Note. To check the pressure in the fuel system, you will need a pressure gauge for the working pressure in the system and a set of adapters for connecting the pressure gauge to the elements of the system, including working injectors.
General Checks
1. Make sure there is fuel in the tank and that it matches the engine.
2. Check the operation of the fuel pump. To do this, ask an assistant to turn on the ignition, while you yourself stand near the fuel tank. You should hear the pump buzzing for about two seconds. During this time, the pump fills the pipelines and increases the pressure in the system.
Note. The operation of the pump can be clearly heard through the open filler neck of the fuel tank. If the pump does not work, go to step 10 and check the electrical purpose of the pump.
Note. On the Probe model, first check the inertial switch located in the trunk (pic. 3.2). The switch cuts off power to the fuel pump in the event of an accident. But it can also work by accident. for example, if something is dropped on it or from a slight collision when parking.
Checking the operation of the fuel pump and the pressure in the fuel system
3. If your model is equipped with a 4-cylinder engine and has the function "Cruise control". disconnect the actuator "cruise control", and slide it to the side without disconnecting the cable and wiring.
4. Connect a pressure gauge to the hose coming from the fuel filter (4 cylinder engine) or between fuel rails (V-engine) (pic. 3.4).
5. Turn on the ignition (do not start the engine) with the air conditioner off. The fuel pump will turn on for two seconds and the pressure gauge should register the pressure in the system, which should not change after that.
6. Start the engine, warm it up to normal operating temperature and let it idle. Compare the system pressure with the value given in Technical Data at the beginning of the chapter (fig 3.6). Now disconnect the vacuum hose from the fuel pressure regulator - the pressure should rise immediately. If the system pressure is Technical Data, means the system is working.
7. If the pressure did not increase when the vacuum hose was disconnected, connect a hand vacuum pump to the pressure regulator and create a vacuum in the regulator (pic. 3.7). If the fuel pressure has decreased, check the vacuum supply line to the regulator (including a solenoid valve as specified below in this paragraph). If all elements of the supply line are serviceable, and the pressure does not drop, replace the fuel pressure regulator.
8. If the pressure shown on the pressure gauge does not match the values specified in Technical Data, perform the following checks.
- A) If the pressure is higher than required, check if the vacuum is supplied to the regulator (pic. 3.8). The vacuum in the vacuum hose should change depending on the engine speed. If there is a vacuum, check for a blocked fuel return line. If the return line is OK. replace regulator.
- b) If the pressure is less than required, replace the fuel filter to be sure that it is not the problem. The procedure for replacing the filter is described in chapter 1. Another filter - mesh - is located at the fuel pump inlet in the fuel tank (see paragraph 5). If the pressure is still too low, start the engine (if possible) and slowly squeeze the fuel return hose. If the fuel pressure rises to 3 bar, replace the regulator (paragraph 14), Attention! Do not allow fuel pressure to exceed 4 bar.
- V) If the pressure is still low when the return hose is pinched, the cause may be a leaking injector (or nozzles) (see paragraph 15). The fuel pump itself may also be faulty.
9. After the checks, release the pressure in the fuel system again (see paragraph 2) and disconnect the pressure gauge.
Checking the power supply circuit of the fuel pump
Note. See Chapter 12 for detailed fuel pump and relay circuit diagrams.
10. If the pump does not work when the ignition is turned on (does not make sounds), check the pump fuse located in the fuse box in the engine compartment. If the fuse is blown, replace it and see if it works. If the pump is now running, look for a short circuit in the circuit from the relay to the pump.
Release models from 1993 to 1997
11. If the pump still does not work, remove the cover from the diagnostic connector in the engine compartment and short the fuel pump and ground contacts with a jumper (pic. 3.11). The pump should work.
Release models since 1998
12. If the pump still does not work, remove the pump relay from the relay box in the engine compartment. On 1998 models and 1999, bridge pins 30 and 37. On models from 2000, bridge pins 30 and GND (weight). Be careful. Short only these contacts.
All models
13. If the pump does not work, check if the power is supplied to the pump in the connector on the fuel tank (see wiring diagrams at the end of the manual). If there is voltage in the connector, then the circuit to the pump is working. Check for an electrical connection between the ground pin in the connector and the vehicle ground. If there is no connection, check the ground circuit for an open or poor connection.
14. If there is voltage and the grounding target is OK, replace the pump (paragraph 5).
Regulator Solenoid Check
15. This valve (not available on all models) interrupts the vacuum supply to the pressure regulator under certain engine operating conditions. Vacuum cutoff increases fuel pressure and prevents vapor lock.
16. If vacuum is not applied to the regulator, check this valve.
17. Locate the valve by following the vacuum hose from the fuel pressure regulator. Disconnect the vacuum hoses from the valve (see fig. 3.8).
18. Connect a piece of rubber hose to the valve inlet and blow into it. Air must pass through the valve
19. Disconnect from the valve an electric socket. Apply positive voltage from the battery to the positive terminal of the electromagnet, and connect the second terminal to ground. Now air should not pass through the valve.
20. If the valve does not work as described, then it is defective. Replace it.