Toro Lawn-boy - User Manual

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R-TEK/DURAFORCE (E) ENGINE SERVICE MANUAL

Table of Contents – Page 1 of 1

PREFACE

SAFETY

SPECIFICATIONS

SPECIAL TOOLS

TROUBLESHOOTING

MAINTENANCE

CARBURETOR

FUEL SYSTEM

IGNITION SYSTEM

REWIND STARTER

ENGINE

PIVOTING ZONE START BRAKE

ELECTRIC START SYSTEM (120 VOLT)

ELECTRIC START SYSTEM (12 VOLT)

Table of Contents

Questions and Answers:

C
costaelizabethAug 22, 2025
Why does my Toro Lawn-boy keep stalling?
- H
  hriveraAug 22, 2025
  If your Toro Engine stalls, it could be due to several reasons. First, make sure the engine isn't out of fuel and that you're using the correct fuel mixture. Other potential causes include a plugged fuel filter (clean it), a fouled spark plug (consult the “Spark Plug Fouled” table), or a plugged fuel cap vent (replace the fuel cap). Also, check for an inadvertently grounded ignition (inspect and repair), a plugged carburetor vent (clear the obstruction), or an overheated engine (clear debris from fins). Finally, improper lubrication can also cause stalling, so inspect for damage.
T
treynoldsAug 25, 2025
How to troubleshoot a Toro Lawn-boy that will not produce spark?
- A
  Amber LambAug 25, 2025
  If your Toro Engine isn't producing a spark, start by checking the spark plug wire to ensure it's properly connected. If it is disconnected, reconnect it. If the spark plug is fouled or damaged, replace it. A damaged spark plug wire may also be the cause, in which case you should replace the CD pack. Additionally, check for a coil kill wire that may be grounded and eliminate any unwanted grounds. If the ignition coil has failed, replace the CD pack. Weak flywheel magnets can also be a factor, requiring replacement of the flywheel.
C
Christina RangelAug 26, 2025
What to do if my Toro Lawn-boy is flooded with fuel?
- M
  Martin LewisAug 27, 2025
  If your Toro Engine is flooded with fuel, it might be due to overuse of the choke position; take the throttle off choke. If your engine has a throttle cable, it might be misadjusted, so adjust it. A plugged air cleaner can also cause flooding; wash and re-oil the air cleaner element if you have a DuraForce engine. A fouled spark plug can also contribute, so replace it. Additionally, check if the carburetor inlet needle is stuck open or leaking; if so, clean the carburetor, replace any failed parts, and pressure test it. Finally, ensure the carburetor air vent is clean.
A
audrey69Aug 28, 2025
Why does my Toro Engine lack power?
- S
  Stacy HurleyAug 28, 2025
  If your Toro Engine lacks power, several factors could be the cause. A dull blade (mower only) can reduce performance, so sharpen or replace it. A housing choked with grass and debris (mower only) can also be a factor, so thoroughly clean the housing. Other potential issues include a plugged exhaust system (clean exhaust ports), a plugged muffler (clean or replace it), or a sheared flywheel key (replace it). A dirty carburetor can also cause power loss, so clean it. Additionally, check for an intake air leak and repair or replace any failed components. Finally, low compression can also result in reduced power; consult the “Engine Has Low Compression” table.
L
Levi WilsonAug 29, 2025
What causes a Toro Lawn-boy Engine to overheat?
- M
  melissa10Aug 29, 2025
  If your Toro Engine is overheating, start by checking the cylinder head cooling fins for clogs and clean them thoroughly. Restricted carburetor jets can also cause overheating, so clean the carburetor and jet. Ensure that the gas to oil mix ratio is correct. Also, make sure the cooling air intake isn't plugged; remove any foreign material and clean it.
C
Charles MarshallAug 31, 2025
Why does my Toro Lawn-boy start cold but not hot?
- S
  steveblevinsAug 31, 2025
  If your Toro Engine starts when cold but not when hot, the engine may be flooded; refer to the “Engine Flooded With Fuel” table. Excessive alcohol in the fuel could also be the problem; use no more than a 10% ethanol blend and avoid methanol. The engine may also be overheating; refer to the “Engine Overheats” table. A clogged bowl vent can also cause this issue; clean the bowl vent. Finally, fuel percolation (vapor lock) might be occurring; use current season gas for the fuel mixture.
W
William BurtonSep 2, 2025
What causes a Toro Engine to backfire?
- A
  Alicia WilliamsSep 2, 2025
  If your Toro Engine is backfiring, a sheared flywheel key could be the cause; replace the key. A muffler filled with carbon can also lead to backfiring; clean the muffler. Additionally, check for plugged exhaust ports and clean them. An air leak to the crankcase can also cause backfiring; replace the seals or re-seal the crankcase to the cylinder. Lastly, a partly fouled spark plug can contribute to backfiring; clean or replace it.
B
Brandon BarreraSep 4, 2025
Why is my Toro Lawn-boy surging?
- K
  kwatsonSep 4, 2025
  If your Toro Engine surges, a fouled idle circuit could be the cause; clean the idle circuit. An air leak can also lead to surging; check sealing surfaces, oil seals, gaskets, and port plugs. Restricted fuel flow can also be a factor; check the filters and fuel line. If the engine RPM is low, adjust it to the proper specification (note: a slight surge at no load is normal). For R tek engines, a misadjusted governor link can cause surging; adjust it. Finally, a sticking air vane can contribute to surging; clean or replace it.
E
Emily TownsendSep 7, 2025
What causes low compression in a Toro Lawn-boy Engine?
- J
  jennifer52Sep 7, 2025
  If your Toro Engine has low compression, it could be due to worn piston rings, in which case you should replace the piston rings or short block. Another cause could be piston ring(s) stuck in the groove, so replace the piston and rings. A worn cylinder can also lead to low compression, so remove and replace the short block.
A
Anthony McgrathSep 9, 2025
Why is my Toro Lawn-boy Engine vibrating excessively?
- J
  John BaileySep 9, 2025
  If your Toro Engine is vibrating excessively, the blade might be out of balance; balance it or replace it if damaged. A bent blade can also cause vibration; replace the blade. Loose engine mounting screws can also contribute; tighten the engine mounting screws (engine to plate, plate to mower housing). A bent crankshaft can also cause vibration; replace the crankshaft. Finally, a flywheel that is out of balance or damaged can cause vibration; replace the flywheel.

