Test Procedure
-- Perform a preliminary check to verify the customers complaint. Refer to PRELIMINARY CHECK
Fuel system is under pressure! Before opening the system, place rags around the connection area. Then release the pressure by carefully loosening the connection.
Start diagnosis
-- Disconnect fuel supply line and catch any fuel coming out with a shop towel. Refer to the Repair Information for location.
Pull circlip upward to unlock fuel line
-- Install a fuel pressure gauge with appropriate adapters.
-- Open shut off valve on fuel gauge.
-- Switch ignition on and off repeatedly until fuel pressure stops increasing pressure.
-- Read fuel pressure on the gauge.
- Specified value: 3.5 to 4.3 bar
- Turn the ignition switch OFF.
If specification is exceeded:
-- Check return line between fuel filter and fuel pump for kinks or blockage.
If no malfunction in fuel return line is found:
-- Pressure relief valve in fuel filter is malfunctioning.
-- Replace the fuel filter. Refer to the Repair Information.
If specified value was Not obtained:
-- Check fuel pressure at the fuel filter between fuel pump and fuel filter using appropriate adapters
-- Open shut off valve on gauge and start the engine. Allow to idle.
-- Slowly close the pressure gauge shut off and note the fuel pressure.
- Pressure must increase to 4 bar.
When 4 bar is reached: Open shut off tap immediately!
Turn the ignition switch OFF.
If pressure has increased during test:
-- Fuel pump is OK. Pressure relief valve in fuel filter is malfunctioning.
-- Replace the fuel filter. Refer to the Repair Information.
If pressure did not increase:
-- Fuel pump is faulty
-- Replace the fuel pump. Refer to the Repair Information.