How to Check the Fuel Pressure on Chevrolet Cars

by Contributing WriterUpdated June 12, 2017

The fuel pump in your Chevy Chevrolet car supplies fuel to the fuel injection system at a specific volume and pressure. When the fuel system isn't receiving the required fuel, indicated by symptoms including sluggish acceleration and poor fuel mileage, your diagnosis of the problem begins with a fuel pressure test. Testing the fuel pressure on this Chevrolet car requires a fuel pressure gauge designed for fuel injection testing. The average home mechanic can complete this test in just a few minutes with the right equipment.

Under The Hood:

 How to Check the Fuel Pressure on a 4.3 Blazer

Turn the Blazer off and open the hood.

Remove the protective cap from the fuel pressure test port. The port's location depends on the fuel injection type, whether the 1992 to 1995 central port injection (CFI) or the 1996 to 2005 central sequential fuel injection (CSFI)/multiport fuel injection (MFI). The CFI port is behind the intake plenum next to the distributor, and the CSFI/MFI port is about the left valve cover behind the positive crankcase ventilation valve tube.

Connect the fuel pressure gauge to the fuel pressure test port. The system is pressurized, so cover the test port and pressure gauge line fitting with a shop rag. Set the gauge's bleed hose in a container approved for gasoline.

Turn the ignition to on without selecting start and have an assistant look at the fuel pressure gauge. It should read 60 to 66 psi.

Bleed the air from the pressure gauge. Turn the ignition off and wait at least 10 seconds.

Turn the ignition back on without selecting start to cycle the fuel pump, pressurizing the fuel system. Wait 10 minutes, then read the gauge. It should not read less than 5 psi below the initial pressure reading or below 55 psi.

Bleed the system pressure with the gauge until the gauge reads 10 psi. Wait 10 minutes then read the gauge again. It should not read less than 8 psi.

Start the engine and allow it to warm to operating temperature. Depress the throttle pedal momentarily while an assistant reads the pressure gauge. It should not rise above 66 psi.

Turn the engine off. Disconnect the fuel pressure gauge from the fuel pressure test port then remove the shop rag. Replace the protective cap.

Dispose of any gasoline in the container in accordance with local policy.

Items you will need

  • GM J347301A or similar fuel pressure gauge

  • Approved gasoline container

  • Shop rags

 How to Check Fuel Pressure on a '99 Tahoe

Park your Tahoe in a well ventilated area and open the hood.

Take the injector cover off the top of the engine using a ratchet and socket.

Find the Schrader valve on the fuel rail. This is the fuel tube that holds the fuel injectors. You might need to unscrew a plastic cap off the valve. You will recognize the valve because it is similar to the air valve on your Tahoe tires.

Wrap a shop rag around the valve to prevent fuel spilling over the engine or yourself when connecting the fuel pressure gauge.

Connect a fuel pressure gauge to the Schrader valve.

Insert the gauge bleed hose into a 16-oz. or larger container to catch the fuel during this test.

Ask an assistant to turn on the ignition without starting the engine.

Open the bleed hose valve on the gauge to bleed the air from the fuel system.

Connect a scan tool into the Assembly Line Diagnostic Link electrical connector located under the dashboard on the driver’s side.

Ask your assistant to activate the fuel pump using the scan tool following the tool's instruction manual.

Close the gauge’s bleed hose valve as soon as fuel begins to bleed into the container without air bubbles.

Read the gauge. Fuel pressure should be between 60 and 66 psi.

Turn off the ignition. Disconnect the scan tool and fuel pressure gauge.

Close the hood.

Items you will need

  • Ratchet

  • Socket

  • Shop rag

  • Fuel pressure gauge

  • 16-oz. container or larger

  • Assistant's help

  • Scan tool

 How to Check the Fuel Pressure on a 1990 Chevy Truck

Remove the fuel pump fuse. Use a fuse puller because the GM truck fuses are pushed deeply into the fuse panel and are hard to grasp with fingertips. Start the truck and let it run until the engine dies. This will purge all the high-pressure fuel from the fuel line.

Raise the hood of the truck and remove the air filter assembly. At the rear of the throttle body are two fuel lines--one to supply fuel and the other to return the excess fuel to the fuel tank. The larger of the two lines (located on the right-rear of the throttle body) is the fuel supply. Remove this line from the throttle body with a wrench and screw the fuel pressure adapter (comes with the fuel pressure tester) into the throttle body, then attach the fuel supply line to the adapter.

Install the fuel pressure gauge to the adapter. Reinstall the fuse and start the truck. Depending on the engine size, the fuel pressure should read between 35 and 40 psi.

Remove the fuel pump fuse and let the engine run until it dies. Remove the gauge and adapter, reinstall the fuel supply line and air cleaner assembly. Lower the hood, install the fuse and start the truck. Inspect the truck for fuel leaks.

Items you will need

  • Fuse puller

  • Fuel pressure tester kit

  • Wrench set

 How to Check the Fuel Pressure of a Chevy S-10 4.3L TBI

Open the gas door on the S-10, and open the gas cap. Pop the hood and take off the air cleaner on the engine by removing the wing nut on the air cleaner, then removing it from the engine.

Locate the flexible fuel line leading into the TBI system on the top of the engine. Disconnect the flexible fuel line by pinching the quick disconnect connection on the fuel line using your hands. Connect fuel pressure gauge J-29658 in line between the flexible fuel line and the TBI system with your hands.

Start the engine with the ignition key. Let the truck warm to operating temperature. Look at the fuel pressure gauge and read the number on the gauge. This number should be between 9 and 13 PSI for the fuel system to be functioning correctly.

Items you will need

  • Fuel pressure gauge J-29658

 How to Check the Fuel Pressure on an S10 Truck

Attach the fuel pressure gauge to the fuel pressure test port located on the inlet fuel line. This is the smaller of the two fuel lines, and the test port is located on the driver's side of the engine compartment, near the injectors, in the S-10. Remove the black plastic dust cap and screw the fitting on the end of the gauge hose onto the test port.

Cycle the ignition from the off position to the run position and then to the off position three times. Leave the key in the run position on the last cycle. Read the pressure indicated on the test gauge. On the S-10, it should be 41 to 47 psi with the engine off and the key on.

Start the engine. The pressure should drop slightly to around 35 psi with the engine running and rise slightly when the accelerator is pressed quickly. If the fuel pressure is low, in either test, suspect a faulty fuel pump. If the pressure fails to rise when the accelerator is opened, suspect a faulty fuel pressure regulator.

Items you will need

  • Fuel pressure gauge

  • Service manual

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