Test Injectors

Test injectors

1.066There are four tests for injectors. Perform the tests in the following sequence:

  1. Opening pressure
  2. Leakage
  3. Chatter
  4. Spray pattern

 

Bleed tester

  • 1.067Remove carbon deposits from the injector tip with a small brass brush.
  • Mount the injector in the tester.
  • Turn the tester valve clockwise to close the gauge.
  • Operate the tester lever with rapid strokes to prime the tester and to bleed the injector.

 

Opening pressure1.068

  • Turn the tester valve knob counterclockwise to open the gauge.
  • Slowly depress the tester lever until the injector just begins to spray.
  • Read the opening pressure. Should be 120 to 142 bar.
  • Replace the injector if it is out of specifications.

 

Leakage

  • 1.069Install two pieces of vacuum hose on the injector return fittings to keep fuel from running down the side of the injector.
  • Dry the injector with compressed air or a lint free cloth.
  • Slowly depress the tester lever until the gauge reading is 20 bar below the measured opening pressure.
  • Hold the pressure for 10 seconds The injector should not drip.
    (A drop may form on the end of the injector – this is normal).

 

Chatter

1.070

  • Turn the tester valve knob clockwise to close the gauge.
  • Operate the tester lever with slow strokes. (1 to 2 strokes per second)
  • The injector should make a chattering or creaking sound if the injector is in good condition.
  • Disregard the spray pattern when checking chatter.  Spray pattern can only be checked at fast pumping speeds.

 

Spray pattern

  • 1.071Turn the tester valve knob clockwise to close the gauge.
  • Operate the tester lever with rapid strokes (4 to 6 strokes per second).
  • The spray pattern should be finely atomized and cone shaped.
  • Replace injectors which have a bad spray pattern.
  • The tester lever must be operated rapidly. At slow pumping speeds it is normal for the spray to stream or dribble out of the injector.

1.072

Safety

  • Do not put your hands near the injector when testing injectors. The high pressure diesel fuel spray can penetrate your skin and cause blood poisoning.
  • Always wear safety goggles when testing injectors.
  • The injector sprays a finely atomized combustible mist when testing. Avoid sparks and high heat sources when testing injectors.
  • Do not use gasoline as a “test fuel”.