Checking Fuel Pressure: 1987 Chevy Fi Guide

If you're looking to check the fuel pressure on your 1987 Chevy, you'll need to get your hands on a fuel pressure tester kit or any 0-100 psi gauge, as well as some adapters to connect it to the fuel rail's schrader valve. This process also requires a jumper wire or paper clip, and a wire with alligator clips on both ends. Checking fuel pressure is important for keeping your Chevy running properly and troubleshooting any issues. You'll need to test the pressure with the engine running and in gear, so be sure to set the parking brake and block all four tires for safety. With the right tools and precautions, you can confidently check the fuel pressure on your classic Chevy!

Using a fuel pressure tester kit

To check the fuel pressure on a 1987 Chevy, you will need a fuel pressure tester kit. These kits consist of a fuel gauge and the attached fuel hose. They can be purchased for $70 to $80.

Step 1: Prepare the Vehicle

Before beginning the test, ensure your fuel tank has at least two gallons of fuel. Even if your fuel gauge shows a full tank, it is better to confirm that the fuel gauge is operational. If it is not, you may have to manually inspect the tank to confirm it is full.

Step 2: Locate the Fuel Pump Test Point

Open the hood of your vehicle and locate the fuel pump test point. This is usually found beside the fuel injectors.

Step 3: Attach the Fuel Hose

Remove the cap from the fuel pump test point and attach the fuel hose from the tester kit. Ensure that the connection is secure and tight to prevent any leaks.

Step 4: Bleed the Fuel Pressure Gauge

Before taking a reading, bleed the fuel pressure gauge to release any air that may be inside.

Step 5: Activate the Ignition

With the fuel hose attached and bled, ask your helper to activate the ignition. Read the vehicle's fuel pressure level on the gauge and make a note of the levels.

Step 6: Remove the Fuel Pressure Gauge and Reseal

Once you have taken the reading, remove the fuel pressure gauge and replace the cap on the fuel pump test point before closing the hood of your vehicle.

Step 7: Compare with Specifications

Search for the specifications of your vehicle to understand the readings you should expect. This can be done by checking your vehicle owner's manual.

Understanding Fuel Pressure Readings

Zero Fuel Pressure

If the gauge shows zero, it could be due to a dead or non-operational pump. This may be caused by a loose connection at the end of the gauge or a faulty fuel pressure gauge. To confirm, test for power and ground to the fuel pump.

Low Fuel Pressure

Low fuel pressure readings may indicate a malfunctioning fuel pump. For example, a clogged fuel filter or a faulty pump. Check for loose gas caps, as this can prevent the tank from venting properly. If tightening the gas cap does not change the readings, you may need to change the fuel filter.

High Fuel Pressure

High fuel pressure readings could indicate bad components, such as a failing fuel pump driver or a malfunctioning fuel pressure regulator.

Safety Precautions

Fuel vapors are highly flammable, so ensure that these steps are performed in a well-ventilated area with a fire extinguisher nearby.

Locating the fuel pressure test port

Firstly, it is important to understand that the fuel pressure test port is usually located on the fuel rail, which is the tube that carries fuel to the injectors. On some vehicles, it may be covered with a black plastic dust cap, so keep an eye out for that. The exact location of the fuel rail and the test port can vary depending on the engine configuration. For example, on a 460 engine, the test port is typically on the passenger side of the engine, while on a 4.9L engine, it is on the driver side.

Before beginning the test, it is recommended to have a fuel pressure tester kit ready. Most large auto parts stores lend these kits out for free with a deposit. You will also need a jumper wire (or a paper clip) and a wire with alligator clips on both ends.

Now, let's locate the fuel pressure test port:

• Open the hood and look for the fuel rail. It is usually a chrome tube that runs along the top of the engine. Follow the fuel lines from the fuel tank or the fuel pump to the engine, as they will lead you to the fuel rail.
• Once you have located the fuel rail, carefully inspect it for the test port. It is typically a small metal fitting with a Schrader valve, similar to the valve on a car tire. There may also be a black plastic dust cap covering it.
• If you are having trouble locating the test port, you can refer to your vehicle's repair manual or seek assistance from a trusted mechanic.

Once you have located the fuel pressure test port, you can proceed with the fuel pressure test. Remember to exercise extreme caution when working with fuel systems, as gasoline is highly flammable. Ensure that you have the necessary safety equipment, such as safety goggles and gloves, before proceeding.

