Signs of a broken fuel pressure regulator
Everything changed with the advent of the injector. Multi-point injection required, in comparison with the carburetor, not only colossal pressure, but also significantly different depending on the modes: 5-7 bar at speed and 3-3.5 at idle. For the fuel pump, which has become electric in injection cars, these numbers are not a problem. But excessive pressure can lead to premature failure of nozzles, seals and other components of the line.
WHY YOU NEED A PRESSURE REGULATOR
So, the fuel pressure regulator provides the required amount and optimal intensity of fuel supply to the injectors, maintaining normal pressure in the rail. It is a diaphragm regulator valve with two chambers: spring (air) and fuel. On the one hand, the fuel that enters the regulator through the inlet holes presses on the membrane, on the other hand, the pressure of the intake manifold, reinforced by a spring, acts on it.
It should be noted that the use of RTD in the fuel line is the most common, but not the only possible solution.
There are three main schemes for the implementation of fuel supply:
With return line. The regulator with this scheme is located at the inlet to the fuel rail. If the pressure created by the fuel pump is greater than the combined pressure of the spring and rail, the regulator opens the valve slightly and dumps excess fuel into the "return" through which it returns to the tank.
No return line. The pressure regulator in this case is located in the fuel tank, directly next to the pump.
Without mechanical regulator. In this scheme, the regulation of fuel pressure in the line is carried out by a fuel pump with an electronic control system, and a relief valve is provided to reduce the critical pressure.
In addition, there are hybrid schemes - for example, in the Common Rail system common among diesel engines, fuel also accumulates in the rail and there is a return line, but the discharge occurs through a valve controlled by the ECU based on pressure sensor readings. On German-made cars, fuel filters with a built-in regulator and a return line extending from them are quite often installed.
SIGNS OF A FAULTY PRESSURE REGULATOR
Fuel Pressure Regulator Malfunction. 4 Signs | Causes, Checking and Cleaning
The main symptoms of RTD failure are approximately identical for all types of structures, for gasoline and diesel engines.
Regulator malfunctions can be divided into two groups:
A critical drop in fuel rail pressure due to the RTD sending most of the fuel back to the tank.
The maximum increase in pressure in the rail - the fuel does not enter the return line.
In practice, due to the design features of the regulator, the first type of malfunction is much more common. In the process of natural wear, due to the influence of external factors (the presence of pollution or moisture in the fuel), the membrane loses its elasticity, the spring weakens, and the valve wedged.
Signs that the regulator is not holding the pressure required for the rail are:
difficult engine start, in all weather conditions;
unstable idling, floating speed;
slow or inadequate engine response to the gas pedal;
loss of dynamics during acceleration, jerks and dips;
reduction in engine power;
increased fuel consumption.
However, the increase in consumption occurs not only due to a lack of fuel in the ramp, when the driver tries to compensate for the unstable operation of the engine by increasing its supply, but, for obvious reasons, in case of an overabundance in the absence of a reset.
Other symptoms may indicate such a malfunction:
fuel leakage from the rail;
black exhaust smoke;
pops in the exhaust manifold.
Many of the above symptoms can also be caused by malfunctions in other components of the fuel system: gasoline pump, filters, electronic sensors, and others. In order to make sure that the fuel pressure regulator is malfunctioning, it is necessary to diagnose the car.
HOW TO DIAGNOSE A FAULTY RTD
Symptoms of a Faulty Fuel Pressure Regulator
One of the most reliable ways to determine a pressure regulator failure is to check (with the Check Engine light on) with a diagnostic scanner. On cars with OBD II, errors from the P0089 group (DTC P0089 00, -11, -12, -18, -19) should be determined, indicating a particular malfunction of the regulator.
On cars with old-style engines (usually carbureted ones) equipped with elastic rubber tubes of the fuel return line, to check the operation of the RTD, you can pinch the return line while the engine is running. The disappearance of symptoms, stabilization of work will clearly indicate a malfunction of the pressure regulator.
You can also check the RTD with a pressure gauge. A mechanical pressure gauge is connected to the engine power system by disconnecting the vacuum hose. The normal pressure in the rail of gasoline injection engines should be 2.5-3 kgf /
cm² (or, in a simple way, "atmosphere"). When the return is clamped (if possible), the pressure will rise by about 1 atmosphere. When the engine is turned off, only a slight decrease in pressure in the rail is allowed, if it drops to zero over time, it means that the RTD does not hold it, respectively, is faulty.
CONCLUSION
The fuel pressure regulator is an important element of the fuel system, without which the normal operation of the engine is impossible. The cost of the part and the work to replace it is quite small, therefore, at the first sign of a malfunction, it is recommended to contact professionals.