How to Test Fuel Pressure On Your Cars

by Contributing Writer

Your car is running poorly or not at all, I will show you how to test your fuel pressure to determine if that is the source of the problem.

Under The Hood:

 How to Check Fuel Pressure on a 5.9 12V Cummins

Pop the hood on the Dodge Ram and locate the test port on the left-hand front side of the engine compartment.

Unscrew the valve cap and pull it back out of the way. Screw the end of the fuel-pressure gauge onto the test port.

Start the Dodge Ram and allow it to run for around five minutes. Examine the fuel-pressure reading. If it still appears to be fluctuating, give it a few more minutes until the level peaks out. The pressure should read between 15 to 18 psi.

Turn the motor off and remove the pressure gauge from the test port. Use an old towel to wipe up any spilled fuel. Replace the test port cap.

Items you will need

  • Fuel-pressure gauge

 How to Test the Fuel Pressure on an Oldsmobile

Consult the Oldsmobile car manual specific to the model of your vehicle to find the location of the fuel pressure test port. These often come with the vehicle when purchased, but if it is missing, one can be ordered directly from GM, the manufacturer of Oldsmobile.

Attach the nozzle end of the fuel pressure gauge to the test port. If it does not fit properly you may need an adapter manufactured specifically for GM automobiles. It may be necessary to have one person hold the gauge while another runs the vehicle.

Turn the ignition key to the "Accessory" setting and write down the gauge readings. This will be the starting reference number. The Oldsmobile car manual will have specifications listed for fuel pressure in the section of the manual that discusses fuel pressure tests.

Start the vehicle and allow it to run for five minutes. Record the pressure ratings again. Compare both readings to the specifications listed in the owners manual. If there is a large difference, the vehicle will need to be inspected for fuel filter or fuel pump repairs.

Items you will need

  • Oldsmobile car manual

  • Fuel pressure gauge

  • GM adapters

  • Pen/pencil

  • Paper

 How to Check the Fuel Pressure in a Jeep Liberty

Detach the injector cover from the top of the engine using a ratchet and socket.

Connect a fuel pressure gauge to the fuel-rail test port near the fuel injectors. This port resembles the air valve on your Jeep tires. Wrap a shop towel around the test port as you connect the gauge to absorb any fuel spill.

Turn the ignition key to the "On" position.

Position the gauge bleed hose inside a suitable glass container and then open the gauge valve to remove any air in the line and leave the valve open.

Plug a scan tool to the vehicle computer data link connector located under the dashboard on the driver side.

Follow the instructions on your scan tool manual and activate the fuel pump. Then close the fuel-gauge bleed valve.

Make sure there are no fuel leaks around the gauge connections and read the fuel pressure on the gauge dial.

Compare the pressure reading to the one listed on the vehicle service manual for your particular Liberty model. If your reading is different from the one specified by your vehicle manufacturer, go on to the next step.

Turn the ignition key "Off" and repeat steps 3 through 8. However, this time block the fuel return hose using a pair of hose pinch pliers. This will isolate the fuel pressure regulator from your test.

Compare your pressure reading to the one specified by your vehicle manufacturer. If your reading is correct, your fuel pressure regulator might be defective. If you are still getting a different reading, go on to the next step.

Connect the fuel pressure gauge directly to the fuel-pump output hose. This will help you isolate other possible trouble spots, like fuel lines, fuel filter and regulator.

Compare your reading to the manufacturer number. If you get the correct reading this time, troubleshoot the fuel lines, fuel filter and regulator to isolate the problem. However, if your reading is still different, closely examine the fuel pump and troubleshoot it, if necessary.

Items you will need

  • Ratchet and socket

  • Fuel pressure gauge

  • Shop rag

  • Small glass container

  • Scan tool

  • Hose pinch pliers, if necessary

 How to Check the Fuel Pressure in a 2006 Nissan Titan

Testing the Fuel Pressure

Remove the two bolts on the front of the engine cover using a ratchet and socket, and lift the engine cover from the top of the engine. Place the cover in a safe location to prevent damage.

Find the intelligent power distribution module, which is the rectangular box located on the passenger’s side of the Titan’s firewall.

Open the IPDM and find the fuel pump fuse, which is the seventh fuse from the passenger’s side, in the top row of fuses. Pull this fuse with a slight wiggling motion to remove it. Set the fuse in a secure location for future re-installation.

