BOSCH Cis Fuel Injection - MERCEDES-BENZ: Testing: Injectors

NOTE: Manufacturer recommends using Injector Tester (EFEP60 H) for this test. If tester is not available, use Pressure Gauge (100 589 13 21 00).

Remove air filter assembly. Unscrew fuel lines at injector nozzles. Ensure nozzles do not rotate when unscrewing fittings. Catch escaping fuel with cloth.
Remove hold-down brackets. Hold nozzles in place to avoid pulling out nozzles and insulators. Pull out injectors while keeping insulators in place in opening of intake. If insulators accidently come out, new "O" rings must be installed before placing them back into intake.
Connect injectors to tester. See Fig 1. Bleed pressure line with shut-off valve open and pressure line nut loose. Several strokes of hand lever should be sufficient for bleeding.
Tighten pressure line nut. With shut-off valve still open, depress hand lever slowly to build up pressure to maximum of 22 psi (1.5 kg/cm² ). If injector leaks (solid stream from nozzle), replace injector.
Close shut-off valve on tester and flush out valve with several rapid hand lever strokes. Open shut-off valve and slowly build up pressure with hand lever. Leak test again.
No fuel droplets should form within 15 seconds. Replace injectors that do not meet specifications. After installation, start engine and check for fuel leaks.

Fig 1: Injector Tester (EFEP60 H)
Courtesy of NOT AVAILABLE