Section 11.3
Insufficient Fuel Flow

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.
   1. If the fuel rate is 246 L/hr (65 gal/hr) or more, no further troubleshooting is required; refer to "11.4 High Fuel Temperature Return" .
   2. If the fuel rate is less than 246 L/hr (65 gal/hr), resolve the insufficient fuel flow; refer to "11.3.1 Insufficient Fuel Flow Resolution" .

Section 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 "11.3.1.1 Test the Engine with Resolved Fuel Flow" .

Section 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: ‪

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. 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).
   1. If the engine is not running rough or stalling, no further troubleshooting is required. Shut down the engine.
   2. If the engine is running rough or stalling, shut down the engine. Check for high fuel temperature return; refer to "11.4 High Fuel Temperature Return" .