Fuel Pressure Regulator – Its Importance in FIS

Most of the cars available in today's market are equipped with high performance electric fuel injection systems (FIS).

Most of the cars available in today's market are equipped with high performance electric fuel injection systems (FIS). The fuel pressure regulator (FPR) is a critical component of FIS. It helps FIS to function efficiently and it improves the overall performance of the car.

More about FPR
FPR is located inside the fuel tank in some models and on the fuel rail in other models. The prime function of the FPR is to maintain consistent pressure of fuel that is being pumped to fuel injectors on the engine. It ensures that the fuel rails contain enough amount of fuel and right amount of fuel is supplied to injectors irrespective of the changes in the flow of fuel.

FPR works at high load, high temperatures and is exposed to different types of chemicals present in the fuel. To sustain all these, FPRs are made of high performance and corrosive free materials. Thus, it is one of the strongest and most durable among all the components of FIS.

There are two types of FPRs available:
1. Fixed-rate
2. Adjustable
Adjustable FPR comes with the adjustable screw where you can adjust the pressure manually. In fixed-rate FPR, pressure is set automatically based on the driving conditions. It is always recommended to go with fixed-rate FPR unless you have sound knowledge of your vehicle’s fuel system and you can set pressure accurately.

FPR determines the performance of the vehicle
FPR is very important in FIS and it determines the performance of the car. It has two sides. One side is connected to the fuel rail where fuel enters and the other side has an inlet for air. FPR has a diaphragm and spring system that is attached to the bypass valve. It adjusts, opens and closes, on its own based on the demand for fuel. It makes sure that the optimal amount of fuel is pumped into the engine to maintain perfect ratio of fuel and air mixture.

Return fuel lines are attached to FPR through which excess and left out fuel is sent back to the tank.

When FPR is damaged or does not work properly, either more fuel is pumped to fuel injectors or less than required amount of fuel is sent to the injectors. Both the cases are problematic.

  • At high pressure: When FPR does not function properly and the pressure increases, excess fuel is sent to injectors resulting in wastage of fuel and it affects fuel efficiency badly.
  • At low pressure: When FPR cannot maintain pressure, it pumps less than the required amount of fuel to injectors. This leads to combustion (starting) problems and results in emission of black and toxic substances.


FPR not only plays a vital role in regulating the pressure of the fuel to the engine but is also environmental friendly as it reduces the emission of toxic substances.

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