3512B and 3512C Petroleum Generator Set Engines Caterpillar

Engine Cranks but Does Not Start

Usage:

Probable Causes

Fuel
Active diagnostic codes
Slow Cranking Speed
Engine shutdown switches (if applicable)
Starting Aids (if applicable)
Air inlet and exhaust system
Theft deterrent system (if applicable)
Engine Speed/Timing
Fuel system
Injectors
Cylinder compression
Valve Lash

Recommended Actions

Use Caterpillar Electronic Technician (ET) to view the "No Start Parameters" group to view parameters related to engine starting.

Note: The procedures have been listed in order of probability. Complete the procedures in the order of the listed test steps.

Show/hide table

Table 1
Troubleshooting Test Steps	Values	Results
1. Fuel A. Visually check the fuel level in the fuel tank. Do not rely on the fuel gauge only. B. Ensure that the fuel supply valve (if equipped) is in the full OPEN position.	Fuel level	Result: The fuel level is OK. Proceed to Test Step 2. Result:The fuel level is not OK. Repair: Fill the tank. Verify that the repair eliminated the problem.
2. Check for Active Diagnostic Codes A. Establish communication between Cat ET and the Electronic Control Module (ECM). B. Monitor the diagnostic codes on Cat ET. Check for active diagnostic codes. Specifically check for codes related to the fuel system, the engine speed/timing sensors, and the fuel injectors. Note: Wait at least 30 seconds in order for diagnostic codes to become active.	Active Diagnostic Codes	Result: There are active codes. Repair: Troubleshoot any active codes before continuing with this procedure. Verify that the repair eliminated the problem. Result: There are no active codes. Proceed to Test Step 3.
3. Check for Slow Cranking Speed A. Check the cranking speed of the engine. 1. Use Cat ET to check the engine speed while cranking the engine. If the engine cranks too slowly, the engine will not start. 2. Check for the following problems: -Low voltage for an electric starting system -Excessive parasitic load -Engagement of a single starting motor on a dual starting motor system	Speed	Result: The engine speed is greater than 100 rpm for a duration of four revolutions. Proceed to the next step. Result: The engine speed is not greater than 100 rpm for a duration of four revolutions. Repair: Low voltage: -Charge and/or replace the batteries as necessary. Refer to Special Instruction, SEHS9249, "Use of 4C-4911 Battery Load Tester for 6V, 8V, and 12 V Lead Acid Batteries". Repair: Excessive parasitic load -Remove the parasitic load Repair: Starting Motor -Repair and/or replace the faulty starter as necessary.
4. Engine Shutdown Switches (if applicable) A. The engine shutdown switches must be in the OFF position.	Switches are in the OFF position	Result: The switches are in the OFF position. Proceed to Test Step 5. Result: The switches are not in the OFF position. Repair: Turn the switches to the OFF position. STOP. Verify that the repair eliminated the problem.
5. Starting Aids (if applicable) A. If cold ambient conditions exist, check the operation of the starting aids.	Starting aids are operational	Result: The starting aid is operating correctly. Proceed to Test Step 6. Result: The starting aid is not operating correctly. Repair: Refer to the appropriate diagnostic test in order to troubleshoot the starting aid. Verify that the repair eliminated the problem.
6. Restrictions in the Air Inlet and Exhaust System A. Check for an air filter restriction indicator (if applicable). B. Check the air inlet and exhaust system for restrictions and/or leaks.	Air and Exhaust System restrictions	Result: There are no system restrictions. Proceed to Test Step 7. Result: There are system restrictions. Repair: Refer to Systems Operation/Testing and Adjusting, "Air Inlet and Exhaust System" for additional information on the air inlet and exhaust systems. Replace plugged air filters. Refer to the Operation and Maintenance Manual for the correct procedure. Verify that the repair eliminated the problem.
7. Theft Deterrent System (if applicable) A. Verify that the theft deterrent system is not active.	Theft system is inactive.	Result: The theft deterrent system is not active. Proceed to Test Step 8. Result: The theft deterrent system is active. Repair: Turn the theft deterrent system OFF. Verify that the repair eliminated the problem.
8. Engine Speed/Timing A. Crank the engine and observe the engine speed on the Cat ET status screen. Refer to Troubleshooting, "Speed/Timing - Test" for additional information. B. Upon initial cranking, the status for engine speed may indicate that the engine speed signal is abnormal. This message will be replaced with an engine speed once the ECM is able to calculate a speed from the signal.	Timing signal	Result: The timing sensor is operating properly. Proceed to Test Step 9. Result: The timing sensor is not operating properly. Repair: Refer to Troubleshooting, "Speed/Timing - Test" for troubleshooting information. Verify that the repair eliminated the problem.
9. Fuel System A. Inspect the fuel system. Refer to Systems Operation/Testing and Adjusting, "Fuel System" for additional information. B. Cold weather adversely affects the characteristics of the fuel. Refer to the engines Operation and Maintenance Manual for information on improving the characteristics of the fuel during cold-weather operation. C. Check fuel quality. Refer to Systems Operation/Testing and Adjusting, "Fuel System" for the proper procedure. Check the fuel tank for debris or foreign objects which may block the fuel supply. D. Check the filtered fuel pressure while the engine is being cranked. Refer to Systems Operation/Testing and Adjusting, "Fuel System" for the test procedure and for the correct pressure values. If the fuel pressure is low, replace the fuel filters. Clean the primary filter/water separator of debris. Refer to the Operation and Maintenance Manual for details. E. Check for the proper operation of the fuel transfer pump. Refer to Systems Operation/Testing and Adjusting, "Fuel System" for test information.	Fuel system	Result: The fuel system is operating properly. Proceed to Test Step 10. Result: The fuel system is not operating properly. Repair: Make the necessary repairs. Verify that the repair eliminated the problem.
10. Injectors A. Use Cat ET to perform the "Injector Solenoid Test" to identify electrical problems in the fuel injection system.	Injector Solenoids	Result: Cat ET reports that all injector solenoids are OK. Proceed to Test Step 11. Result: Cat ET reports "Short" or "Open" for one or more injector solenoids. Repair: Refer to Troubleshooting, "Injector Solenoid - Test" for troubleshooting information. Verify that the repair eliminated the problem.
11. Low Cylinder Compression A. Perform a compression test on each cylinder.	Cylinder Compression	Result: At least one cylinder has been identified as having low compression. Repair: Identify the cause of the low compression. Possible causes of low compression include the following: - Faulty piston - Faulty piston rings - Worn cylinder bores - Worn valves - Faulty cylinder head gasket - Damaged cylinder head Perform the necessary repairs. Verify that the repair eliminated the problem. Result: The compression is OK for each cylinder. Proceed to Test Step 12.
12. Inspect the Valve Train and Check Valve Lash A. Inspect the valve train B. Check the valve lash	Valve Train	Result: The valve train is OK. There is no damaged parts or excessive wear. Valve lash is within specifications. Result: The valve train is not OK or there is excessive wear. Repair and/or replace as necessary. Repair: Perform the necessary repairs. Verify that the repair eliminated the problem. Result: The valve lash is not within the specifications. Repair: Adjust the valve lash as necessary refer to Testing and Adjusting, "Valve Lash and Valve Bridge Adjustment". Verify that the repair eliminated the problem.

If the procedure did not correct the issue, contact your Cat dealer Technical Communicator (TC). For further assistance, your TC can confer with the Dealer Solutions Network (DSN).