Fuel Pressure Norms For The 2009 Acadia

The 2009 GMC Acadia is a car with a lot of power under the hood. It has a high-pressure fuel pump that operates at over 2000 psi, and its fuel pressure regulator is attached to this pump, which is located inside the fuel tank. This system includes a fuel rail pressure sensor and delivers fuel through a feed pipe to the engine's combustion chamber. The fuel rail pressure should be around 508-798 psi, and the fuel pump relay may need to be commanded on several times to obtain the highest possible fuel pressure.

Fuel pressure issues and misfires

Symptoms

You may be experiencing fuel pressure issues if your GMC Acadia is exhibiting the following symptoms:

• Engine power reduced
• Intermittent missing, stumbling/hesitation, or loss of power
• "Check engine" light comes on
• Trouble codes P0300, P0302, P0304, P0306, P0087, P0089, and P0014
• Ticking sound under the hood, possibly from the driver's side under the throttle body
• Fluctuating fuel pressure readings (e.g., jumping between 38-44 psi)
• Strong fuel smell from the exhaust
• Service Stabilitrak message

Causes

• Fuel pump relay issues: The fuel pump relay may need to be commanded on a few times to obtain the highest possible fuel pressure.
• Restricted fuel feed pipe or plugged strainer: These can cause a decrease in fuel pressure and need to be inspected and repaired.
• Poor connections in harness connectors and ground circuits of the fuel pump: These should be inspected and repaired if necessary.
• Leaking fuel injectors: If the fuel pressure decreases more than 34 kPa (5 psi) within 1 minute, it could indicate leaking fuel injectors.
• Faulty fuel pressure regulator: A leaking diaphragm within the regulator can cause unmetered fuel to enter the intake manifold, resulting in a rich short-term and lean long-term condition.
• Faulty fuel injector: A faulty injector may not be delivering the correct amount of fuel, leading to a misfire.
• Vacuum leaks: Leaks in the vacuum system can affect fuel pressure and cause misfires.
• Faulty sensors: Incorrect or faulty sensors, such as the coolant temperature sensor, mass air flow sensor, or throttle position sensor, can affect fuel delivery and cause misfires.
• Ignition issues: Problems with the ignition system, such as incorrect spark plug gaps or weak spark, can lead to misfires.
• Fuel quality: Using low-quality fuel or allowing the fuel tank to run near empty can impact fuel pressure and cause misfires.

Diagnosis and Repair

To diagnose and repair fuel pressure issues and misfires in your GMC Acadia:

• Interview the customer: Ask about their driving habits, fuel tank levels, and any other issues they may have noticed.
• Obtain fault codes and freeze frame data: Check all modules for communication and address any "U" codes first. Then, retrieve fault codes and freeze frame data to understand the PCM's perspective during the issue.
• Observe data stream: Monitor oxygen sensor and fuel trim data, battery voltage, engine temperature, mass air flow (MAF), engine vacuum, and fuel pressure.
• Perform a fuel pressure test: Use a digital fuel pressure gauge and a scan tool to check the fuel pressure at idle and during operation. Compare the readings to the vehicle's specifications (e.g., 384-425 kPa or 56-62 psi for the GMC Acadia).
• Check the fuel injectors: Use an injector pulse tester to trigger the fuel injectors and compare the fuel pressure drop for each cylinder. A lower pressure drop indicates an issue with the injector.
• Inspect the fuel pump and sender assembly: Look for unusual wear on the camshaft lobes and replace the high-pressure fuel pump or camshaft if necessary.
• Replace necessary components: Based on your diagnosis, replace the faulty fuel pump, fuel injectors, fuel pressure regulator, sensors, or other relevant parts.
• Test drive the vehicle: After making repairs, test drive the vehicle under various conditions (e.g., acceleration, cruise, hard cornering) to ensure the issue has been resolved.

Case Studies

Case 1:

A 2009 GMC Acadia owner experienced intermittent engine power reduction, misfires (P0300, P0302, P0304, P0306), and low fuel pressure (P0087, P0089) issues. The problem was diagnosed as a faulty in-tank fuel pump, which was replaced, resolving the issue.

Case 2:

A 2009 Buick Enclave (which shares a platform with the GMC Acadia) exhibited stalling, sputtering, and fuel pressure issues (starting at 60 psi and dropping to 45 psi). The root cause was not identified, but the issue may have been related to a new fuel pump installed earlier that year.

Fuel rail pressure malfunction

A fuel rail pressure malfunction can be caused by a variety of issues with your 2009 GMC Acadia's fuel system. The fuel rail pressure sensor may need to be replaced, as a faulty sensor can cause incorrect pressure readings and trigger the malfunction indicator.

You can diagnose this issue by performing a fuel system check and circuit/system testing. To do this, you will need a scan tool that can read the "Actual Fuel Rail Pressure" parameter, as well as a fuel pressure gauge and a J37287 fuel line with a shut-off valve.

