Fuel Pressure Regulator Buyer’s Guide
- The fuel pressure regulator is a device that controls the amount of pressure in the fuel injector rail.
- Blocking and Bypass styles are the two main types of fuel pressure regulators.
- Fuel pressure regulators are installed at the end of the fuel rail and are connected to the injectors of your car’s fuel injection system.
- The fuel pressure regulator’s job is to adjust the pressure in the fuel injector rail so that the fuel is sprayed in the desired amount all the time.
- The symptoms of a bad fuel pressure regulator include engine misfiring, black exhaust smoke, and fuel leak.
- Prices of OE fuel pressure regulator replacements on CarParts.com range from $4 to $1,800.
For your engine to function the way it should, fuel is uniformly sprayed by the fuel injection system from the fuel tank into the combustion chambers. But have you ever wondered how the fuel injection system maintains a fixed fuel supply in the engine’s chambers? Simple. The car is fitted with a fuel pressure regulator. To achieve efficient combustion, the injectors need to supply the engine with consistent amounts of fuel at the right pressure. This is where the fuel pressure regulator comes into play.
What is a fuel pressure regulator?
The fuel pressure regulator is a device that controls the amount of pressure in the fuel injector rail. It mainly consists of inlet and outlet ports, a control valve, a diaphragm, a spring, a threaded adjustment mechanism, and a boost/vacuum reference port. There are two main types of fuel pressure regulators known as the blocking style and the bypass style. Depending on the type, a fuel pressure regulator may feature two outlet ports or a fuel bypass valve and fuel return line port.
Types of fuel pressure regulators
If you are in the market for a replacement fuel pressure regulator, there are two types that you need to take note of, which are the bypass or return style and the blocking or non-return style. To help you determine which one to get, here’s a closer look at the two.
Blocking or Non-Return Style Regulators
Blocking style regulators feature a traditional regulator design that decreases fuel pressure and flow rather than sending excess fuel back to the tank. They do this by restricting the flow using a control valve. Fuel pressure in the fuel lines varies. The pressure is high along the lines connecting the fuel pump and the regulator and decreases from the regulator to the carburetor and fuel rail. An increase in fuel pressure inside the carburetor will cause the pressure in the regulator to rise, too. The increase will cause the fuel to push the diaphragm upward, causing the control valve to shut and reduce fuel flow.
When the engine begins to demand more fuel as you drive faster, the fuel pressure in the fuel lines drops. This will release the diaphragm, which would open the valve and increase fuel flow.
Bypass or Return Style Regulators
A bypass style regulator is distinguished by the presence of a bypass valve and a fuel return line. The fuel pump delivers fuel to the fuel lines and into the injector rail. The fuel then enters the inlet port and passes through the bypass valve, which regulates fuel flow and pressure. As pressure increases, the bypass valve opens and allows some of the fuel to flow back to the tank. The upward and downward movement of the bypass valve is limited by a metal spring. Remaining fuel then exits through the outlet port.
Where is the fuel pressure regulator located?
Fuel pressure regulators are installed at the end of the fuel rail and are connected to the injectors of your car’s fuel injection system. You can easily locate this small device by tracing the fuel lines connecting the rail to your intake manifold. In some cars, the fuel pressure regulator is attached to the firewall.
What does the fuel pressure regulator do?
As its name suggests, the fuel pressure regulator regulates the fuel pressure to match the air pressure inside the intake manifold. Ideally, your engine’s manifold pressure changes as you apply different pressure on the throttle. If the pressure inside the manifold becomes similar to the pressure of the injectors, fuel won’t flow. The fuel pressure regulator’s job is to adjust the pressure in the fuel injector rail so that the fuel is sprayed in the desired amount all the time. In short, the fuel pressure regulator is crucial in achieving the perfect ratio of the fuel and air mixture inside the combustion chambers.
Symptoms of a bad fuel pressure regulator
Like all failing components, the fuel pressure regulator also sends out signs when it is beginning to fail. Some symptoms are less problematic than others but it is important that you take action as soon as you notice them. Without further ado, here are the common symptoms of a malfunctioning fuel pressure regulator.
A malfunctioning fuel pressure regulator won’t be able to control the amount of fuel entering the intake manifold. The imbalance in the air-fuel mixture can cause the engine to misfire. Aside from misfiring, your engine might also suffer from decreased power, which then leads to slow acceleration.
Black exhaust smoke
A leak or mechanical failure in the fuel pressure regulator can cause the engine to run rich. When this happens, your vehicle would emit thick black smoke from the tailpipe. Black smoke from the exhaust could indicate different problems, and a failing fuel pressure regulator is just one. Be sure to let an experienced mechanic check your car as soon as you notice this issue.
The fuel pressure regulator can fail due to multiple causes, and problems surface over time. Among the problems, a fuel leak is one of the most common. This happens when the seals in the regulator fail, including the diaphragm.
You may also experience a decrease in fuel efficiency and loud noises coming from the fuel pump. These symptoms can be caused by different factors so before coming up with a conclusion, consult your trusted mechanic first. He or she will conduct a series of tests to trace the root of the problem, including visual inspection and the use of a fuel pressure gauge.
How much is a fuel pressure regulator?
Prices of OE fuel pressure regulator replacements on CarParts.com range from $4 to $1,800. There’s a wide range of standard OE replacement and performance regulators to choose from. All you have to know is which series or brand do you prefer. OE fuel pressure regulator replacements vary from their inlet and outlet sizes, color finish, and material. You may have yours as a solo piece, pair, or as part of a kit. To further narrow down your search, indicate your vehicle’s year, make, and model on the filter tab.
Steps in Replacing the Fuel Pressure Regulator
The amount of fuel pressure in an automobile shouldn't be too high. It shouldn't be too low either. Keeping it just right is the way to go. And that's exactly the job of the fuel pressure regulator.
If your fuel pressure regulator is about to give out on you, it'll certainly let you know. Below are some symptoms of a busted regulator:
- Black tail pipe smoke
- Blackened spark plugs
- Fuel leak in the tail pipe
- Fuel leak in the dipstick
- A noisy fuel pump
- Decreased fuel efficiency
- Engine problems (rough idle, difficulty in starting, among others.)
Difficulty: Easy to Moderate
- New fuel pressure regulator O-ring (necessary for some automobiles)
Step 1: Start by relieving the fuel pressure in your vehicle. This can be done by opening the fuel cap then taking out the fuel pump relay that's located in the engine's fuse box. After those, start the engine. Keep it running until it stalls, which should only take a few seconds.
Step 2: Disconnect the negative battery cable as well as all the lines and connectors that are attached to your old fuel pressure regulator.
Step 3: If the fuel pressure regulator is held to the engine, remove the bolts that are securing it in place. If the regulator isn't attached to the engine and is part of the fuel pump module instead, remove the upper and lower sections of the module in order to be able to detach the regulator.
Step 4: Once you've taken out your old fuel pressure regulator, put the new one in its place. Depending on your vehicle's make and model, you may need a brand-new fuel pressure regulator O-ring as well to keep the regulator in place. It's important that the new regulator is properly positioned. After securing it, you can re-bolt and reconnect the lines and connectors that you detached earlier.
Step 5: It's now time to re-pressurize your automobile. Reconnect the battery cable and restore the fuel pump relay to the way it was before. Don't forget to close the fuel cap as well. Afterwards, turn on your engine. Keep it on for several seconds then turn it off again. Repeat that a few times.