Start the Titan’s engine and allow it to idle until the engine stalls. Crank the engine two additional times for five seconds each time to relieve any residual fuel pressure. Turn the ignition to the "Off" position.

Find where the fuel supply line connects to the Titan’s fuel rail inlet tube on the driver’s side of the engine and locate the cylinder-shaped plastic cover. Pull the cover upward to expose the connection point between the supply line and the fuel rail.

Guide a 5/16-inch fuel line disconnect tool to the inlet on the fuel rail, with the cylinder end facing the union point between the supply line and fuel rail. Wrap the connection point between the hoses with a clean, lint-free shop cloth to catch any residual gasoline. Pull upward on the disconnect tool and hold this upward force while pulling the supply line upward to disconnect it from the fuel rail inlet. Leave the disconnect tool inside the end of the fuel supply hose.

Connect the quick disconnect adapter No. J-44321, which is a part of fuel pressure kit No. J-44321, to the fuel pressure gauge. Guide the adapter through the hole in the disconnect tool, then press the tool upward and hold it. Press the adapter into the fuel supply hose as far as it will go, then release the disconnect tool to lock it into place. Tug lightly on the adapter to check that there is a good connection.

Connect the rubber hose included with the pressure kit to the inlet on the fuel rail. Tighten the hose clamp with a flat-head screwdriver.

Reinstall the fuel pump fuse into the IPDM and turn the ignition to the “Run” position for 10 seconds, then turn the ignition off for two seconds. Turn the ignition to the “Run” position again and check for any leaks from the gauge.

Start the engine and allow it to idle for roughly 15 minutes, checking the connections for fuel leakage every three minutes. At idling speed, the correct fuel pressure remains steady at roughly 51 psi. If the pressure is drastically low – more that 5 psi below the required pressure – there is a problem in the fuel system, such as a failed fuel pump, congested fuel lines or clogged fuel filter.

Removing Pressure Gauge

Relieve the fuel pressure following steps 3 and 4 in Section 1.

Wrap the connection point between the adapter and the fuel supply hose with a clean, lint-free cloth to catch any residual gasoline. Release the quick-release adapter from the fuel supply hose using the disconnect tool. Loosen the hose clamp on the hose connected to the fuel rail using a flat-head screwdriver. Remove the fuel pressure gauge and the quick disconnect tool.

Clean the end of both fuel tubes, the one on the fuel rail and the fuel supply tube, with a clean, lint-free cloth.

Apply a thin coat of new engine oil to the tip of the fuel rail tube to avoid damaging the O-ring inside the fuel supply tube. Guide the fuel supply tube over the fuel rail tube. Press the fuel supply tube downward until you hear the connector click into place.

Check the connection by verifying that you cannot see the white line painted on the fuel rail inlet tube and that the second flange on the tube is directly under the connector – there is no tube showing before the flange. Pull upward on the fuel supply tube with about 11 pounds of force to verify it made a good connection. If the fuel supply hose pops off, repeat the process from steps 3 through 5.

Reinstall the engine cover onto the top of the engine and tighten its retaining bolts to 49 inch-pounds, using an inch-pound torque wrench and socket.

Install the fuel pump fuse back into the IPDM and close the IPDM's lid. Turn the truck's ignition to the "Run" position for 10 seconds, then to the "Off" position for three seconds. Turn the ignition back to the "Run" position and check the connection point between the fuel rail inlet tube and the fuel supply hose for leaks.

Items you will need

  • Ratchet

  • Socket set

  • 5/16-inch fuel line disconnect tool

  • Fuel pressure kit No. J-44321 or equivalent

  • Flat-head screwdriver

  • Clean, lint-free cloth

  • New engine oil

  • Inch-pound torque wrench

 How to Test the Fuel Pressure in My 1992 Camry

Turn off the 1992 Camry's engine. Open the car's hood and support it with the prop rod.

Inspect the back half (close to the windshield) of the engine compartment to find the fuel rail. On the four-cylinder model, the fuel rail is very close to the windshield. On the V6 model, the fuel rail is between the center of the engine compartment and the windshield. The fuel rail is a large pipe that runs horizontal across the back half of the engine. It runs along the intake manifold.