• Set up your vehicle with the fuel pressure gauge and the J37287 fuel line.
• Run the vehicle to purge all air from the fuel system, then shut it off and let it sit overnight.
• The next morning, turn the key to the "On" position without starting the engine.
• Using the fuel pressure gauge, verify that the "Key On" engine-off prime pulse fuel pressure is between 55-60 psi.
• This test will confirm the correct operation of the in-tank fuel pump assembly.
• Use your scan tool to also confirm the fuel rail pressure sensor reading, as this should be close to the low-side pressure reading from your fuel pressure gauge.
• Crank the engine to see if it fires. With the injector harness connectors unplugged, the injectors are electrically disabled, so no fuel should be delivered to the engine.
• If the engine fires, one or more injectors are leaking and introducing fuel into the cylinders. Reconnect the injector harness connectors and start the engine, letting it run for 10 minutes before shutting it down.
• Close the shut-off valve in the J37287 fuel line, which will separate the engine side of the fuel system from the rear section of the returnless fuel system.
• Monitor the low side of the fuel system for a drop in fuel pressure. With the valve closed, the system should hold at least 60 psi for a few hours.
• If you see a rapid decrease in fuel pressure, this indicates a leaking high-pressure fuel pump or leaking injectors.

Additionally, you can perform circuit/system testing to check for issues with the fuel pump relay, restricted fuel feed pipe, restricted or plugged strainer, or poor connections in the harness connectors and ground circuits of the fuel pump.

If you find that your fuel rail pressure sensor is functioning correctly and you don't have any other issues with your fuel system, then the problem may lie with your high-pressure fuel pump. In this case, you may need to replace the high-pressure fuel pump assembly or the camshaft, depending on the results of a visual inspection of the camshaft lobes.

It is important to note that diagnosing and repairing fuel system issues can be complex, and it may be necessary to consult a qualified mechanic or a GMC dealership for further assistance.

Fuel pump control module

The fuel pump control module (FPCM) is a vital component of the fuel system in a 2009 GMC Acadia, responsible for regulating fuel pressure and maintaining optimal engine performance. It is a serviceable GMLAN module, receiving desired fuel pressure messages from the engine control module (ECM) and adjusting the fuel pump's speed accordingly. The FPCM achieves this by sending a PWM signal to control the pump's duty cycle and vary its speed.

The FPCM is located under the rear of the vehicle, at the back of the fuel tank. It is designed to help power the fuel pump and ensure a smooth idle for the engine.

When experiencing issues with fuel pressure, such as codes P0087 and P0089, it is recommended to check the FPCM and related components. This may include testing fuel rail pressure, inspecting the fuel pump relay, and verifying the fuel pressure regulator's function.

In some cases, replacing the FPCM may be necessary. When doing so, it is important to use a GM-recommended replacement part, such as the ACDelco GM Original Equipment Fuel Pump Control Module, to ensure compatibility and optimal performance.

Additionally, the FPCM requires programming and/or special setup procedures as outlined in the GM Service Information. This information is crucial for ensuring the proper operation of the module in the vehicle.

Fuel pump replacement

Disclaimer: *This is a general guide for reference only. Always refer to your car's manual or seek a certified mechanic for professional advice and service.*

The fuel pump is responsible for delivering fuel from the tank to the fuel injectors. It ensures the right amount of fuel is delivered at a high enough pressure to keep the engine running smoothly. If your fuel pump is faulty, it can cause a loss of engine power, or even prevent the car from starting.

To replace the fuel pump in a 2009 GMC Acadia, follow these general steps:

• Disconnect the battery to reduce the risk of fire.
• Drain the fuel tank.
• Remove the fuel tank. You may need to use a floor jack to lower it down carefully.
• Disconnect the electrical connectors and fuel lines from the fuel tank.
• Remove the fuel pump module from the fuel tank.
• Install the new fuel pump module, ensuring all connections are secure.
• Reattach the fuel tank and refuel the vehicle.
• Reconnect the battery and start the engine to test the new fuel pump.

The cost of replacing a fuel pump can vary depending on your location and the specific model of your Acadia. On average, you can expect to pay between $771 and $1,005 for the parts and labor.

Note: *It is important to take all necessary precautions when working with the fuel system to prevent the risk of fire. Always refer to your car's manual or seek a certified mechanic for professional advice and service.*

Fuel pressure regulator location

The fuel pressure regulator in a 2009 GMC Acadia is attached to the fuel pump, which is located inside the fuel tank. It is situated at the end of the fuel line and connects to the car injectors.

The regulator ensures that enough fuel is injected into the engine to keep the car running. If the regulator is faulty, you may experience engine misfiring, a fuel leak, or black smoke coming from the engine as the excess fuel burns off.

To replace the fuel pressure regulator, you will need to remove the fuel tank and access the fuel pump. This process involves removing the fuel rail quick connects, electrical connections, and fuel filler connections, as well as supporting the fuel tank during the process.

It is important to note that working on fuel systems can be dangerous, and it is always recommended to seek professional assistance if you are unsure about any part of the process.

Frequently asked questions