Toro Lawn-boy Specifications

General

Brand	Toro
Model	Lawn-boy
Category	Engine
Language	English

Summary

SAFETY

SAFETY INFORMATION

Provides crucial safety warnings and instructions for engine service.

Safety Tips

Offers essential advice to prevent accidents and injuries during operation.

TROUBLESHOOTING

Engine Will Not Start When Cold

Common causes and remedies for an engine that won't start in cold conditions.

Engine Will Start When Cold, But Not When Hot

Troubleshooting steps for engines that fail to restart when warm.

Engine Lacks Power

Identifies causes and solutions for reduced engine power.

Engine Surges

Addresses issues causing inconsistent engine speed or RPM fluctuations.

Engine Backfires

Explains reasons for the engine firing incorrectly, causing backfiring.

Engine Flooded With Fuel

Troubleshooting steps when the engine has too much fuel.

Engine Has Low Compression

Diagnosing and fixing issues related to low cylinder compression.

Engine Overheats

Causes and remedies for the engine running too hot.

Engine Vibrates Excessively

Addresses causes of unusual or excessive engine vibration.

Engine Crankshaft Will Not Turn

Troubleshooting steps when the engine crankshaft is seized or won't rotate.

Engine Produces Mechanical Knocking Sound

Identifies sources of abnormal mechanical knocking noises from the engine.

Engine Pre-Ignites

Explains premature ignition issues and their solutions.

Engine Smokes Excessively (Smoke is light colored, engine runs well)

Diagnosing light-colored smoke indicating engine running well.

Engine Smokes Excessively (Smoke is dark, engine runs poorly)

Troubleshooting dark smoke indicating poor engine performance.

Engine Stalls

Addresses common reasons for the engine stopping unexpectedly.

Spark Plug Fouled

Troubleshooting issues related to a fouled spark plug.

CARBURETOR

Engine Starts Hard

Troubleshooting steps for a carburetor that makes starting difficult.

Engine Runs Rich

Diagnosing and fixing issues causing the engine to run rich.

Engine Runs Lean

Troubleshooting causes for an engine running too lean.

Fuel Leaks From Carburetor

Addresses fuel leaks originating from the carburetor.

Fuel Leaks From Carburetor (Leaking starts after running, stops after shutdown)

Troubleshooting 'spit-back' fuel leaks from the carburetor.

IGNITION SYSTEM

ENGINE

ELECTRIC START SYSTEM (120 VOLT)

ELECTRIC START SYSTEM (12 VOLT)

Troubleshooting

Diagnosing and correcting problems with the 12V electric start system.

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