Checking the pressure in the engine power system

The main criterion for the health of the engine power system is the fuel pressure in the fuel rail.

With insufficient fuel pressure, the following are possible: – Unstable operation of the engine; – stop of the engine idling; – the raised or lowered frequency of rotation of a cranked shaft idling; - poor vehicle handling (engine does not develop full power); - jerks and dips in the engine when the car is moving.

To begin with, we recommend checking the reliability of the electrical contacts in the wiring harness blocks of the injection system units responsible for fuel supply (fuel pump, injectors).



Checking the fuel pressure in the fuel system is possible only if there is a pressure gauge with a hose for connection to the fuel line.

1. Turn on the ignition and listen: for a few seconds, the sound of the electric fuel pump should be heard. If it is not audible, check the pump power supply circuit.

WARNING: Be aware 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 serviceable electric fuel pump should have already created pressure in the system and its failure to turn on in this case is not a malfunction.

2. Reduce the pressure in the supply system (see Reducing the pressure in the engine supply system).



3. Compress the clamps of the fuel rail connector..



4.... and disconnect the fuel supply pipe from the fuel rail.

5. To check the fuel pressure, connect a pressure gauge (with a measurement limit of at least 5 kgf/cm²) between the fuel supply line and the fuel rail. With the engine idling, the pressure in the fuel line must be at least 365 kPa (3.65 kgf/cm²).

The following reasons for pressure drop are possible:

- Faulty fuel pressure regulator (depending on the type of engine, it is installed in the electric fuel pump or on the fuel rail);



– clogged fuel filters (installed in the electric fuel pump) or the electric fuel pump is faulty;




– the compensator of pulsations of pressure of fuel is faulty (mounted on the fuel rail of the 1.6L Duratec Ti-VCT engine).

Ways to eliminate these faults are described in the Removal, repair and installation of the fuel module subsection.