Gadgets that are usually put between injector on one and the tank on the other side are called performance fuel regulators. Their function is vital for proper work of your engine. They control the flow of fuel and make sure that the gas is always under enough pressure. Fuel pressure is measured in PSI – pond per square inch.
There are different models, sizes, shapes but their only function is to keep the fuel pressure above intake manifold. As long as there is enough pressure, there will be optimum level of fuel injected into the tank. Sounds simple. Also, if there is more fuel being injected than it’s need, then the excess fuel is restricted and returned to tank. That really is a money saver and ensure optimum engine performances.
Fuel pressure regulator is often cylindrically shaped. It usually made of metal and placed at the end of fuel rail. Fuel rail is basically the pipe that holds for distribution to the injectors.
Typically, fuel pressure regulators are necessary only if you had done aftermarket modifications to your car and engine.
Fuel regulators are very reliable devices. And besides that, some of them can be self-adjusting. That means that they automatically adjust the fuel pressure to match optimum fuel consumption.