Fuel Pressure Maintenance For The 1987 4Runner

The fuel pressure on a 1987 Toyota 4Runner 2.4 EFI should be between 17 psi to 20 psi. The fuel pressure can be tested by following these steps:

- Relieve residual fuel pressure by following safety precautions.

- Install the fuel pressure gauge at the appropriate location.

- Start the engine and observe the gauge reading.

- Compare the reading to the manufacturer's specifications.

Fuel pressure regulator test

To test the fuel pressure regulator on a 1987 4Runner, you can try the following:

First, pinch the vacuum line to the fuel pressure regulator and check if the engine remains running. You can also block off the fuel return line and observe if the vehicle stays running.

Another method is to pull the vacuum line on the fuel pressure regulator. If the regulator is functioning correctly, pulling the vacuum line should cause the engine RPM to surge upwards at idle. If there is no change in RPM, the regulator may be faulty.

You can also try sucking on a piece of hose connected to the regulator to test the diaphragm. If the diaphragm is intact, you should not be able to draw air through the hose.

Additionally, you can hook up a vacuum gauge to the line leading to the regulator to check for cranking vacuum. The reading should be around 2 inches of vacuum.

It is important to note that these tests may not be comprehensive, and further diagnostics may be required to conclusively determine any issues with the fuel pressure regulator or related components.

Fuel pump electrical circuit check

To check the fuel pump electrical circuit of your 1987 4Runner, you can perform the following steps:

• Check the fuses and the relay.
• Check the wiring diagram and locate the relay directly in control of the fuel supply, which is usually found in the passenger side kicker panel.
• Test the relay and then proceed to check the relay on the actual electric system.
• Hook up a voltmeter to the output lines of the relay to measure the voltage when the engine is cranked. Ensure that the voltage remains stable and does not drop after a few seconds.
• If the voltage drops, check the air cleaner switch, the EFI main relay, and the wires up to the fuel relay.
• Try the fuel pump test jumper between terminals FP and B+.
• Check the Circuit Opening Relay (COR) and its associated wiring. The COR is usually located in the passenger side kicker panel.
• Test the CO relay by following the instructions provided in the link: http://www.4crawler.com/4x4/CheapTri...shtml#FuelPump.
• If the CO relay is functioning correctly and clicking when energised, ensure that the relay contacts are not burned, pitted, or dirty.
• Check the wiring between the relay and the pump for any faults.
• Perform a fuel pressure test by connecting a vacuum gauge to the fuel pressure regulator. The cranking vacuum should be around 2 inches, and the fuel pressure specifications should be within the following ranges:
• With Fuel Pressure Regulator vacuum hose disconnected: 227-262 kPa (33-38 psi)
• With Fuel Pressure Regulator vacuum hose connected: 186-214 kPa (27-31 psi)

By following these steps, you can effectively check the fuel pump electrical circuit of your 1987 4Runner and identify any potential issues.

Fuel pressure test procedure

Firstly, it is important to note that the fuel pressure for a 1987 4Runner with a fuel pressure regulator vacuum hose disconnected should be 227-262 kPa (33-38 psi). With the fuel pressure regulator vacuum hose connected, the pressure should be 186-214 kPa (27-31 psi).

Now, onto the procedure. Park your car and engage the parking brake. Ensure you are in a well-ventilated area and take the necessary safety precautions, such as wearing safety goggles and gloves. Locate the fuel pressure test port, usually found on the fuel rail. Place a rag under the test port to catch any fuel that may be released during the test. Install the pressure tester onto the port and start the engine.

Run the engine at a specific RPM as per the manufacturer's instructions. For the 1987 4Runner, this information was not readily available. However, a typical port-injected vehicle should have a fuel pressure between 30 and 80 PSI. Check the vehicle's manual for the required fuel pressure and compare it to your recorded pressure reading.

If the fuel pump is not meeting the required pressure specifications, it may be failing to pump fuel to the engine, and it is time to consult a mechanic.

Additionally, there are a few things to keep in mind before performing the test. Firstly, ensure your fuel tank is not empty as this could be the reason your car is not starting. Secondly, verify that the fuel pump is working by listening for a two-second whirring or humming sound when the ignition is turned on. If there is no sound, check the fuel pump fuse, relay, and wiring.

Fuel volume test

To perform a fuel volume test, you will need to measure the volume of fuel that is pushed by the pump in a set amount of time. This can be done by disconnecting the fuel line and directing the flow into a vessel.

The simplest way to test fuel volume is to open the fuel supply line at the injector rail and measure the volume of fuel during a timed, power-on fuel pump test. However, this method involves pumping gasoline into an open container at a high rate, which poses obvious safety risks. Additionally, this test does not show how the pump will perform when under load.

Dedicated equipment is available to safely and conveniently test fuel volume and pressure. Most professional test gauges incorporate a volume test release valve that can be used to release fuel pressure or to provide an approximate indication of fuel volume.

When testing conventional two-line systems, the modulated pressure specification is tested by leaving the intake vacuum hose attached. Removing the vacuum hose with the engine running delivers an unmodulated fuel pressure reading. Both results should equal the specified values.

On single-line systems, the volume can only be measured from a disconnected fuel line. The fuel pump should produce at least three pints of fuel in 30 seconds.

It is important to note that a fuel pump is designed to provide 3 to 4 times the needed maximum volume of fuel to the engine. The excess fuel is then returned to the tank through the pressure regulator and return line. When the pump can only provide about half of the maximum volume, the pressure reading may still be fine at idle, but will drop under load, resulting in drivability issues.

Therefore, a volume test is necessary to diagnose fuel pump problems, as a pressure test by itself is insufficient.

Fuel pressure tester recommendations

If you're looking to test the fuel pressure on a 1987 4Runner, you'll need to get your hands on a fuel pressure test kit. This will allow you to check the fuel pump and fuel system on your vehicle.

There are a variety of fuel pressure testers available on the market, and here are some recommendations for you:

• The Innova Fuel Injection Pressure Tester from AutoZone is a good option. It offers free next-day delivery and in-store or curbside pick-up.
• AutoZone also offers the OEMTOOLS Fuel Pressure Test Kit, which comes with a limited-lifetime warranty.
• The Mityvac Fuel Pressure Tester Kit, also available at AutoZone, is another alternative.
• Amazon offers a wide range of fuel pressure testers, including the BETOOLL 0-140PSI Fuel Injector Injection Pump Pressure Tester Gauge Kit, which is a best-seller. It has a 4.4-star rating from almost 4,000 reviews.
• Another popular choice on Amazon is the Hromee Fuel Pump and Vacuum Tester Gauge, with a 4.4-star rating from 639 reviews.
• The Orion Motor Tech Fuel Pressure Gauge and Test Kit is also worth considering, as it comes with a range of hoses and adapters to fit most vehicles.
• If you're looking for a more comprehensive kit, the Universal Fuel Injection Gauge Pressure Tester Engine Diagnostic Oil Gauge Test Kit is suitable for cars, motorcycles, trucks, RVs, SUVs, and ATVs.
• For a more affordable option, the 0-140PSI Fuel Pressure Gauge Kit from Amazon offers a universal fit for most gasoline cars, trucks, and motorcycles.
• For those with a Cummins diesel engine or other diesel engines fitted with Compuchek Test Ports, the Moker TU-32-20 Compuchek Fuel Pressure Test Gauge is a good choice.
• The Handor Fuel Injection Pressure Tester Kit is another option, which includes a range of fuel line fittings to suit more engines.

Frequently asked questions