• Connect the jumper wire to the lower right terminal of the EEC test connector, which is located near the driver-side hood hinge.
• Use the wire with alligator clips to ground the jumper wire to a bolt head or another metal part of the engine.
• Attach the fuel pressure tester kit to the fuel pressure test port. Ensure that the adapters are not leaking.
• Turn the key to the 'run' position without starting the engine. With the jumper wire connected, the fuel pump should run constantly.
• Check the fuel pressure gauge with the key in the 'run' position and the engine off. This will give you the static fuel pressure reading.
• Start the engine and check the fuel pressure gauge again. The reading should be 5-10 psi lower than the previous reading, indicating that the fuel pressure regulator is functioning correctly.
• Finally, perform a wide-open throttle (WOT) test by having an assistant power-brake the truck (put the transmission in second gear, hold the brakes, and push the accelerator to the floor) for no more than 3 seconds. Alternatively, if you trust your parking brake and wheel chocks, you can open the throttle body wide open with your hand while monitoring the fuel pressure gauge. The fuel pressure should return to the same PSI as the 'key on, engine off, pump running' test, indicating a healthy fuel pump.

Remember to perform these tests safely and securely, and always refer to your vehicle's repair manual or seek professional assistance if you are unsure about any part of the process.

Checking the fuel pressure with the engine off

To check the fuel pressure in your 1987 Chevy with the engine off, you will need to purchase a fuel pressure tester. A good option is the Actron CP7838 Professional Fuel Pressure Tester, which can be found on Amazon. This tester is of good quality and is a reliable brand name.

Now, follow these steps:

Place a shop towel under the fuel filter to catch any fuel that may leak during the process.

Disconnect the fuel line from the fuel filter. It is important to disconnect the fuel line on the engine side of the fuel filter.

Connect the test adapter between the fuel line and the fuel filter. This will allow you to measure the fuel pressure.

Connect the fuel pressure gauge to the adapter. This will display the fuel pressure readings.

Ask your helper to cycle the key on and off but refrain from cranking the engine.

Check all your connections for any fuel leaks. It is important to ensure that there are no fuel leaks before proceeding to the next step.

If there are no fuel leaks, you can now crank the engine and check the fuel pressure gauge.

The fuel pressure gauge should register the specified fuel pressure for your vehicle.

Now, interpret the results:

• If the fuel pressure gauge registered 0 PSI, it indicates that the lack of fuel from the fuel pump is causing the engine not to start. This usually means that the fuel pump needs to be replaced, along with the fuel pump strainer and fuel filter.
• If the fuel pressure gauge registered the indicated fuel pressure specification, it means that the fuel pump is functioning correctly and sending fuel to the fuel injectors.
• If the fuel pressure gauge registered a fuel pressure significantly below the specification, it indicates that the fuel pump is failing and requires replacement. It is also recommended to replace the fuel pump strainer and the fuel filter in this case.

Checking the fuel pressure with the engine idling

To check the fuel pressure with the engine idling, first ensure the engine is running and idling. Then, check the fuel pressure gauge. The reading should be 5-10 psi lower than the 'engine-off' test reading, indicating that your fuel pressure regulator is working correctly.

For example, if the 'engine-off' test reading was 40 psi, the 'engine idling' test reading should be between 30 and 35 psi.

It is important to note that you will need a fuel pressure tester kit or a 0-100psi gauge with the correct adapters to connect to the fuel rail's Schrader valve. Additionally, you should set the parking brake and chock all four tires to ensure safety during the test.

If you are testing a truck with dual tanks, you will need to repeat this process for the other tank.

Checking the fuel pressure with the engine running

To check the fuel pressure with the engine running, you will need a fuel pressure tester kit or any 0-100psi gauge with the right adapters. You will also need a jumper wire or a paper clip and a wire with alligator clips on both ends.

First, locate the EEC test connector, which is usually found near the driver-side hood hinge. Connect the jumper wire to the lower right terminal of the EEC test connector, then use the wire with alligator clips to short the jumper wire to the ground.

Next, locate the fuel rail fuel pressure test port. This is usually covered with a black plastic dust cap and can be found on the passenger side or driver side of the engine, depending on your vehicle. It is attached to the chrome fuel rail and has the same threads as a tire's Schrader valve.

Connect the adapter from the fuel pressure tester kit to the fuel pressure test port. Then, attach the gauge to the adapter. Ensure that the key is in the 'run' position, but do not start the engine. Check the fuel pressure gauge adapters for any leaks.

After confirming that there are no leaks, start the engine and check the fuel pressure gauge again. It should now show a reading that is 5-10 psi lower than the previous reading with the engine off. This verifies that your fuel pressure regulator is functioning correctly.

For the final step, stand next to your vehicle and have an assistant perform a power-brake test by putting the transmission in second gear, holding the brakes, and pushing the accelerator to the floor for no more than 3 seconds. Alternatively, if you trust your parking brake and wheel chocks, you can open the throttle body wide open with your hand while observing the fuel pressure gauge. The fuel pressure should return to the same PSI as the previous reading with the engine off, indicating a healthy fuel pump that can keep up with the engine's fuel demand.

If the fuel pressure PSI drops below the previous reading, it suggests a weak pump that cannot keep up with the engine's demand.

Frequently asked questions