Attention! See the warnings at the beginning Depressurizing the supply system.
Note. To check the fuel pressure, you will need a special pressure gauge with a wide scale range and an adapter to connect the pressure gauge to the injection system.
General Checks
1. Make sure there is enough fuel in the gas tank.
2. Make sure the fuel pump is actually working. Ask an assistant to turn on the ignition by turning the key to the ON position - a characteristic sound of a running pump should be heard in the gas tank for two seconds.
Note. The running pump is clearly audible through the open neck of the fuel tank. If the pump does not turn on, go directly to checking its electrical circuit (see paragraph 9).
Checking the pressure characteristic of the fuel pump
1a. Connect a dedicated pressure gauge to the test port on the fuel filter (see accompanying illustrations).
1b. The adapter is screwed into the hole for installing the service bolt (models for 1996 issue.), or instead of the hollow bolt of the union connection (models since 1997 issue.) (see Depressurizing the supply system).
2. Turn the ignition key to the ON position (without starting the engine), make sure A/C is off. The fuel pump will turn on for a couple of seconds - the pressure in the power system should rise (check the pressure gauge) and stabilize.
3. Start the engine and warm it up at idle to normal operating temperature. Compare pressure gauge reading with requirements Specifications. Now disconnect the vacuum hose from the fuel pressure regulator - the pressure should immediately rise, again to the specified in Specifications values.
4. If the pressure is too high with the vacuum hose connected, use the hand vacuum pump to (see accompanying illustration) create a vacuum in the regulator with a depth of 305 ÷ 355 mm Hg. Art. If the pressure drops, check that the vacuum source is working properly, otherwise replace the regulator.
5. If the pressure readings are out of range, perform the following checks:
- a) If the pressure is excessively high, check the supply to the vacuum regulator (see accompanying illustration). The depth of vacuum should fluctuate with changes in engine speed. If vacuum is present, check the condition and patency of the fuel return hose/pipe. If the return line is OK, replace the regulator.
- b) If the pressure is too low, change the fuel filter, eliminating the possibility of a violation of its patency. If replacing the filter does not correct the situation, install a shut-off valve between the regulator and the fuel return line (instead of a valve, you can install a piece of flexible hose, which can be easily pinched with tongs or a clamp). Start the engine and begin to slowly shut off the valve / pinch the hose. If the pressure rises above 3.2 kgf/cm2, replace the regulator (see Removal and installation of the throttle body).
Attention! Do not allow the pressure to rise above 4.2 kgf/cm2. Do not pinch the fuel return line itself to avoid the risk of damaging it.
- c) If the pressure remains excessively low even with the return line blocked, check the injector for leaks (s) injection (see Removal and installation of the fuel line and fuel injectors fuel injectors). Also check the fuel pump.
6. When finished checking, relieve pressure (see Depressurizing the supply system) and disconnect the pressure gauge.
Checking the electrical circuit of the fuel pump
Note. More detailed information on the scheme of an electric chain of the fuel pump contains in the Chapter Onboard electrical equipment.
1. If the fuel pump does not function when the ignition is turned on (no characteristic sounds are heard from the gas tank), check the condition of the main fuse (PGM-FI) injection system relay (see chapter Onboard electrical equipment). Replace the blown fuse and retest. If the pump starts to run after the fuse has been replaced, check the pump circuit wiring for signs of a short circuit between the PGM-FI relay and the pump.
2. If replacing the fuse does not restore the functioning of the pump, check the power supply to the latter. Remove the rear seat and check for battery voltage at the pump connector in the pump/fuel gauge assembly service cover. If power is good, replace the pump.
3a. If the pump is not powered, check the PGM-FI relay circuit. Ask an assistant to turn the key in the ignition lock several times from the OFF position to the ON position and vice versa (without starting the engine). At the same time, observe the appearance of battery voltage at the relay connector. Civic models - the relay is located on the right under the fairing.
3b. Integra models - the relay is located on the left under the fairing.
3s. With the ignition on, voltage must be applied to terminals 5 and 7 (see accompanying illustrations). If no power is applied, check the circuit for an open or short circuit (see wiring diagrams in Chapter Onboard electrical equipment this guide).
Note. On some models, oil pressure drops below a certain set point, the oil pressure switch acts as a shut-off valve, shutting off the fuel supply - check the switch and its circuit wiring (see wiring diagrams in Chapter Onboard electrical equipment).
Note. The anti-theft system provides for the immobilization of the fuel supply. A system failure will prevent the engine from starting. Also check the anti-theft alarm circuit.
4. With proper power supply, remove the relay for testing. Use a jumper wire to connect the positive battery terminal to terminal 2 of the relay socket. Ground terminal 1. Then check with an ohmmeter for continuity between terminals 4 and 5. If there is no continuity, replace the relay.
5. If there is continuity, connect the positive battery terminal to relay terminal 5, ground terminal 3. There should now be continuity between terminals 6 and 7, otherwise replace the relay.
6. If there is continuity, apply power to terminal 6, ground terminal 1 and check continuity between terminals 4 and 5. If there is no continuity, replace the relay.