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Curtis B.
Curtis B., Technician
Category: Construction and Road Equipment
Satisfied Customers: 988
Experience:  Technican turned service manager with multiple lines of equipment and rental units.
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Cat Man Here Cat 321d sn# PNAS002977 it has a C6.4 Its hard

Customer Question

Cat Man mark Here Cat 321d sn# ***** it has a C6.4 Its hard start most of the time when cold i found a bad eng speed sensor NOTE this unit is equipment a PRE LUBE SYS I installed new speed sencor its still starting hard your thoughts
Submitted: 9 months ago.
Category: Construction and Road Equipment
Expert:  Cat Man replied 9 months ago.

Thanks for asking your question. I will try and help you out.

Unfortunately I am not fimiliar with that engine. Sorry. I will send to Donnie.

Customer: replied 9 months ago.
ok please send to him asap
Expert:  catmastertech replied 9 months ago.

Hello,

Are you concerned about the long cranking time before it starts or will it just not start when cold?

Expert:  catmastertech replied 9 months ago.

Could you also verify the serial number, that number is ***** listed.

Expert:  catmastertech replied 9 months ago.

Have any of the following been eliminated?

Probable Causes

  • Machine faults
  • Diagnostic codes and event codes
  • Electrical connectors
  • Air intake and exhaust system
  • Air inlet heater
  • Low-pressure fuel system
  • High-pressure fuel system
  • Cylinder performance

Do you CAT ET availible?

Customer: replied 9 months ago.
cat ET is avale the only one code was active was during cranking Was ENG speed sensor. i replaced and it deff made a diff but still has hard start when cold
Customer: replied 9 months ago.
did you get that ??
Customer: replied 9 months ago.
Donnie are you going to get back to me ??
Expert:  catmastertech replied 9 months ago.

I am sorry I missed your reply. I did not hear from you for such a long time, I thought you had found a different source.

I am assuming the machine has been inspected for damage or blockage to the air inlet and exhaust systems and the inlet heater is working correctly.

I would first verify the low pressure system is working correctly.

Then I would check the high pressure system for cranking speeds and rail pressures.

If pressures are low further testing is needed to isolate a possible leak or wear in the system.

See the notes below for details about testing.

NOTE: special tooling is needed to fully test the pump and injectors.

Troubleshooting

C4.2 and C6.4 Engines for Caterpillar Built Machines

Engine Cranks but Does Not Start

Probable Causes;

Machine faults

Diagnostic codes and event codes

Engine speed/timing

Electrical connectors

Air intake and exhaust system

Air inlet heater

Low-pressure fuel system

High-pressure fuel system

Cylinder performance

Recommended Actions

NOTICE

Do not crank the engine continuously for more than 30 seconds. Allow the starting motor to cool for two minutes before cranking the engine again.

Machine Faults

Make sure that the Machine Security System (if equipped) is not preventing the engine from starting.

Resolve any faults on the machine that could prevent the engine from starting.

Attempt to start the engine. If the engine will not start, proceed to "Diagnostic Codes and Event Codes".

Diagnostic Codes and Event Codes

Certain diagnostic codes and/or event codes may prevent the engine from starting. Connect Cat Electronic Technician (ET) and check for active codes and/or for logged codes. Troubleshoot any active codes that are present before continuing with this procedure.

Note: If there are any active diagnostic codes for the machine security system, verify that the lamp for the machine security system is illuminated. If the lamp for the machine security system is illuminated, the machine security system is armed. Deactivate the machine security system and try to start the engine.

Note: If a E390 Fuel Filter Restriction is logged and/or active, replace the fuel filters.

Fuel that does not meet the recommendations of Operation and Maintenance Manual, SEBU6250, "Caterpillar Machine Fluids Recommendations" may cause premature fuel filter restriction. If the fuel filters are restricted prior to normal service intervals, investigate the quality of the fuel. Use fuel that meets the recommendations of Operation and Maintenance Manual, SEBU6250, "Caterpillar Machine Fluids Recommendations".

