Checking the engine fuel system (Mondeo 4)

The main indicator of the engine fuel system health is the fuel pressure in the fuel rail. But first, we recommend checking the condition of the air filter (see Replacing the Air Filter Element), as this is a simple procedure and does not take much time. After you make sure that the air filter is clean, check the reliability of the electrical contacts in the wiring harness pads of the injection system units responsible for fuel supply (electric fuel pump, injectors).



Checking the fuel pressure in the engine fuel rail is only possible if you have a pressure gauge with a set of adapters for connection to the fuel line.

1. Turn on the ignition and listen: within a few seconds you should hear the sound of the electric fuel pump. If you do not hear it, check the electric fuel pump power circuit.

WARNING: Keep in mind that the electric fuel pump will not turn on if there is pressure in the fuel supply system. In other words, if you previously turned on the ignition and tried to start the engine, then a working electric fuel pump should have created pressure in the system, so its failure to turn on in this case is not a malfunction.

2. The fuel pressure check procedure is described in Section 5 "Engine" (see Checking the pressure in the engine fuel system). When the engine is idling, the pressure in the fuel line should be about 3 kgf/cm².

The following are possible reasons for the decrease in pressure:



– the fuel pressure pulsation compensator is faulty (installed on 1.6 l VCT engines);



– the fuel pressure regulator is faulty (built into the fuel pump module);



– the fuel filter is clogged…





…integrated into the fuel pump module;



– the fuel pump is faulty (installed in the fuel pump module).

You will find methods for troubleshooting these problems in the Power System section.