Removal/refitting

REMOVAL/REFITTING

• Disconnect the battery (-) terminal.

1. Disconnect the electrical connection from the timing variator.
2. Disconnect the electrical connections from the electroinjectors and move the wiring to one side.
3. Disconnect the vacuum takeoff pipe from the pressure regulator.
4. Disconnect the fuel return and delivery pipes from the distributor manifold.

1. Slacken the two fastening screws and remove the fuel distributor manifold complete with injectors and pressure regulator and, if necessary, separate them on the bench.

ELECTROINJECTORS

The electroinjectors are installed on a new aluminium distributor manifold which on one side incorporates the pressure regulator. The injector nozzle is formed so that the jet of fuel atomizes into a 30° cone. The injectors are locked by the fuel distributor which presses them into their housings machined on the intake ducts.

The injectors are also anchored to the fuel distributor by "safety catches" and sealed by two O-Rings. The electroinjectors have the task of metering the amount of fuel needed by the engine. They are "ON-OFF" devices i.e. they only have two possible conditions, either open or closed. They will let the fuel pass when they are "open" and prevent it from being delivered when they are "closed".

They basically comprise a nozzle controlled by an electromagnet and by a return spring. In the rest position, the needle, which forms one piece with the core, is pushed by the spring onto the electroinjector nose to close the hole and ensure that unwanted fuel is unable to come out. As soon as the winding is energized, the core is attracted, it compresses the spring opening the nozzle hole, thereby allowing the fuel to flow out.

Considering the physical characteristics of the fuel (viscosity, density) and the pressure difference (pressure regulator) constant, the amount of fuel injected depends on the injector opening time only. The winding energizing time is normally called the "injection time".

1. Injector body
2. Needle
3. Magnetic core
4. Helical spring
5. Winding
6. Injector nose
7. Adjustable pressure plate
8. Filter
9. Electrical connection
10. Seal rings

CHECKING FOR CORRECT OPENING OF ELECTROINJECTORS

• Measure the quantity of CO at the exhaust.
• Disconnect the electroinjector connectors one by one; each time measure for a reduction of the CO quantity at the exhaust and check that this value remains constant at each check.
• If not, locate and replace the faulty electroinjector; in any case a visual index of the efficiency of the electroinjectors is given by the spark plug electrodes:

• a mixture which is too rich corresponds to a black colour.
• a mixture which is too lean corresponds to a light colour.