Fuel Pressure Regulator
February 9th, 2022 by Walton Motorsport
The Fuel Pressure Regulator
With the much-anticipated launch of the new Turbosmart FPR range, maybe we should talk about the Fuel Pressure Regulator?
In a vehicle’s fuel system. Firstly, you have a fuel pump. Secondly, you have injectors. The injectors require a specific amount of fuel pressure behind them. However, the fuel pump typically pumps at a set rate. This is where the regulator comes in. This will keep a set amount of pressure behind the injectors (commonly 3bar in the aftermarket world) and bleed the rest of the fuel off back to the tank. In essence, The fuel pressure regulator bleeds off unwanted fuel through its outlet port. They are most commonly mounted at the end of the fuel rail.
On a turbocharged car, The injectors need more fuel pressure to overcome the cylinder pressure. As a result, this allows the injectors to perform in the same way regardless of the cylinder pressure. The way this is achieved is by referencing the FPR to the boost system. As the boost increases the regulator’s baseline moves and keeps the same amount of pressure regardless. For example, Idling at 20inHg, the fuel injector nozzle is exposed to 20 inHg vacuum causing fuel to be sucked into the intake manifold. This combined with the 40 PSI base pressure would equate to a theoretical spray pressure of 50 PSI. This is above the desired fuel pressure of 40 PSI. Since the top of the valve in the FPR is also exposed to 20 inHg. The valve is pulled up which opens the outlet port up to increase the fuel being bled from the fuel rail. Further, reducing the pressure by 10 PSI. This then gives you your desired fuel pressure of 40 PSI.
The better fuel pressure regulators on the market (such as the Turbosmart Range) maintain very consistent pressure. cheaper options do not. which can be bad news for your engine.
Fuel Pressure Regulator FAQs