WS4 Fuel Pressure and Flow ( Petrol only)

6. Idling: Measure the fuel pressure with the engine idling: 250 Kpa

7. Maximum: With the engine idling, use the special tool to clamp the fuel return line.
    Pressure: 450 Kpa.

8. WOT: With the engine idling, disconnect and plug the vacuum line going to the fuel pressure regulator.
    Pressure: 325 Kpa

9. Residual: Turn off the engine and watch the fuel pressure for five minutes.
    Residual pressure: 275 Kpa

10. Flow: Hook up proper equipment to read fuel volume if necessary. Record flow gauge results of volume or how much pumped in 15 seconds: (normal results may be half litter in 15 seconds)
2.2 L/m = 2.2/4 per 15seconds = 0.55 per 15 seconds.

12. Explain why it is important to know a vehicle fuel pressure/flow?
It is important to know about the vehicle fuel pressure because low or high pressure may effect the engine performance. High pressure push more fuel in the injectors and makes the engine run rich and low pressure makes it run lean.
13. Describe the symptoms a vehicle would give with each case:

Low fuel pressure: The engine will run lean and the oxygen sensor will give send the signal to ECU to reduce the amount of air so makes the throttle more close  even there is high demand of air for engine performance

Low fuel flow: Low fuel reduce the pressure in the hose so the above situation is created there.
High fuel pressure: High pressure put more fuel in the injector so makes engine run rich and so oxygen sensor will sense that there is shortage of air and will send the signal to ECU to send more air in and hence effect engine performance

Faulty fuel pressure regulator: It may send the fuel at high pressure or at low pressure