Porsche Check Fuel Pressure

Is your Porsche engine misfiring, runs rough, black smoke from the exhaust, and the check engine light is on? Know how to diagnose the problem by checking the fuel pressure of your Porsche.

Symptoms

Let’s quickly look at common signs you may notice when you have low or no fuel pressure on a Porsche.

• Engine misfire
• Check Engine light on
• The car won’t start
• Engine runs rough
• The engine starts and then stalls.
• Turbo lag
• Black smoke from the exhaust
• Difficulty starting your Porsche

How to check Porsche fuel pressure

To do a fuel pressure test on a Porsche, you will need a fuel pressure gauge.

What you will need

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• Universal Fuel Pressure Kit
  • Some Porsche has Schrader valves, while others are M12x1.5, M14x1.5, and M16x1.5 ports. It is recommended to buy or rent a universal kit with various adapters.
• Clean rags
• Fire extinguisher in case of accidental fire

Procedure

1. Park the Porsche on a level surface and set the parking brakes. Allow the engine to cool down.
2. Next, you will need to access the engine. Pull the hood release under the dashboard to open the hood.
3. Remove the engine cover.
4. Locate the fuel rail. At the end of the fuel rail, you will find the test port. Most Porsches use what is known as a Schrader valve. Place a rag under the fuel port to catch fuel leaks. Remove the cap and connect your gauge.
5. Start the car to measure the fuel pressure with the engine running. Check the pressure with the engine running at 2000 RPM and 3000 RPM. Check fuel pressure at idle.

At idle, fuel pressure should be in the 45 to 55 PSI.

At 2000 or 3000 RPM, the pressure should be around 50-55 PSI.

If your Porsche struggles to start, you may want to check the pressure after turning off the engine. Keep the gauge connected for at least fifteen minutes after you shut off the engine. The pressure should stay constant. If you lose fuel pressure too quickly, you may have leaky fuel injectors or a fuel leak. Another issue could be a bad fuel regulator.

If your Porsche starts but stalls, the primary fuel pump could still be the problem. On Porsches with two fuel pumps, the secondary pump primes the system at startup, and the engine starts. A few seconds later, the engine dies. A bad primary pump will cause the engine to stall or run rough after startup. Like low fuel pressure, extremely high fuel pressure, such as over 100 PSI, can be a problem and cause the engine to run rough.

We hope you find the Porsche Check Fuel Pressure guide helpful. Check these troubleshooting and repair guides for more help on your Porsche.