Note: If a E198 Low Fuel Pressure is logged and/or active, refer to the symptom Troubleshooting, "Fuel Pressure Is Low".

Electrical Connectors

Check for correct installation of the J1/P1 and J2/P2 ECM connectors. Check for correct installation of all other applicable connectors. Refer to service Troubleshooting, "Electrical Connectors - Inspect".

Air Intake and Exhaust System

Check the air filter restriction indicator, if equipped. Clean plugged air filters or replace plugged air filters. Refer to the Operation and Maintenance Manual.

Check the air inlet and exhaust system for restrictions and/or leaks. Refer to Systems Operation/Testing and Adjusting.

Air Inlet Heater

Note: A faulty air inlet heater will only affect engine starting when the ambient temperature is below 10 °C (50 °F).

Check the operation of the air inlet heater. Refer to Systems Operation/Testing and Adjusting.

If necessary, replace the air inlet heater. Refer to Disassembly and Assembly.

Low Pressure Fuel System

Visually check the fuel level. Do not rely on the fuel gauge only. If necessary, add fuel. If the engine has been run out of fuel, purge the air from the fuel system. Prime the fuel system.

Ensure that the fuel supply valve (if equipped) is in the full OPEN position.

------ WARNING! ------

Contact with high pressure fuel may cause fluid penetration and burn hazards. High pressure fuel spray may cause a fire hazard. Failure to follow these inspection, maintenance and service instructions may cause personal injury or death.

----------------------

------ WARNING! ------

Do not loosen any high pressure fuel lines when the engine is running. The high pressure in the fuel lines can cause personal injury or death. Wait 60 seconds after the engine has stopped to allow pressure to purge before any service or repair is performed on the engine fuel lines.

----------------------

Check the fuel lines for the following problems: restrictions, collapsed lines, pinched lines and loose connections. If problems are found with the low-pressure fuel lines, repair the lines and/or replace the lines. If the high-pressure fuel lines have a leak, the high-pressure fuel lines must be replaced. Refer to the Disassembly and Assembly manual.

NOTICE

Do not crank the engine continuously for more than 30 seconds. Allow the starting motor to cool for two minutes before cranking the engine again.

Prime the fuel system if any of the following procedures have been performed:

Replacement of the fuel filters

Service on the low-pressure fuel supply circuit

Replacement of unit injectors

Note: A sight glass in the low-pressure supply line is helpful in diagnosing air in the fuel.

Check for air in the fuel system. Refer to Testing and Adjusting, "Air in Fuel - Test". Ensure that the fuel system has been primed. Attempt to start the engine. If the engine will not start, continue with this procedure.

Check the fuel tank for foreign objects which may block the fuel supply.

Check the fuel filters.

Check the diesel fuel for contamination. For acceptable quality, refer to Operation and Maintenance Manual, SEBU6250, "Caterpillar Machine Fluids Recommendations".

Cold weather adversely affects the characteristics of the fuel. Refer to the Operation and Maintenance Manual for information on improving the characteristics of the fuel during cold-weather operation.

Attempt to start the engine. If the engine will not start, continue with this procedure.

Check the flow of fuel through the transfer pump. If the flow is less than 250 mL (8.5 oz) per minute at 150 rpm, replace the pump. For instructions on removal and installation of the fuel transfer pump, refer to the engine Disassembly and Assembly manual. Make sure that the engine is primed. Attempt to start the engine. If the engine will not start, continue with this procedure.

High Pressure Fuel System

------ WARNING! ------

Escaping fluid under pressure, even a pinhole size leak, can penetrate body tissue, causing serious injury, and possible death. If fluid is injected into your skin, it must be treated immediately by a doctor familiar with this type of injury.

Always use a board or cardboard when checking for a leak.

------ WARNING! ------

Do not loosen any high pressure fuel lines when the engine is running. The high pressure in the fuel lines can cause personal injury or death. Wait 60 seconds after the engine has stopped to allow pressure to purge before any service or repair is performed on the engine fuel lines.

