C 1500 Truck 2WD V6-262 4.3L VIN Z (1992)
Fuel Pump Relay: Description and Operation
Fuel Pump Relay
When the key is first turned ON, without the engine running, the control module will turn the fuel pump relay ON for two seconds. This builds up the
fuel pressure to normal operating pressure. If the engine is not started within two seconds, the control module will shut the fuel pump OFF and wait until
ignition reference pulses are present. As soon as the engine is cranked, the control module turns the relay ON, which powers the fuel pump. The control
module continues to power the fuel pump during engine operation. If the fuel pump relay fails, it is backed up by the oil pressure switch, which continues
to operate the fuel pump as long as oil pressure remains above 28.0 kPa (4 psi).
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A faulty fuel pump relay can result in long cranking times, particularly if the engine is cold.
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An inoperative fuel pump would cause a no start condition. A fuel pump which does not provide enough pressure can result in poor performance.
