially plugged

Clean carburetor

*

CAUSE

SOLUTION

REPAIR DETAILS

Vapor Lock

Reroute fuel line

*

Defective ignition components

Repair ignition system

*

CAUSE

SOLUTION

REPAIR DETAILS

Dirty air filter

Change air filter

Weak spark

Repair Ignition system

*

Fouled Spark plug

Change spark plug

Improper fuel mixture

Correct fuel mixture

*

Improper valve sealing

Adjust or reseal valves

*

CAUSE

SOLUTION

REPAIR DETAILS

Dirty air filter

Change air filter

Weak spark

Repair Ignition system

*

Fouled Spark plug

Change spark plug

Improper fuel mixture

Correct fuel mixture

*

Improper valve sealing

Adjust or reseal valves

*

CAUSE

SOLUTION

REPAIR DETAILS

Engine oil overfilled

Drain oil and refill correctly

Engine oil contaminated

Drain oil and refill correctly

Contaminated fuel

Drain fuel and carburetor

Faulty breather

Replace breather

Faulty head gasket

Replace head gasket

*

Worn valve guides

Replace valves and guides

*

Worn piston rings / cylinder

Replace piston and rings

*

CAUSE

SOLUTION

REPAIR DETAILS

Dirty air filter

Replace air filter

Fouled spark plug

Replace spark plug

Improper carburetor adjustment

Adjust carburetor

*

Improper choke adjustment

Adjust choke control

*

Weak ignition spark

Repair ignition system

*

CAUSE

SOLUTION

REPAIR DETAILS

Dirty air filter

Replace air filter

Contaminated fuel

Drain fuel and carburetor

Faulty ignition system

Repair ignition system

*

Improper carburetor adjustment

Adjust carburetor

*

Carburetor dirty

Clean carburetor

*

Malfunctioning governor

Adjust / repair governor

*

CAUSE

SOLUTION

REPAIR DETAILS

Improper throttle control adjustment

Make sure the throttle control moves smoothly throughout its entire range

Throttle linkage bent or stuck

Make sure the throttle linkage can move freely through its entire range

Throttle plate loose

Tighten the screws securing the throttle plate

Governor malfunctioning

Adjust / repair governor

*

CAUSE

SOLUTION

REPAIR DETAILS

Improper throttle control adjustment

Make sure the throttle control moves smoothly throughout its entire range

Governor malfunctioning

Adjust / repair governor

*

Improper fuel mixture

Clean and/or adjust carburetor

CAUSE

SOLUTION

REPAIR DETAILS

Improper carburetor adjustment

Clean and / or adjust carburetor

Engine in need of a tune up

Perform seasonal maintenance

*

Improper valve adjustment

Adjust valves

*

Carbon build up on piston

Clean carbon from piston

*

Exhaust system obstructed

Clear blockage from exhaust system

Internal components worn

Repair / replace mechanical components

*

CAUSE

SOLUTION

REPAIR DETAILS

Improper ignition timing

Set ignition timing

*

Improper valve clearance

Adjust valve clearance

*

Intake valve not seating

Reseat / replace intake valve

*

Lean fuel mixture

Adjust or reseal carburetor

*

CAUSE

SOLUTION

REPAIR DETAILS

Exhaust leak

Repair exhaust leaks

Bad spark plug

Replace spark plug

Exhaust valve not seating

Adjust / replace exhaust valve

*

CAUSE

SOLUTION

REPAIR DETAILS

Tune up needed

Perform seasonal maintenance

*

Improper carburetor adjustment

Adjust carburetor

*

Improper choke adjustment

Adjust / repair choke

*

Improper timing adjustment

Adjust timing

*

Mechanical restriction in engine

Correct the mechanical drag

*

Mechanical restriction of machine engine is running

Repair / replace the source of the mechanical resistance

Carburetor leaking fuel

Repair carburetor

*

External fuel leak

Repair tank, fuel lines, or connections as required

Fuel leaking past float needle

Repair carburetor

*

Fuel leaking at fuel pump diaphragm

Repair / replace fuel pump

*

CAUSE

SOLUTION

REPAIR DETAILS

Fuel leaking past float needle

Repair carburetor

*

Fuel leaking at fuel pump diaphragm

Repair / replace fuel pump

*

Fuel entering during transport

Shut off fuel before transport

CAUSE

SOLUTION

REPAIR DETAILS

Rich fuel mixture

Adjust carburetor

*

Engine running hot

See “engine runs too hot” section

Engine running too fast when shut off

Idle engine before shutting off ignition

CAUSE

SOLUTION

REPAIR DETAILS

Improper ignition timing

Set ignition timing

*

Engine overloaded

Make sure engine is of proper size for equipment and there are no mechanical restrictions

Plugged cooling fins

Remove engine shrouds and clean contamination from cooling fins

CAUSE

SOLUTION

REPAIR DETAILS

Defective gaskets or seals

Replace components as required

Excessive compression leakage

Diagnose and repair internal components

*

Engine oil overfilled

Drain and refill to proper level

*

Engine oil contaminated

Drain and refill to proper level

*

CAUSE

SOLUTION

REPAIR DETAILS

Bent or imbalanced equipment attached to engine

Replace blade or blade adaptor as required

*

Cylinder misfiring

See “cylinder misfiring” section

Damaged flywheel

Replace flywheel – DO NOT ATTEMPT TO REPAIR

*

Loose engine mounting bolts

Tighten engine mounting bolts

CAUSE

SOLUTION

REPAIR DETAILS

Ignition system faulty

Repair ignition system

*

Mechanical components worn or broken

Repair internal components

*

Leaking head gasket

Replace head gasket

*