Fuel system (petrol/gasoline)

The fuel system on the Saab 9-5 operates through an electric pump
situated in the fuel tank which draws fuel from the tank and builds up
pressure in the system. The pressure is determined by the pressure
regulator, which maintains the fuel pressure at a constant level
relative to the pressure in the engine intake manifold. Consequently,
the amount of fuel injected into the engine is determined only by the
opening duration of the injectors.


Fuel is injected into the engine by injectors (solenoid valves) mounted
in the intake manifold close to the inlet valves and connected by a
common fuel rail.

The opening times of the injectors are controlled by electrical impulses
from the control module. For a detailed description of the engine
management system in the Saab 9-5, refer to Group 2 “Engine management
system, Trionic 4-cyl.” .
The fuel pump is situated inside a plastic reservoir clamped between the
top and bottom of the tank. It is located by ribs on the bottom of the
tank and secured at the top by means of the pump cover (7). The pump is
fitted in the tank by screwing the screw ring (10) into the pump cover
from outside the tank. Any flexing of the tank is absorbed by the fuel
pump's spring element (9).


An ejector is "driven" by the flow of fuel through the delivery line via
a T-piece. The pump is an electric rotary pump. The purpose of the
ejector is to ensure that the pump is continuously supplied with fuel.
Due to the location of the pump in the reservoir, the supply of fuel to
the engine is maintained during cornering and acceleration even when
there is only a small quantity of fuel left in the tank.


The pump can be removed through a hole under the rear seat cushions.


A non-return check valve on the pressure side of the pump, fitted in the
connecting nipple on the pump cover, prevents the pressure in the fuel
line from dropping immediately after the engine has been switched off.
The non-return valve on the return side of the pump prevents fuel from
flowing "in reverse" should the car happen to overturn.


To reduce exhaust emissions when the engine is started, the fuel pump
has been modified for M01. The fuel pump unit has a check valve by the
ejector intake that ensures that the fuel level in the pump reservoir is
kept as high as possible, even when the level of fuel in the tank is
low. This means that the fuel pressure when the engine is started
increases more rapidly, providing better starting and thus reducing
exhaust emissions. There is a fine filter by the check valve intake
protecting it from dirt.

The fuel level sensor in the tank is mounted on the fuel pump plastic reservoir via a jointed arm.


The RFI filter helps to reduce the risk of radio interference in the system.
From the original1gatevalve
.