Find the fuel pressure test port on the fuel rail. This is also called a Schrader valve. It looks very similar to a tire valve. It may have a cap on it. If it does, remove it.

Attach the fuel pressure gauge port to the valve. A small amount of fuel may come out of the connection. Be prepared to wipe it with a clean shop rag.

Hold the fuel gauge steady in your hand. Ask your assistant to insert the ignition key and turn it to the "On" position. Do not let your assistant crank the engine. As the fuel system pressurizes, you'll notice the gauge needle begins to move. After a few seconds, it will stay steady. The position it stays steady in is your fuel pressure reading. Ask your assistant to remove the key and then disconnect the fuel gauge and replace the cap, if necessary.

Items you will need

  • Fuel pressure gauge

  • Shop rag

  • Assistant

 How to Check the Fuel Pressure in a Toyota Truck

Locate the fuel supply line on the passenger side of the engine compartment. Remove the quick disconnect fitting on the supply line by hand.

Insert the t-fitting from the fuel-pressure testing kit into the fuel-supply line on one side, and the fuel-injection rail on the other. Connect the bottom of the t fitting to the fuel-pressure gauge.

Start the Toyota. Let the truck run and idle normally. Read the number on the gauge. If it reads between 40.8 and 41.7 psi, then your fuel pressure is correct. If it doesn't, then the fuel pressure regulator or fuel pump may be defective, and you need to do further testing to find out.

Items you will need

  • Fuel-pressure testing kit

 How to Check the Fuel Pressure on a 1995 Camry

Move the gear selector into the park position. Apply the emergency brake and turn off the engine.

Open the hood and find the Schrader valve. It is located on the end of the fuel rail tube on top of the intake manifold.

Remove the Schrader valve cap and attach the fuel pressure gauge. Position the gauge so it is visible from inside the car.

Turn the ignition to the “ON” position but do not start the vehicle. The fuel pump will energize for a 2- to 3-second period.

Note the reading on the fuel pressure gauge. Cycle the key between the “OFF” and “ON” position as necessary to obtain an accurate fuel pressure reading.

Items you will need

  • Fuel pressure gauge

 How to Test Fuel Pressure On Your Car

Locate the fuel pressure test port, you may have to refer to service information to locate this port or you may have to T into the fuel supply line.

Cycle the ignition key "on" and check your readings, write this number down. Start the car and run it, record your fuel pressure reading again. If your performance problem occurs when driving then you will need to take a road test to record the fuel pressure when driving. Tape the gauge to the windshield and have an assistant watch the gauge while you drive.

Compare your reading with specifications for your car, if it is low then I would start by replacing the fuel filter and retest. If there is no pressure then the pump may be at fault. Perform electrical tests on pump before replacing it.

Make sure everything is back together and no fuel leaks are present. Thanks.

Items you will need

  • Fuel Pressure Gauge

  • Adapters for your vehicle

 How to Check the Fuel Pressure for a Subaru Outback

Sit in the driver's seat of the vehicle, and turn the engine on. If the engine will not start, then have an assistant sit in the driver's seat for the remainder of this project.

Open the hood the of the vehicle, and locate the fuel rail, on the top side of the engine. The fuel rail is the metal rail that delivers fuel to the injectors. Locate and remove the fuel pressure testing cover from the fuel rail. The tester port cover looks like a valve stem cap from a tire and is sticking out from the fuel rail.

Insert the fuel pressure tester onto the fuel pressure testing port of the fuel rail by hand. If the vehicle is already running, take note of the pressure that the fuel rail is producing. This is the fuel pressure for your vehicle. If the vehicle is not running, have your assistant turn the key so that the engine turns over. Take note of the fuel pressure in the fuel rail when your assistant turns the key. Replace the fuel pressure testing port cap or cover when you are done taking your readings.

Items you will need

  • Fuel pressure tester

  • Assistant or second person

 How to Test Fuel Pressure on a 2.7L Dodge

Park you car outside so you have proper ventilation during the test.

Detach the injector cover from the top of the engine, if your particular Dodge model comes equipped with it. Use a ratchet and socket.

Locate the supply line and Schrader valve on your vehicle. This is the line the fuel injectors connect to. The Schrader valve is located on the end of the supply line. The valve looks like the air valve on the tires of your vehicle. You might need to unscrew a plastic cap from the valve.

