Shindaiwa 81645 User Manual

15

Troubleshooting Guide

Does the engine crank?

Faulty recoil starter. 

Fluid in the crankcase. 

Internal damage. 

Consult with an authorized servicing dealer. 

Consult with an authorized servicing dealer. 

Consult with an authorized servicing dealer. 

NO

Good compression?

Loose spark plug.

Excess wear on cylinder, piston, rings.

Tighten and re-test. 

NO

YES

Does the tank contain 

fresh fuel of the proper 

grade?

Refill with fresh, clean unleaded gasoline with

a pump octane of 87 or higher mixed with

a 2-cycle air cooled mixing oil that meets or

exceeds ISO-L-EGD and/or JASO FC classified

oils at 50:1 gasoline/oil ratio. 

Fuel incorrect, stale or contaminated;

mixture incorrect. 

NO

YES

Is fuel visible and moving 

in the return line when 

priming?

Check for clogged fuel filter and/or vent. 

Priming pump not functioning properly. 

Replace fuel filter or vent as required; restart. 

Consult with an authorized servicing dealer. 

NO

Is there spark at the spark 

plug wire terminal?

The ignition switch is in “O” (OFF)

position.

Shorted ignition ground. 

Faulty ignition unit. 

Move switch to “I” (ON) position and restart. 

NO

YES

YES

Check the spark plug.

If the plug is wet, excess fuel may be in

the cylinder. 

The plug is fouled or improperly gapped. 

The plug is damaged internally or of the 

wrong size. 

Crank the engine with the plug removed, 

reinstall the plug, and restart.

Clean and regap the plug to 0.024 - 0.028

inch (0.6 - 0.7 mm). Restart.

Replace the plug with an NGK BPMR6A or 

equivalent resistor type spark plug of the 

correct heat range. Set spark plug electrode 

gap to 0.024-0.028 inch (0.6-0.7 mm).

YES

What To Check 

Possible Cause 

Remedy

Is the engine overheating? 

Operator is overworking the unit. 

Carburetor mixture is too lean. 

Improper fuel ratio. 

Fan, fan cover, cylinder fins dirty  

or damaged. 

Carbon deposits on the piston or in

the muffler. 

Cut at a slower rate. 

Consult with an authorized servicing dealer. 

Refill with fresh, clean unleaded gasoline with

a pump octane of 87 or higher mixed with

a 2-cycle air cooled mixing oil that meets or

exceeds ISO-L-EGD and/or JASO FC classified

oils at 50:1 gasoline/oil ratio. 

Clean, repair or replace as necessary. 

Consult with an authorized servicing dealer. 

What To Check 

Possible Cause 

Remedy

Engine is rough at all

speeds. May also have 

black smoke and/or

unburned fuel at the 

exhaust.

Clogged air cleaner element.

Loose or damaged spark plug.

Air leakage or clogged fuel line.

Water in the fuel.

Piston seizure.

Faulty carburetor and/or diaphragm.

Service the air cleaner element.

Tighten or replace.

Repair or replace filter and/or fuel line.

Replace the fuel. See page 7.

Consult with an authorized servicing dealer.

Engine is knocking.

Overheating condition.

Improper fuel.

Carbon deposits in the combustion 

chamber.

See above.

Check fuel octane rating; check for presence of

alcohol in the fuel (pg. 7). Refuel as necessary.

Consult with an authorized servicing dealer.