Pressure Ventilation Valve (Pvv); Naturally Aspirated Engine; Turbocharged Engines; First Filling Valve (Ffv) - Volvo B5254T3 Manual

Pressure Ventilation Valve (PVV)

The PVV works differently for naturally aspirated engines than turbocharged engines.

Naturally Aspirated Engine

On a naturally aspirated engine, pressure is limited to 400 kPa (corresponds to 380 kPa at the fuel rail).
The valve limits pressure surges occurring when the fuel injection is interrupted.
Pressure limitation is achieved by 'leaking' fuel through the valve. The fuel surplus runs into the
reservoir at approximately 34 I/h (applies only to naturally aspirated engines). The leakage also helps
to flush the valve free of particles.
When the engine is switched off, the valve maintains a residual pressure in the fuel injection system to
help prevent restarting problems.

Turbocharged Engines

The PVV is closed under normal driving conditions and only opens when there is a pressure surge in
the fuel rail (approximately 560 kPa). Examples of when pressure surges occur are when engine
braking and when the engine is switched off due to power loss.
The ECM raises the pressure in the system so the PVV opens (approximately 600 kPa). This flushes
the valve free of particles.
Pressure Relief Valve (PRV) Applies Only to B5244S4
The safety valve is integrated into the fuel pump. The valve opens in the range 550 kPa - 850 kPa.

First Filling Valve (FFV)

Allows fuel into the pump reservoir when the fuel tank is filled after it has been almost emptied.
The valve is closed when the car is tilted so that there is still fuel in the reservoir around the pump.
Check Valve
The valve closes when the pressure in the pump is lower than system pressure - when the engine and
power to the pump is switched off. This is to prevent the fuel line to the engine being drained of fuel.
The valve is integrated into the fuel pump.
Ejector
Continuously fills the pump housing with fuel.
Approximately 10-15 I/h is always flowing from the fuel pump through the ejector and back to the
reservoir.
Fuel Filter
The fuel filter is located in the reservoir and is integral with the pump/pickup assembly.