Fuel injection enables the fuel/air ratio to be controlled very accurately, which contributes towards high power, low fuel consumption, smooth running and low exhaust gas emissions under a wide variety of motoring conditions. Fuel injectionSaab uses two different types of injection systems on their fuel injected engines. The 900 series engines with 8 valves per cylinder use a mechanical system, while the 16 valves engines have an electronic injector system. | 1. Fuel tank
2. Fuel pump
3. Pressure accumulator
4. Fuel filter
5. Fuel distributor
6. Control piston | 7. Measuring disc
8. Throttle plate
9. Injection valve
10.Cold-staring valve
11.Thermostatic switch
12.Pressure control regulator |  The injection valves are mounted in the inlet manifold at the cylinder head and inject continuously fuel upstreams the inlet valves. |  The fuel injection system senses the amount of air being drawn into the engine and ensures that it is injected with the correct quantity of fuel. |
Mechanical fuel injection system Fuel is pumped to the fuel distributor which is the brain of the system. The distributor senses the amount of air being drawn into the engine and then distributes proportional quantities of fuel to the injection valves. Inside the fuel distributor is a control piston (6), the position of which is regulated by the arm supporting the measuring disc (7) in the air intake. The measuring disc moves up and down and adopts a position that is determined by the speed of the engine and the position of the air damper (8). The greater the flow of air, the higher the measuring disc and thus the control piston will be lifted. The control piston has four vertical slots, one for each engine cylinder. As the control piston is lifted, the slots are gradually exposed, allowing a greater quantity of fuel to flow to the springloaded injection valves - one for each cylinder. The fuel is injected continuously, once the fuel pressure is high enough. When the engine stops, the pressure in the system falls and the valve closes again. | 
