Fuel Injector: Testing and Inspection

CHECKING FUEL INJECTORS

General

Instructions for checking the injectors apply to vehicles equipped with either mechanical or CIS fuel injection.

The injector tester is used for checking opening pressure, spray pattern, and leakage of injectors.

Fill container of the tester with testing oil and bleed tester prior to testing the injectors. Use only testing oil 01 61 v 11.

Under no circumstances should gasoline be used.

When testing injectors for the mechanical injection system, use pressure gauge EF 1687 231 000 0 - 25 bar. When testing CIS injectors use pressure gauge with calibrations 0 - 6 bar.

Bleeding the Tester




1. Open bleeder screw.

2. Open pressure gauge valve.

3. Actuate hand lever until testing oil comes out of the bleeder without air bubbles.

4. Tighten bleeder screw.

5. Connect injector to pressure line but do not tighten connection. Actuate hand lever until air bubbles cease to come out at the coupling nut.




6. Tighten injector pressure line.

Checking Injectors

Note:
The injectors of one engine can be replaced separately.
Defective injectors cannot be repaired, but must be replaced.

Checking

Operate hand lever slowly (about 2 sec/stroke) with the pressure gauge shut-off valve open. In this manner a valve leaking because of a large particle of dirt can be recognized (tight spray on valve, pressure built up to max. 1.5 bar)

Checking Opening Pressure

1. Flush injector with the pressure gauge shut-off valve closed by moving lever back and forth several times quickly.

2. Open pressure gauge shut-off valve and read opening pressure on pressure gauge while moving lever slowly (about 2 sec/stroke)



The opening pressure is:
15 to 18 bar (mechanical injection system)
2.5 to 3.6 bar (continuous fuel injection)

Replace injector, if opening pressure is outside of these tolerances.

Caution! When pressure gauge shut-off valve is open increase pressure slowly to avoid damaging the pressure gauge.

Checking for Leaks

Mechanical Fuel Injection

1. Open shut-off valve on pressure gauge until the pressure on the pressure gauge has dropped below 15 bar.

2. Operate hand lever slowly until a pressure of 2.0 bar less than the measured opening pressure is reached.

No drops should form on the valve within 15 seconds when the pressure is 2 bar less than the opening pressure.

Continuous Fuel Injection

1. Close pressure gauge shut-off valve and flush injector by operating lever many times,

2. Open shut-off valve and increase pressure slowly to 0.5 bar less than the previously measured opening pressure (but not below 2.3 bar), and hold.
No drops should form on injector within 15) seconds.

Humming Test / Checking Spray Pattern




1. Close pressure gauge shut-off valve and flush injector by operating lever many times (0.5 sec./stroke).

2. Then reduce lever movement to about 1 sec./stroke. This must cause injector to hum. No drops should form on injector. A tight spray pattern is not allowable. An atomized, one-sided spray pattern of about 35° is permissible.