Fuel Metering System
The fuel metering system is made up of the following parts:
| • | Fuel supply components (fuel tank, pump, filter, regulator and lines) |
| • | The fuel pump electrical circuit |
| • | The fuel rail assembly, including: |
| • | The throttle body assembly, including: |
| - | The idle air control (IAC) valve |
| - | The throttle position (TP) sensor |
Fuel Pump Electrical Circuit
When the ignition is first turned to the ON position, without the engine running,
the PCM turns the fuel pump relay ON for 2-3 seconds. This builds up
fuel pressure quickly. If the engine is not started within 2 seconds, the PCM
shuts the fuel pump OFF and waits until CKP reference pulses from the EI module are
present. As soon as the engine is cranked, the PCM turns the relay ON which powers
the fuel pump.
