Metro L4-079 1.3L VIN 2 MFI (2001)
Schematic
SYSTEM DESCRIPTION
The Powertrain Control Module (PCM) will energize the fuel pump relay for 2 seconds when the ignition switch is turned to the ON position. The
fuel pump will operate and pressurize the fuel system when the fuel pump relay is energized. The PCM receives ignition system reference pulses when
the engine is cranked or running. The PCM will continue to energize the fuel pump relay as long as the PCM receives ignition system reference pulses.
The PCM will de-energize the fuel pump relay when ignition system reference pulses are no longer detected.
The fuel pump delivers fuel to the fuel injectors in the fuel rail at a controlled pressure. The controlled pressure is 270-310 kPa (38.5-44 psi) when the
fuel pump is energized and the engine is not running. The controlled pressure is 200-240 kPa (28.5-34 psi) when the engine is idling at normal
operating temperatures. The fuel-pressure regulator maintains the correct fuel pressure at all times by returning excess fuel to the fuel tank.
DIAGNOSTIC AIDS
Incorrect fuel system pressure can result in any of the following conditions:
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The engine cranks but will not start.
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The engine cuts out or stalls. This may feel like an ignition malfunction.
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A decrease in fuel economy and a decrease in power.
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Hard starting
Check for water contamination of the fuel if the vehicle will not start in freezing weather. Ice can form in the fuel system and prevent the fuel from
reaching the fuel injectors at the necessary fuel pressure and at the necessary volume.
The normal fuel pump electrical resistance is 0.8-1.5 ohms at 20°C (68°F).
An intermittent malfunction may be caused by a fault in the fuel pump electrical circuit. Inspect the wiring harness and the components for any of the
following conditions:
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Backed out terminals.
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Incorrect mating of terminals.
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Broken electrical connector locks.
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Incorrectly formed terminals or damaged terminals.
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Any faulty terminal to wire connections.
