Section 12.5
High Fuel Temperature Return

To determine if high fuel temperature return is causing lack of power, perform the following steps: ‪

1. Test for high fuel temperature return.
2. Analyze the high fuel temperature test results.
   1. If the return fuel temperature is less than or equal to 54°C (130°F), check for air cleaner restriction; refer to "12.6 Restricted Air Cleaner Element" .
   2. If the return fuel temperature is greater than 54°C (130°F), resolve the high fuel temperature return condition; refer to "12.5.1 High Fuel Temperature Resolution" .

Section 12.5.1
High Fuel Temperature Resolution

Perform the following steps to resolve high fuel temperature return:‪

1. Remove and replace fuel filter(s); refer to Series 60 Service manual (6SE2007), fuel system chapter.
2. Inspect the combination check valve/regulator, replace if necessary; refer to Series 60 Service manual (6SE2007), fuel system chapter.
3. If equipped with a fuel cooler, refer to OEM for inspection guidelines.
4. Verify high fuel temperature repair; refer to "12.5.1.1 Test the Engine with Resolved High Fuel Temperature" .

Section 12.5.1.1
Test the Engine with Resolved High Fuel Temperature

Perform the following steps to determine if high fuel temperature repairs resolved lack of power condition: ‪

To avoid injury before starting and running the engine, ensure the vehicle is parked on a level surface, parking brake is set, and the wheels are blocked.‪

ENGINE EXHAUST ‪
To avoid injury from inhaling engine exhaust, always operate the engine in a well-ventilated area. Engine exhaust is toxic.‪

1. Start and run the engine.
2. Test drive the vehicle to ensure lack of power has been resolved.
   1. If lack of power did not occur during the test drive, no further troubleshooting is required. Shut down the engine.
   2. If lack of power occurred during the test drive, shut down the engine. Check for a restricted air cleaner element; refer to "12.6 Restricted Air Cleaner Element" .