Wrap a shop rag around the Schrader valve as you thread a fuel pressure gauge to the valve. Use the shop rag to catch any fuel squirting out of the valve as you connect the gauge.

Insert the end of the bleeding hose of the fuel pressure gauge into a 12-ounce container and open the gauge valve to bleed the air out of the gauge.

Connect a scan tool into the data link connector underneath the dashboard, on the driver's side.

Ask your assistant to turn the ignition switch "On," but do not start the engine. Have your assistant activate the fuel pump with the scan tool, following the instructions of the tool manufacturer.

Close the gauge valve as soon as you see gasoline flowing into the container through the bleeding hose and read the fuel pressure indicated on the gauge. On a 2000 Dodge Intrepid with a 2.7L V6, the gauge should indicate 58 PSI. Compare your reading to the one indicated in the service manual for your particular Dodge model.

Ask your assistant to turn off the scan tool, then turn off the ignition switch.

Remove the fuel pressure gauge from the fuel supply line. Replace the injector cover, if your particular Dodge model comes equipped with it, using the ratchet and socket. Close the hood.

Items you will need

  • Ratchet, if necessary

  • Socket, if necessary

  • Shop rag

  • Fuel pressure gauge

  • 12 ounces container

  • Scan tool

  • Assistant

 How to Test Fuel Pressure in a Ford Truck

Locate the fuel rail under the hood at the top of the engine. The fuel rail is what feeds fuel to the fuel injectors.

Remove the green or black screw cap from the nipple that protrudes outward from the fuel rail. This nipple is called the fuel pressure testing port.

Attach a fuel pressure tester to the port on the fuel rail.

Start the truck's engine.

Read the pressure on the fuel pressure tester. This is the amount of pressure that is reaching the fuel injectors. Replace the green or black fuel pressure port cap when finished reading the pressure data. The recommended fuel pressure for a standard Ford truck engine is 50 to 60 PSI. If the pressure falls more than 2 pounds below this recommendation, then you have a fuel sending problem or a possible leak.

Items you will need

  • Fuel pressure tester

 How to Check the Fuel Pressure on an Expedition

Raise the hood, put your safety glasses on and locate the fuel system test port, located in the fuel rail. Unscrew the cap on the port by hand and set it aside where you won’t lose it.

Connect the fuel pressure gauge to the port and maneuver the fuel pressure gauge under the hood near the cowl and up onto the windshield so you can lay it facing into the cab of the Expedition. Secure it in place by putting it between the windshield and the wiper blade.

Get in the driver seat of the Expedition and turn the ignition key to the run position, (one notch prior to actually cranking the engine over). The needle on the fuel pressure gauge should rise to approximately 32 to 45 PSI, depending on the year and engine of your Expedition. Watch the needle to make sure the pressure doesn’t drop off.

Shut the engine off and see if the pressure changes. It should remain constant, even after the key is turned off. This constant pressure keeps fuel in the injectors for quick start up. Start the engine again and tap the throttle; the needle should quickly rise roughly 5 PSI, then return to normal when the engine slows back down to idle.

Disconnect the fuel gauge from the fuel test port and reinstall the cap on the port to prevent dirt or other contaminants from entering the port and potentially causing a fuel leak.

Items you will need

  • Safety glasses

  • Fuel pressure gauge

 How to Check the Fuel Pressure in a 1999 Pontiac Grand Am

Turn your air-conditioner switch off, and then turn the ignition off. Open the hood and support it with the prop.

Inspect the rear part of the engine compartment near the intake manifold. Look for the fuel rail and the fuel-pressure test port. This port has a small Schrader cap on it. Twist the Schrader cap off to access the test port.

Attach the fuel-pressure gauge's fitting to the test port. Turn the ignition to the "On" position (don't crank the engine) to activate your fuel pump. Ideally, someone does this for you while you observe the fuel-pressure gauge.

Examine the fuel-pressure gauge. The reading should be between 41 and 47 psi. If the reading is too low, the likely culprit is a clogged-fuel filter. If the reading is too high, a number of problems could be the cause, including the fuel-pressure regulator.

Turn the ignition back to "Off," and disconnect the fuel-pressure gauge. Replace the Schrader cap.

Items you will need

  • Fuel-pressure gauge