To determine if insufficient fuel flow is causing rough running or stalling, do the following steps:
1. Perform a fuel flow test.
2. Analyze the fuel flow test results.
[a] If the fuel rate is 246 L/hr (65 gal/hr) or more, no further troubleshooting is required;
refer to section 11.4.
[b] If the fuel rate is less than 246 L/hr (65 gal/hr), resolve the insufficient fuel flow;
refer to section 11.3.1.
11.3.1
Insufficient Fuel Flow Resolution
Perform the following steps to resolve the insufficient fuel flow:
1. Replace the fuel filter(s); refer to appropriate service manual, fuel system chapter.
NOTE:
Always fill the filter(s) with clean fuel before installing. Turn the filter(s) until they contact the gasket fully. Then, turn them an additional two-thirds by hand.
2. Inspect the fuel lines for restrictions due to pinching, kinking or other damage. If damage is found, repair as necessary; refer to OEM guidelines.
3. Inspect the cylinder head for a correct restricted fitting. If an incorrect fitting is found,
replace with a new fitting; refer to appropriate service manual, engine chapter.
4. Inspect the fuel return check valve for restrictive movement; refer to appropriate service
manual, fuel system chapter.
5. Inspect the fuel pump drive assembly. If damage is found, repair as necessary; refer to
appropriate service manual, fuel system chapter.
6. Verify repairs done to correct insufficient fuel flow; refer to section 11.3.1.1.
11.3.1.1
Test the Engine with Resolved Fuel Flow
Perform the following steps to determine if the fuel flow resolution resolved rough running
or stalling:
1. Start and run the engine.
2. Run the engine at idle with a no-load for approximately 5 minutes, allowing the engine
coolant to reach normal operating range, 88-96°C (190-210°F).
[a] If the engine is not running rough or stalling, no further troubleshooting is required.
Shut down the engine.
[b] If the engine is running rough or stalling, shut down the engine. Check for high fuel
temperature return; refer to section 11.4.
