2.2 - System Operation
When the ignition key is first turned to the ON position without starting the engine, a computer program runs the fuel pump for approximately 2 seconds to pressurize the system. This program will enhance cold and hot start-ups. When hot, this pressurization prevents vapour accumulation in the fuel line that can cause a hard start.
During cranking or with the engine running, the computer receives engine speed signals (RPM) that will turn the pump back on and will continuously run until the engine is turned OFF. When the engine is turned OFF, the pressure must be maintained for at least 10 minutes. This prevents long cranking caused by a longer system pressurization time.
Within milliseconds after the ignition key is turned to the ON position, the computer has already monitored inputs from as many as 20 sensors and switches to calculate the quantity of fuel required to efficiently run the engine.
But all of the above mentioned items depend on two basic elements: specific fuel pressure and volume from the fuel pump.