Volkswagen Air-Cooled 1970-1981 Repair Guide

Fuel Injectors

Print

There are two types of injectors. One type is secured in place by a ring that holds a single injector. The second type of injector is secured to the intake manifold in pairs by a common bracket.

CHECKING FUEL INJECTOR OPERATION



When the engine fails to run or runs erratically, always check the ignition system before assuming that the problem lies under that inscrutable tangle known as the fuel injection system. If the ignition system is functioning correctly, remove the injectors from the engine, leaving the fuel lines and wiring connected to them. Disconnect the high tension cable from the ignition coil to prevent the engine from starting and have an assistant engage the starter briefly.

See precautions in Tune-up for electronic ignition.


CAUTION
Raw fuel will be sprayed from the injectors if they are working, so have a container ready and do not smoke.

If a cone-shaped mist of fuel sprays in pulses from all of the injectors, they are working properly. If one or more injectors fail to spray, check the fuel injection signal.

To check for injector leakage, wipe the tips of the injectors dry with a clean, lint-free rag, then turn the ignition to ON (not START ). If the injector tips become wet with fuel but do not drip more than one or two drops per minute, it is a good possibility that the pressure regulator is set too high; if the injector loses more than one or two drops per minute, the injector is faulty and should be replaced.

CHECKING THE FUEL INJECTOR SIGNAL



You will need a mechanic's stethoscope to perform the second part of this test.

Unplug the electrical connector on the fuel injector and connect the leads of a test light to the two terminals of the connector. Disconnect the ignition coil high tension cable to prevent the engine from starting and have an assistant engage the starter.

See Precautions in Tune-up for electronic ignition.

The test light should blink, indicating the pulses of the injector.

Reconnect all fuel injector connections and run the engine. Place the end of the stethoscope on the fuel injector body. You should hear a clicking sound indicating that the injector is working properly. Failure to hear a clicking sound or hearing a sound different from the rest of the injectors probably indicates a faulty injector.

REMOVAL & INSTALLATION Single Injectors



See Figures 1 and 2

Click image to see an enlarged view

Fig. Fig. 1: Carburetor Specifications



Click image to see an enlarged view

Fig. Fig. 2: Exploded view of single injectors and intake manifold mounting

  1. Disconnect the negative battery cable.
  2.  
  3. Detach the fuel injector wiring.
  4.  
  5. Remove the nut which secures the injector bracket to the manifold.
  6.  
  7. If the injector is not going to be replaced, do not disconnect the fuel line. Disconnect the injector wiring.
  8.  
  9. Gently slide the injector bracket up the injector and pull the injector from the intake manifold. Be careful not to damage the inner and outer rubber sealing rings. These sealing rings are used to seal the injector to the manifold and must be replaced if they show any sign of deterioration.
  10.  
  11. Installation is the reverse of removal. Be careful not to damage the injector tip or contaminate the injector with dirt.
  12.  

Paired Injectors See Figure 3

Click image to see an enlarged view

Fig. Fig. 3: Exploded view of paired injectors and intake manifold mounting

  1. Disconnect the negative battery cable.
  2.  
  3. Disconnect the injector wiring.
  4.  
  5. Remove the two nuts which secure the injector bracket to the manifold. Slide the bracket up the injector. Do not disconnect the fuel lines if the injector is not going to be replaced.
  6.  
  7. Gently slide the pair of injectors out of their bores along with the rubber sealing rings, injector plate, and the inner and outer injector locating bushings. It may be necessary to remove the inner bushings from the intake manifold after the injectors are removed since they sometimes lodge within the manifold.
  8.  

There are two sleeves that fit over the injector bracket studs. Be careful not to lose them.

  1. Upon installation, place the injector bracket, the outer locating bushings, the injector plate, and the inner locating bushings on the pair of injectors in that order.
  2.  
  3. Gently slip the injector assembly into the manifold and install the bracket nuts. Be careful not to damage the injector tips or contaminate the injectors with dirt.
  4.  
  5. Reconnect the injector wiring.
  6.  
  7. Connect the battery.
  8.  

 
label.common.footer.alt.autozoneLogo