3126B Petroleum Engine Caterpillar

Engine Cranks but Will Not Start

Usage:

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The connection of any electrical equipment and the disconnection of any electrical equipment may cause an explosion hazard which may result in injury or death. Do not connect any electrical equipment or disconnect any electrical equipment in an explosive atmosphere.

Probable Causes

Electrical power to Electronic Control Module (ECM)
Personality module
Remote shutdown switch (if applicable)
Air shutoff circuit
Starting motor solenoid or starting circuit
Engine speed/timing sensors
Electrical connections to the electronic unit injector
Injection actuation pressure
Fuel supply
Combustion problem

Recommended Actions

Electrical power to ECM

Turn the keyswitch to the OFF position.

Check the positive battery and negative battery connections to the ECM.

Perform a pull test on positive battery wires and negative battery wires.

Check the negative battery connection to the engine ground.

Turn the keyswitch to the ON position.

The warning lamps should illuminate for five seconds.

If the warning lamp illuminates for five seconds, continue with this procedure.

If the warning lamp does not illuminate for five seconds, refer to Troubleshooting, "Electrical Power Supply Circuit - Test".

Personality Module

If a new ECM has been installed on the engine, the engine will not start. The ECM will not communicate with the Caterpillar Electronic Technician (ET) until the correct personality module (flash file) has been flashed into the ECM.

Check for a 253-02 Personality Module mismatch that is active or logged. If the code is active, update the personality module in the ECM. Refer to Troubleshooting, "Flash Programming".

Remote Shutdown Switch (If Equipped)

Access the Cat ET screen that displays the remote shutdown switch status. The remote shutdown switch status on the Cat ET is called "User Shutdown".

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Table 1
"User Shutdown Status"	Switch Status	Measured Voltage at P1-44 or P61-27
ON	Negative battery	<0.9 VDC
OFF	Open circuit	>10 VDC

If the voltage is not in the proper range, refer to Troubleshooting, "Remote Shutdown Switch Circuit - Test".

Air Shutoff Circuit

Refer to Troubleshooting, "Air Shutoff System - Test" for additional information.

Starting Motor Solenoid or Starting Circuit

Test the operation of the starting motor solenoid.

Check the engine wiring to the starting motor solenoid.

Test the operation of the starting motor.

Inspect the starter motor pinion and the flywheel ring gear for damage.

Engine Speed/Timing Sensors

Observe the engine speed on the Cat ET while the engine is being cranked.

This situation may require a direct hookup to the batteries in order to power the Cat ET while the engine is cranking. Refer to illustration 1 for the wiring diagram.

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Illustration 1	g00781203
Direct connection of Cat ET to the P1 connector

If the engine is cranking and Cat ET displays 0 rpm, a problem exists in the circuits for the engine speed/timing sensors. Refer to Troubleshooting, "Engine Speed/Timing Sensor Circuit - Test".

If an engine speed is present, check the sensor installation. If the sensor is not properly installed, the ECM may read engine speed, but the ECM cannot determine the tooth pattern. The ability for the ECM to read the tooth pattern is necessary to determine the cylinder position. Engine speed is present when engine speed is greater than 50 rpm. Refer to Troubleshooting, "Engine Speed/Timing Sensor Circuit - Test".

Electrical Connections to the Electronic Unit Injector

Ensure that the J300/P300 electronic unit injector connector is fully connected and free of corrosion.

Check for logged diagnostic codes that are related to the cylinder. Go to Troubleshooting, "Injector Solenoid Circuit - Test" if diagnostic codes that are related to the cylinder are present.

Check the Fuel Supply

Check the fuel level.

Monitor the exhaust for smoke while the engine is being cranked.
If no smoke is present, there may be a problem with the fuel quality or there may be a problem with the fuel supply.

Check the fuel pressure. Refer to Systems Operation/Testing and Adjusting, "Fuel System Pressure - Test".

Ensure that the fuel system has been primed. Refer to Systems Operation/Testing and Adjusting, "Fuel System - Prime".

Check for fuel supply lines that are restricted.

Check the fuel filters.

Cold weather adversely affects the characteristics of the fuel. Refer to Special Publication, SEBU6251, "Commercial Diesel Engine Fluids Reccomendations" for information on improving the characteristics of the fuel during cold weather operation.

Injection Actuation Pressure

Use Cat ET to check the injection actuation pressure.
1. Crank the engine and monitor the injection actuation pressure.
1. Monitor the output of the injection actuation pressure control valve.
  The high pressure oil system is operating properly if the pressure output is a minimum of 6 MPa (870 psi).

Check for a 164-11 injection actuation pressure system fault. If the diagnostic code has been logged recently, refer to Troubleshooting, "Injection Actuation Pressure Control Valve Circuit - Test".

If higher than actual pressure is being indicated, then disconnect the injection actuation pressure sensor and try to start the engine. If the engine starts, refer to Troubleshooting, "Injector Actuation Pressure Sensor -Test".