Bmw E90 Fuel Pressure Regulator: Location Guide

The fuel pressure regulator is an important component in BMWs, and issues with it can cause significant problems for the car. The fuel pressure regulator controls the amount of fuel sent to the fuel injectors and maintains the correct air-fuel ratio for ignition. When the fuel pressure regulator starts to fail, the fuel mixture becomes too lean or too rich, causing issues with ignition. This can lead to black smoke emitted through the exhaust, discoloured spark plugs, fuel in the vacuum hose, and even engine backfiring or failure to start.

In the BMW E90, the fuel pressure regulator is located on the driver's side of the car, and replacement typically takes around 3 hours and is not technically difficult.

Symptoms of a faulty fuel pressure regulator

A faulty fuel pressure regulator can cause a range of issues with your BMW E90. Here are some of the symptoms to look out for:

• Long crank time: A faulty fuel pressure regulator can cause your BMW E90 to take longer than usual to start, especially when the engine is cold. This is often accompanied by strong cranks and the car eventually starting after several seconds.
• Fuel inefficiency: A bad fuel pressure regulator can lead to reduced fuel efficiency and increased fuel consumption. This is usually due to an incorrect air-fuel mixture or fuel leaks caused by faulty seals in the regulator.
• Black smoke from the exhaust: A leaking or internally damaged fuel pressure regulator can cause the emission of black smoke from the exhaust pipe. This is due to the engine running rich as a result of too much fuel being supplied.
• Fuel leaks: Faulty seals, rust, electrical issues, or a bad fuel pressure regulator can cause fuel leaks. Leaking fuel can lead to decreased engine performance and increased fuel consumption.
• Weak acceleration: A faulty fuel pressure regulator can result in weak or slow acceleration as the engine struggles to achieve the right balance between air and fuel. This can also be caused by a buildup of dirt on the injector tips.
• Problems when decelerating: A bad fuel pressure regulator can cause issues when decelerating, such as excessive gasoline buildup and engine backfire.
• Engine misfire: A faulty fuel pressure regulator can cause the engine to run rough and misfire, especially at idle. This is due to disturbances in the air-fuel ratio and engine tune.
• Engine fails to start: In some cases, a bad fuel pressure regulator can cause the engine to fail to start, even after multiple attempts. This is because the regulator is unable to maintain the correct fuel pressure when the engine is not running.
• Blackened spark plugs: A faulty fuel pressure regulator can cause black and feather-like deposits on the spark plugs, indicating a problem with the fuel mixture or wear.
• Whirring noise from the fuel pump: A noticeable whirring noise from the fuel pump, especially when starting the engine or accelerating, can be a symptom of a bad fuel pressure regulator.
• Gasoline in the vacuum hose: If you find gasoline in the vacuum hose, which is attached to the fuel pressure regulator, it could indicate a leak or damage in the regulator.

Location of the fuel pressure regulator

The fuel pressure regulator in a BMW E90 is located inside the fuel tank. To access it, you will need to remove the back seat of the car. Once you have located the fuel pump module, you will find the fuel pressure regulator connected to it by three main lines, which can be seen in Figure 10 of the replacement instructions.

The fuel pressure regulator is a crucial component in a BMW's fuel system, regulating the pressure and amount of fuel sent to the fuel injectors. When this part starts to fail, it can cause issues with the air-fuel mixture, leading to a rich or lean mixture and potential engine backfiring or failure to start.

It is important to note that working on the fuel system can be dangerous, and it is always recommended to seek professional assistance if you are uncomfortable or unfamiliar with the procedure.

How to replace the fuel pressure regulator

To replace the fuel pressure regulator in a BMW E90, follow these steps:

First, drain your fuel tank. Run the vehicle for about 20 seconds to equalize the amount of fuel in the siphon unit. Disconnect the negative battery cable. Remove the fuel cap, then slide an anti-static siphon hose down the fuel filler neck. Once the hose has reached the bottom, pump the fuel out of the fuel tank into a suitable storage container.

Next, remove the rear seat cushion by pulling up to detach the locking tabs. Peel the carpet away from the rear seat cushion area of the body. Remove the four 10mm nuts from the access panel and lift it away. Disconnect the fuel pump electrical connectors by squeezing the release tabs and pulling them off.

Now, remove the lines at the fuel pump by pressing the retaining tab and sliding the line off the fuel pump module. Be careful not to damage the hose or module. Unscrew the fuel pump module threaded collar. You can use a BMW special tool or a brass punch and rubber mallet for this. Tap the threaded collar on one of the ridges counter-clockwise to loosen, then unscrew the rest of the way by hand.

