Running Loss System

Running Loss System:

The running loss system has the following features:
- a normally open pressure control valve is fitted at the lefthand side of the tank.
- two charcoal canisters are connected in series to reduce the concentration of fuel in vapour vented to atmosphere.
- a tank pressure sensor and canister close valve are fitted to allow the on-board diagnostic facility to test for leaks in the fuel and evaporative system.

The pressure control valve allows continuous venting of vapour to the charcoal canisters during normal running but prevents fuel entering the vent line during refueling. Fuel vapour from the tank passes through the valve to the lefthand canister and a third pipe connects the valve to the filler neck. When refueling, the difference in pressure between the tank interior and the open filler neck causes the valve to close, shutting off the vapour vent line. When the fuel cap is replaced, the pressures are equalised and the pressure control valve opens the vent line to the canisters.

The canister close valve is a solenoid operated device controlled by the ECM. The valve is normally open and is closed only during the leak test sequence.

The fuel pressure sensor is fitted to the evaporative loss flange and provides a voltage to the ECM which is proportional to tank vapour pressure.
Canister purge operation is as described in Evaporative Emissions Control System (EVAP).

Evaporative Flange Assembly:

The evaporative loss flange assembly is fitted to the top of the tank via a seal and locking ring. The assembly is removable complete with the fitted components.
The vapour vent / rollover valve and pressure sensor are a push fit via sealing grommets. The fuel pump connector is push fitted and crimped into a location tube on the underside of the flange.

Pressure Control Valve:

The pressure control valve is fastened by adhesive to the lefthand side of the tank. It is a non-serviceable component.

Canister, CCV and Fittings:

The canisters are fixed to the underside of the vehicle either directly or via semi-enclosed mounting brackets. Two fixing bolts are used at the front of the canister (or bracket) and a single rear bolt supports the canister and the canister close valve (CCV).
The vapour pipes to the canisters, other than the CCV, use multi-tang connectors which are push fitted and pulled out without the use of tools.
The canister close valve has a stub pipe with "O" ring seal which is a simple push fit into the canister. A mounting bracket on the canister close valve enables it to be secured to the underbody via the canister rear mounting bolt.
A hose connects the CCV to the bracket mounted adaptor into which the vent system air filter is screwed.