Fuel pressure regulator

FUEL PRESSURE REGULATOR

This differential diaphragm device is set to a pressure of 3.00 ± 0.05 bar in the factory.

Pressurised fuel from the pump exercises thrust on reflux valve (7) countered by calibrated spring (8). When pressure setting is exceeded, reflux valve opens and excess fuel returns to the tank in order to stabilise pressure in the circuit. The vacuum in the intake manifold (acting also on injector nozzle ) acts on regulator diaphragm through intake (9) in order to reduce the load on the calibration spring.

The pressure differential between the fuel and the injector's surroundings (intake manifold) is therefore maintained constant under all engine service conditions. The injector flow (for a given supply voltage) thus depends solely on injection time established by the ECU.

NOTE The ECU assumes pressure as a fixed parameter. The regulator should never therefore be tampered with; otherwise the mixture concentration specified for the engine will be altered.

CARBON FILTER AND FUEL VAPOUR CUT-OFF VALVE

These components form part of the fuel evaporation control and vapour recovery system. They are located in the right wheel arch compartment and can be reached by removing the rear part of the right front wheel arch compartment trim.

1. Fuel vapour cut-off solenoid
2. Carbon filter

Carbon filter

This consists of carbon granules (4) that trap fuel vapour entering intake (5).

Warm flushing air enters intake (1), through paper filter (3) and flows over the carbon granules to remove fuel vapours and carry them toward the outlet (2) and then on toward the cut-off valve.

Air entering through intake (5) may also be pulled back by a vacuum in the tank, when it serves to ventilate the tank. Partition (6) ensures that the flushing air flows over all the carbon granules and promotes the release of fuel vapour toward the inlet manifold.

Two springs (7) allow the mass of granules to expand when the pressure increases.