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.
[a] If the return fuel temperature is less than or equal to 54°C (130°F), check for air
cleaner restriction; refer to section 12.6.
[b] If the return fuel temperature is greater than 54°C (130°F), resolve the high fuel
temperature return condition; refer to 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
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 section 188.8.131.52.
Test the Engine with Resolved High Fuel Temperature
Perform the following steps to determine if high fuel temperature repairs resolved lack of power
1. Start and run the engine.
2. Test drive the vehicle to ensure lack of power has been resolved.
[a] If lack of power did not occur during the test drive, no further troubleshooting is
required. Shut down the engine.
[b] If lack of power occurred during the test drive, shut down the engine. Check for a
restricted air cleaner element; refer to section 12.6.