Faulty Overflow Valve
To determine if a faulty overflow valve is causing a lack of power, perform the following steps:
- Run Fuel system Test #1: Downstream Pressure Test. Refer to "3.2 Test #1 Downstream Pressure Test" .
- If Test #1 indicates faulty overflow valve, proceed to step 3.
- Run fuel system Test #3: Flow Test – At Fuel Filter. Refer to "3.4 Test #3 Flow Test — At Fuel Filter" .
- If the overflow valve is found to be faulty, replace the overflow valve. Refer to "13.3.1 Overflow Valve Replacement" .
Overflow Valve Replacement
Perform the following steps to replace the overflow valve.
- Remove the overflow valve from the fuel return line.
- Install a new overflow valve. Tighten the valve to 48-52 N·m (35-38 lb·ft). See Figure
"Overflow Valve Location"
1. Unit Pump
4. Overflow Valve
2. Bypass to Fuel Return Port
5. Constant Ventilation (overflow)
3. Fuel Injector
Figure 1. Overflow Valve Location
- Verify overflow valve replacement; refer to "220.127.116.11 Test the Engine with Replaced Overflow Valve" .
Test the Engine with Replaced Overflow Valve
Perform the following steps to determine if the replaced overflow valve has 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.
- Start and run the engine.
- Run the engine at idle with a no-load condition for approximately five minutes, allowing the engine coolant to reach normal operating range.
- Test drive the vehicle to ensure lack of power has been resolved.
- If no lack of power occurred during the test drive, no further troubleshooting is required. Shut down the engine.
- If lack of power occurred during the test drive, shut down the engine. Check for high fuel temperature return; refer to "13.4 High Fuel Temperature Return" .
|EPA07 MBE 900 DDEC VI Troubleshooting Guide - 6SE580|
|Generated on 10-13-2008|