GOVERNOR AND FUEL INJECTION PUMP 7N3873 - Caterpillar

Probable Causes
Cranking speed
Batteries
Voltage
Fuel quality
Starting aids (if equipped)
Parameters
Gear trainRecommended Actions
Table 1
Troubleshooting Test Steps Values Results
1. Check for Slow Cranking Speed
A. Connect Cat® Electronic Technician (ET) to the service tool connector.
B. Use Cat ET to monitor the following while cranking the engine:
- Engine speed
Note: If the engine cranks too slowly, the engine will not start.
C. Check for the following problems:
- Low voltage for an electric starting system
- Low air pressure for an air start system
- Excess parasitic load
- Engagement of a single starting motor on a dual starting motor system
Cranking Speed
Result: The engine speed is greater than 100 rpm for a duration of four revolutions.
Proceed to Test Step 2.
Result: The engine speed is not greater than 100 rpm for a duration of four revolutions.
Repair: Repair or replace damaged components.
If the problem is not resolved, proceed to Test Step 2.
2. Inspect the Batteries
A. Charge the batteries, if necessary. Refer to Special Instruction, SEHS7633, "Battery Test Procedure" for additional information.
B. Load-test the batteries. Refer to Special Instruction, SEHS9249, "Use of 4C-4911 Battery Load Tester for 6, 8 V and 12 V Lead Acid Batteries" for additional information.
Batteries
Result: The batteries are OK.
Proceed to Test Step 3.
Result: The batteries are NOT OK.
Repair: Repair or replace the batteries.
If the problem is not resolved, proceed to Test Step 3.
3. Check the Keyswitch Power to the Electronic Control Module
A. Install a 7X-1708 Multimeter Probe (RED) and a 7X-1709 Multimeter Probe (BLACK) onto the test leads of a multimeter.
B. Check the voltage at the following ECM connector locations:
- P1-69 (−Battery) and terminal P1-70 (keyswitch)
C. Use a multimeter to measure the keyswitch power at the ECM while the engine is cranked.
D. Remove the multimeter probes from the engine.
18 V
Result: The keyswitch power is greater than 18 VDC.
Proceed to Test Step 4.
Result: The keyswitch power is less than 18 VDC.
Repair: Refer to Troubleshooting, "Electrical Power Supply - Test" for additional information.
If the problem is not resolved, proceed to Test Step 4.
4. Check the Supply Voltage at the ECM
A. Install a 7X-1708 Multimeter Probe (RED) and a 7X-1709 Multimeter Probe (BLACK) onto the test leads of a multimeter.
B. Check the battery supply voltage at the following ECM terminal locations during engine cranking:
- P1-48 (+Battery) and P1-61 (−Battery)
- P1-52 (+Battery) and P1-61 (−Battery)
- P1-53 (+Battery) and P1-61 (−Battery)
- P1-55 (+Battery) and P1-61 (−Battery)
- P1-57 (+Battery) and P1-61 (−Battery)
C. Remove the multimeter probes from the engine.
18 V
Result: The supply voltages are greater than 18 VDC.
Proceed to Test Step 5.
Result: The supply voltages are less than 18 VDC.
Repair: Refer to Troubleshooting, "Electrical Power Supply - Test" for additional information.
If the problem is not resolved, proceed to Test Step 5.
5. Check the Fuel Quality
A. Obtain a fuel analysis. The grade of the fuel affects the rate of fuel consumption. Refer to the engines Operation and Maintenance Manual for additional information.
B. Ensure that the fuel quality is not being affected by cold-weather conditions.
Fuel Quality
Result: The fuel quality is OK.
Proceed to Test Step 6.
Result: The fuel quality is NOT OK.
Repair: Replace the