3500B Locomotive Engines Caterpillar

The probable root causes are listed in order below:

• Derated Engine

• Fuel Position Multiplier

• Personality Module

• Throttle Position Sensor signal

• Fuel Supply

• Air inlet or exhaust restriction

• Leaks in air system

• Faulty accessory equipment

Perform the following test in order:

1. Connect an Electronic Service Tool and check for logged derate events. A derate status flag will appear on the Electronic Service Tool if an active engine derate is occurring. The engine speed might be limited due to one of the following possible causes: altitude, exhaust temperatures that are high and air filters that are dirty.

2. Refer to Troubleshooting, "Fuel Position Multiplier".

3. Verify that the correct Personality Module is installed. Refer to Troubleshooting, "Programming Parameters".

4. Use the Electronic Service Tool in order to monitor the status of the throttle. Observe the throttle position. The throttle position should be stable. The throttle position should reach 100 percent. Refer to Troubleshooting, "Throttle Position Sensor".

5. Check fuel lines for the following problems: restrictions, collapse and pinched line. Repair the lines and/or replace the lines. Refer to the Testing and Adjusting, "Fuel System".

   1. Check the fuel tank for foreign objects which may block the fuel supply. Check for air in the low pressure fuel supply system after you perform the following procedures:
      • Replacing the fuel filters

      • Working on the low pressure fuel supply circuit

      • Replacing unit injectors

   2. Purge air from the low pressure fuel supply circuit with the hand priming pump and by cranking the engine in 30 second cycles. After you crank the engine, stop for two minutes. This will allow the starting motor to cool. Loosen the vent plug on the fuel return. The plug is located on the rear upper left side of the engine block. Hand prime the engine again if air in fuel continues. A sight glass in the low pressure supply line is helpful in diagnosing air in the fuel.

   3. Check fuel quality. In temperatures below 0 °C (32 °F), check for solidified fuel (wax). Refer to Special Instruction, SEBD0717, "Diesel Fuels And Your Engine". Check the fuel pressure with engine cranking. Check the fuel pressure at the filter. Refer to the Specifications Manual for correct pressure values. If pressure is low, check for plugged fuel filters. If the fuel pressure is still low check the following items: fuel transfer pump, fuel transfer pump coupling and fuel pressure regulating valve. Check for a combustion problem.

6. Check air inlet and exhaust systems for restrictions and/or leaks. Refer to the Testing and Adjusting, "Air Inlet And Exhaust System".

7. Observe the Check Engine Lamp. Check for an air filter restriction indicator. Replace plugged air filters and/or clean filters. Refer to the Testing and Adjusting, "Air Inlet and Exhaust System". Refer to Troubleshooting, "Engine Sensor Open/Short Test".

8. Check all accessory equipment.