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HOMESERVICE MANUALSCHEVROLET2008CHEVY EXPRESS G2500, VAN CARGO, 6.6 6REPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 24 (ENGINE CONTROLS - THEORY & OPERATION)FUEL SYSTEMSFUEL DELIVERYFUEL PUMP RELAY
2008 Chevrolet Chevy Express G2500, Van Cargo, 6.6 6

Fuel Pump Relay

2008 Chevrolet Chevy Express G2500, Van Cargo, 6.6 6SECTION Fuel Pump Relay
WARNING: This page is about a different car, the 2003 GMC Savana and 2003 Chevrolet Chevy Express. However, it is still accessible from the selected car via links, so may be relevant.

When ignition switch is turned to ON position, PCM turns electric fuel pump on by energizing fuel pump relay. PCM keeps relay energized if engine is running or cranking (PCM is receiving reference pulses from ignition module). If there are no reference pulses, PCM turns pump off within 2-20 seconds after key on.

As a back-up system to fuel pump relay, the oil pressure switch also activates fuel pump. The oil pressure switch is normally open until oil pressure reaches about 4 psi (27.6 kPa). If fuel pump relay fails, the oil pressure switch closes when oil pressure is obtained and operates the fuel pump. Cranking time will be longer if fuel pump does not receive current until oil pressure switch contacts close. Oil pressure switch may be combined into a single unit with an oil pressure gauge sending unit or sensor.

PCM monitors fuel pump circuit between fuel pump relay/oil pressure switch and fuel pump, enabling PCM to determine if fuel pump is being energized by fuel pump relay or oil pressure switch. A failure in this monitored circuit results in the setting of a related diagnostic trouble code in PCM memory.

For additional information on fuel pump activation, see SYSTEM & COMPONENT TESTING - 4.3L CHEVY EXPRESS & SAVANA article.

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Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
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