----------------------

Use Cat ET to check the absolute fuel rail pressure while the engine is cranking at a minimum speed of 150 rpm.

If the absolute fuel rail pressure is less than 25 MPa (3626 psi), perform the following procedure.

Check for fuel leaks in the high-pressure fuel system. Rectify any fuel leaks and then recheck the pressure in the fuel rail. If the absolute fuel rail pressure is greater than 25 MPa (3626 psi), proceed to Test Step 3.

Check that the inlet pressure at the fuel rail pump is greater than 50 kPa (7 psi). If the inlet pressure is less than 50 kPa (7 psi), repeat the diagnostic process from "Fuel Supply".

Use Cat ET to perform a solenoid test on the fuel rail pump. Refer to Troubleshooting, "Fuel Rail Pump - Test". Make repairs, as needed.

Attempt to start the engine. If the engine will not start, continue with this procedure.

Check the pressure relief valve in the fuel rail for leakage. If the pressure relief valve is leaking, replace the valve and recheck the pressure in the fuel rail.

If the pressure relief valve in the fuel rail is not leaking, check for fuel in the engine oil system. If fuel is suspected in the oil system, take an engine oil sample for analysis. Refer to the Operation and Maintenance Manual, "Engine Oil Sample - Obtain". If the analysis confirms that there is fuel in the engine oil system, investigate the cause.

If the absolute fuel rail pressure is less than 25 MPa (3625 psi), remove the outlet check valves from the pump. Clean the check valves and reinstall the check valves. Refer to Special Instruction, REHS5030, "Servicing the Outlet Check Plugs on the Fuel Injection Pump on C6.4 and C4.2 Engines".

If no fuel is found in the oil system and the outlet check valves are OK, check for excessive fuel leak off from the injectors. Refer to Special Instruction REHS3428, "Measuring Fuel Leakage Past the Fuel Injectors".

Note: The fault is not in the fuel rail pump. Do not replace the pump.

If the leak off is greater than the following quantity, replace the electronic unit injectors.

38 mL (1.3 oz) in 30 seconds for a 6 cylinder engine

25 mL (0.85 oz) in 30 seconds for a 4 cylinder engine

Note: Discard all fuel injection lines after use. Fuel injection lines must only be used one time.

If the leak off is less than the following quantity, proceed to Test Step 2.k.

38 mL (1.3 oz) in 30 seconds for a 6 cylinder engine

25 mL (0.85 oz) in 30 seconds for a 4 cylinder engine

Check the timing of the fuel rail pump. Refer to Testing and Adjusting, "Fuel Injection Timing - Check".

If the timing of the fuel rail pump required adjustment and the engine will not start, return to Test Step 1.

If the timing of the fuel rail pump was correct, replace the fuel rail pump. If the engine will not start, return to Test Step 1.

If the absolute fuel rail pressure is greater than 25 MPa (3626 psi), perform the following procedure.

Use Cat ET to make sure that the status of the electronic unit injectors is not "Disabled". If the injectors are disabled but not intentionally disabled with Cat ET, continue to Test Step 3.b.

If the electronic unit injectors are not disabled, use Cat ET to perform an injector solenoid test. Refer to Troubleshooting, "Injector Solenoid - Test".

If any service has been performed as a result of Step 3.b, attempt to start the engine. If the engine will not start, proceed to 3.d.

Contact the technical communicator at the Caterpillar dealer.

Note: This consultation can greatly reduce the repair time.

If the technical communicator recommends the use of a test ECM, install a test ECM. Refer to Troubleshooting, "Test ECM Mode".

If the engine starts normally, replace the ECM.

Cylinder Performance

Perform a compression test. Refer to Systems Operation/Testing and Adjusting. Possible causes of low compression are shown in the following list:

Faulty piston

Faulty piston rings

Worn cylinder bores

Worn valves

Faulty cylinder head gasket

Damaged cylinder head

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