Fuel Pressure Regulator - Controls The Exact Amount
Fuel Pressure Regulator – Controls The Exact Amount

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Fuel Pressure Regulator – FAQ – Do You Have The Correct Pressure

Fuel Pressure Regulators – Function, Failure Symptoms And Testing


So, Fuel Pressure Regulators – Control The Exact Amount Of Pressure

All fuel-injected vehicles have regulators to; maintain a regulated amount of fuel flow, through the fuel system. Fuel injectors require, a set amount of pressure at the nozzle; at all times while in operation. Consequently, fuel injectors do not operate by; increasing or decreasing the opening for fuel flow. They simply open the same; but for a longer or shorter duration; as needed.

Pressure can run between 25 to 60 pounds; depending on the vehicle and manufacturer. All vehicles will have a fuel pressure regulator; on the fuel rail, containing the fuel injectors. The fuel regulator uses a diaphragm and spring combination; with a vacuum source on the top side of the diaphragm. Consequently, to counteract the spring pressure when high demand dictates; that higher pressure is necessary.

The computer uses, sensors to determine everything from:

  • Air density
  • Air temperature
  • Temperature of the engine
  • Load on the engine
  • Position of the throttle

The computer takes this information and decides on a strategy; to get the best performance out of the engine. So, one of these strategies is; to determine how long to keep the fuel injectors on. Consequently, to maintain this fuel ratio; the fuel pressure must be maintained, within one pound. When the engine is suddenly under heavy acceleration; the vacuum drops off. Only, momentarily and then recovers; within a very short period of time.

This sudden drop in vacuum during acceleration; also affects the pressure. As a result, the injectors are suddenly opened longer. The fuel pump takes a second to catch up with the pressure. So, the regulator reacts to the drop in vacuum; by closing the fuel return line momentarily. Finally, this gives a momentary boost in pressure.

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