Kohler Command PRO ECH740

Margaret RowlandNov 23, 2025

Why is my Kohler Command PRO ECH740 Crankshaft engine hard to start?

S
Susan RasmussenNov 24, 2025
If your Kohler Crankshaft engine starts hard, several factors could be responsible. First, ensure the PTO drive is disengaged. Dirt or water in the fuel system can cause hard starting; check and replace the fuel if necessary. A clogged fuel line or fuel filter can also be the problem; clear or replace these components. Also, loose or faulty wires or connections can cause hard starting; secure them. Other potential causes include faulty or improperly adjusted throttle controls (adjust or replace them), faulty spark plugs (replace them), low compression (perform a compression test and repair), a weak spark (check ignition system and replace components), or a fuel pump malfunction. Additionally, an overheated engine due to restricted cooling or air circulation, improper fuel quality, a sheare...

Fuel System	Carburetor
Cooling System	Air-cooled
Compression Ratio	8.5:1
Starter	Electric
Ignition	Electronic
Fuel Type	Gasoline
Max RPM	3600 RPM
Governor Type	Mechanical
Lubrication System	Full Pressure
Crankshaft Type	Forged Steel
Crankshaft Orientation	Horizontal
Engine Type	4-cycle, OHV

Fuel System

Carburetor

Cooling System

Air-cooled

Compression Ratio

8.5:1

Starter

Electric

Ignition

Electronic

Fuel Type

Gasoline

Max RPM

3600 RPM

Governor Type

Mechanical

Lubrication System

Full Pressure

Crankshaft Type

Forged Steel

Crankshaft Orientation

Horizontal

Engine Type

4-cycle, OHV

Summary

Section 1 Safety and General Information

Safety Precautions

General safety guidelines for operating and maintaining the engine, including warnings and cautions.

Explosive Fuel!

Highlights the flammability of gasoline and precautions for handling and storage.

Lethal Exhaust Gases!

Details the dangers of carbon monoxide from exhaust fumes and safe operating practices.

Electrical Shock!

Warns about the risk of electrical shock from engine components while running.

High Pressure Fluid Puncture!

Caution regarding injuries from high-pressure fluid leaks in the fuel system.

Engine Identification Numbers

Explains how to locate and identify engine model and serial numbers.

Oil Recommendations

Specifies the correct oil type, viscosity, and API service class for engine lubrication.

Oil Type

Provides guidance on selecting the appropriate oil viscosity based on temperature.

Periodic Maintenance Instructions

Outlines routine maintenance tasks and their recommended frequencies.

Maintenance Schedule

Lists scheduled maintenance intervals for various engine components.

Storage

Provides instructions for proper engine storage procedures to prevent damage.

Section 2 Tools & Aids

Tools

Lists essential tools and their part numbers required for engine service.

Aids

Lists necessary aids, lubricants, and sealants for engine maintenance.

Special Tools You Can Make

Provides instructions for creating custom tools for specific engine service tasks.

Section 3 Troubleshooting

Troubleshooting Guide

A systematic guide to diagnosing common engine problems and their potential causes.

Engine Cranks But Will Not Start

Lists common causes and checks for an engine that cranks but fails to start.

Engine Starts Hard

Identifies potential issues when an engine is difficult to start.

Engine Overheats

Details common causes and checks for an engine that is overheating.

Crankcase Vacuum Test

Explains how to perform a crankcase vacuum test to diagnose engine issues.

Cylinder Leakdown Test

Describes the procedure for cylinder leakdown testing to assess component wear.

Section 4 Air Cleaner and Air Intake System

Heavy-Duty Air Cleaner

Details the components, service, and removal of the heavy-duty air cleaner system.

Low-Profile Air Cleaner (Optional)

Describes the optional low-profile air cleaner, its service, and components.

Air Intake;Cooling System

Ensures proper engine cooling by maintaining clean external surfaces and fins.

Section 5 Electronic Fuel Injection (EFI) System

EFI Fuel System Components

Lists and describes the principal components of the Electronic Fuel Injection system.

Operation

Explains how the EFI system manages fuel and ignition for optimal performance.

Electrical Components

Covers critical electrical components like ECU, sensors, and wiring harness.

Troubleshooting

Provides guidance for diagnosing and resolving EFI system issues.

Crankshaft Position Sensor

Details the function, service, and testing of the crankshaft position sensor.

Throttle Position Sensor (TPS)

Explains the TPS function, testing, and replacement procedure for EFI system operation.

ECU Reset and TPS Learn Procedure

Outlines the steps for resetting the ECU and performing the TPS learn procedure.

Oxygen Sensor

Describes the oxygen sensor's function, testing, and troubleshooting for EFI system tuning.

Fuel Injectors

Explains fuel injector operation, testing for electrical issues, dirt, or leakage.

Fuel Pump

Covers the electric fuel pump module and lift pump, including testing and replacement.