Remove the collar from the fuel tank and set it aside. Lift the fuel pump module up slightly and remove the top fuel line by pressing the retaining tab and sliding the line off. Work slowly and carefully to avoid damaging the line. With the upper fuel line removed, remove the top of the fuel pump module and set it aside.

Working inside the fuel tank, wrap a piece of mechanic's wire around the two black hoses at the bottom of the fuel pump module and pull them out, then press the retaining tab and remove the final fuel line from the module. With all the fuel lines removed, lift the fuel pump module out of the fuel tank and place it in a bucket to catch any dripping fuel.

When installing the new fuel pump, be sure to replace the fuel pump assembly sealing O-ring and install the new sealing O-ring on the fuel tank before placing the new fuel pump into the tank. Attach the lower fuel lines to the new fuel pump module, then slide the new fuel pump into the tank and connect the upper fuel line.

Align the tab with the fuel tank and press the new fuel pump into place. Hand-tighten the threaded collar, then use the BMW special tool or tap it tight with a brass punch and rubber mallet. Connect the external fuel lines and electrical connectors, then reassemble the interior.

Finally, fill the fuel tank with about 2 gallons of fuel before attempting to start the car. Once the new fuel pump is operating normally, fill the remainder of the fuel tank and check for leaks.

Common issues when replacing the fuel pressure regulator

The fuel pressure regulator in a BMW E90 is located inside the fuel tank, on the driver's side.

• Fuel leaks: Fuel leaks can occur if the regulator is not properly sealed or if the O-rings are damaged. It is important to carefully inspect the regulator and all seals before installation and to ensure that the regulator is securely tightened.
• Incompatible parts: Using aftermarket parts that are not compatible with the specific BMW model can lead to issues such as improper fitment, leaks, and performance problems. It is recommended to use OEM or high-quality aftermarket parts designed specifically for BMW vehicles.
• Fuel line issues: Disconnecting and reconnecting the fuel lines can be challenging, and it is important to do so carefully to avoid damage. Fuel lines may be difficult to reach or remove, and proper tools may be required to ensure a secure connection.
• Electrical issues: The fuel pressure regulator is controlled by the fuel pump control module, and electrical issues can affect the regulator's performance. It is important to check for proper voltage and ground connections to the fuel pump and control module.
• Fuel gauge issues: In some cases, replacing the fuel pressure regulator may affect the fuel gauge reading. This could be due to issues with the fuel level sending unit or other components in the fuel system.
• Long crank time: If the fuel pressure regulator is not functioning properly, it can cause long crank times or hard starting. This may be due to insufficient fuel pressure or volume, or issues with the fuel pump itself.
• Engine performance issues: A faulty fuel pressure regulator can cause poor engine performance, reduced fuel economy, and black smoke from the exhaust. It is important to diagnose and address these issues promptly to avoid further damage.

Fuel pressure regulator parts

The fuel pressure regulator is a crucial component of your BMW E90's fuel system, ensuring that the correct amount of fuel flows to the engine. It's located on the driver's side of the car, and replacing it can help solve issues with cold starts and long cranks.

When it comes to fuel pressure regulator parts, there are a variety of options available in the aftermarket, with prices ranging from $10 to $410. The regulator itself is just one piece of the puzzle—there are also hoses, O-rings, and other components that work together to maintain the correct fuel pressure.

Here's a more detailed breakdown of the parts you might need to replace or upgrade when working on your BMW E90's fuel pressure regulator:

The Regulator Unit

The regulator itself is the heart of the system. It controls the fuel pressure by allowing excess fuel to return to the tank, ensuring a steady supply to the engine. You can find aftermarket regulators from brands like GP Sorensen, Walker Products, and Holley, among others.

Hoses

The fuel pressure regulator is connected to the fuel pump by a series of hoses. These hoses can become brittle or cracked over time, leading to leaks. It's important to inspect them and replace them if necessary when working on the regulator.

O-Rings

O-rings are used to create a tight seal at various connection points in the fuel system. Over time, they can become worn or damaged, leading to leaks. It's a good idea to replace O-rings when servicing the fuel pressure regulator to prevent future issues.

Fuel Lines

The fuel lines connect the various components of the fuel system, including the fuel pressure regulator. They can become clogged or damaged, affecting fuel flow. It's important to inspect them and replace them if necessary.

Fuel Pump

While not directly part of the fuel pressure regulator, the fuel pump plays a crucial role in the fuel system. If it's not functioning properly, it can affect fuel pressure and flow, leading to issues that may be mistaken for a faulty regulator.

When replacing or upgrading your fuel pressure regulator, it's important to source parts from reliable manufacturers to ensure a proper fit and function. Always refer to your BMW E90's service manual or seek the advice of a qualified mechanic if you're unsure about any aspects of the repair or replacement process.

Frequently asked questions