Fuel system
| 1 | EVAP canister | 5 | Pressure regulator at fuel tank |
| 2 | Evaporative emission system (EVAP) valve | 6 | Pressure regulator at fuel rail |
| 3 | Filler cap for fuel tank | 7 | Fuel rail |
| 4 | Fuel pump | 8 | Check valves |
S40/V40 uses a fuel system with return line, the purpose of which is to keep the fuel temperature below 50 °C (122 °F).
Two regulators are used to control pressure in the fuel rail:
- The return pressure regulator (5) is located beside the fuel tank. The fuel pressure at the outlet is kept at a value of 450 kPa (65.3 psi). The pressure regulator is of the spring type. The rest of the fuel is routed directly back to the fuel tank. To prevent fuel leaks (vapors) to the surroundings the valve is vented to the charcoal canister.
- The pressure regulator on the fuel rail (6) keeps a constant pressure to the injectors of 410 kPa (59.5 psi).
- This pressure regulator is dependent on the pressure in the inlet manifold.
Evaporative emission (EVAP) system
The hose between the canister and the fuel tank has a 1 mm (0.04 in) restriction, designed to prevent fuel in liquid form from reaching the canister when refuelling.
Draining of the canister is controlled by the EVAP-valve.
When there is boost pressure the canister is ventilated to the turbo's inlet side. If there is no boost pressure, the canister is ventilated to the inlet manifold.