Throttle Body;Intake Manifold Assembly

Describes the throttle body's function and service, including idle speed adjustment.

Initial Governor Adjustment

Highlights the critical nature of governor adjustment for EFI engine performance.

Fault Codes

Lists and explains diagnostic fault codes generated by the EFI system.

Section 6 Lubrication System

Oil Recommendations

Specifies the correct oil type, viscosity, and API service class for engine lubrication.

Check Oil Level

Details the procedure for checking and maintaining the proper engine oil level.

Changing Oil and Oil Filter

Provides instructions for performing regular oil and oil filter changes.

Section 7 Electrical System and Components

Spark Plugs

Covers spark plug types, gap specifications, service, and inspection criteria.

Battery

Provides recommendations for battery size, maintenance, and testing procedures.

Battery Charging System

Explains the 20/25 amp regulated charging system and guidelines to avoid damage.

Electric Starting Motors

Covers starting motor operation, precautions, and removal/installation.

Solenoid Test Procedure

Provides detailed tests for the starter solenoid's pull-in coil and hold-in coil functions.

Section 8 Disassembly

Typical Disassembly Sequence

Suggests a systematic sequence for complete engine disassembly.

Shut Off Fuel Supply

Essential safety step to shut off fuel supply before proceeding with disassembly.

Drain Oil from Crankcase and Remove Oil Filter

Instructions for draining engine oil and removing the oil filter.

Remove Lift Fuel Pump and Fuel Pump Module

Steps for disconnecting and removing the lift fuel pump and fuel pump module.

Remove Throttle Body

Procedure for disconnecting sensors and removing the throttle body assembly.

Remove Fuel Injectors

Details the process for disconnecting electrical connectors and removing fuel injectors.

Remove Cylinder Heads and Hydraulic Lifters

Instructions for removing cylinder heads, push rods, and hydraulic lifters.

Remove Fan and Flywheel

Steps for safely removing the fan and flywheel from the crankshaft.

Remove Closure Plate Assembly

Procedure for removing the closure plate assembly from the crankcase.

Remove Camshaft

Instructions for removing the camshaft from the engine.

Remove Connecting Rods with Pistons and Rings

Steps for removing connecting rods, pistons, and rings from the cylinder bores.

Remove Crankshaft

Procedure for carefully removing the crankshaft from the crankcase.

Section 9 Inspection and Reconditioning

Camshaft

Inspection and service procedures for the camshaft, including gear teeth and lobe wear.

Crankshaft

Inspection and service for crankshaft gear teeth, bearing surfaces, and keyways.

Crankcase

Inspection of gasket surfaces and cylinder bore for wear or damage.

Pistons and Rings

Inspection of pistons and rings for damage such as scoring, sticking, or detonation.

Connecting Rods

Inspection of connecting rod bearing areas for wear and clearance.

Section 10 Reassembly

Typical Reassembly Sequence

Provides a suggested order for reassembling engine components after service.

Install Crankshaft

Instructions for lubricating and installing the crankshaft into the crankcase.

Install Connecting Rods with Pistons and Rings

Steps for installing piston assemblies, including ring staggering and lubrication.

Install Camshaft

Procedure for lubricating and installing the camshaft with timing marks aligned.

Thrust Bearing, Washer and Shim

Details the installation and adjustment of crankshaft end play components.

Install Closure Plate Assembly

Instructions for installing the closure plate assembly with sealant and checking end play.

Install Flywheel

Procedure for cleaning, aligning, and installing the flywheel onto the crankshaft.

Install Hydraulic Lifters and Cylinder Heads

Steps for installing hydraulic lifters and cylinder heads, ensuring proper alignment.

Install Push Rods and Rocker Arms

Procedure for installing push rods and rocker arms, ensuring correct positioning and lubrication.

Install Spark Plugs

Instructions for installing new spark plugs and torquing them to specification.

Install Intake Manifold

Steps for installing the intake manifold with new gaskets and torquing fasteners correctly.

Install Fuel Injectors

Procedure for installing fuel injectors, ensuring proper O-ring lubrication and retaining clip use.

Install Throttle Body

Instructions for installing the throttle body assembly, including sensors and linkage.

Install Lift Fuel Pump and Fuel Pump Module

Steps for installing the lift fuel pump and fuel pump module with associated lines.

Setting Initial Governor Adjustment

Critical procedure for setting the governor to ensure proper engine speed control.

Install Oil Filter and Fill Crankcase with Oil

Procedure for installing the oil filter, filling the crankcase with oil, and checking the level.

Prepare the Engine for Operation

Final checks before starting the engine, including tightening hardware and checking fluid levels.

Testing the Engine

Recommends operating the engine on a test stand to check for leaks and proper function.

Kohler Command PRO ECH740 - User Manual

Table of Contents

Questions and Answers