Fuel Injectors, Servicing

FUEL INJECTORS, SERVICING

The diesel fuel injectors for the AAZ engine are designed with two springs to control injector opening, and the injection of fuel takes place in two stages.

If these two-stage injectors malfunction they must be replaced, as opening pressure is not adjustable and they cannot be repaired.

Check 1st-stage opening pressure and check for leakage as described below.





Fuel injectors, checking

WARNING! When testing injectors make sure that the fuel jet does not strike your hand. The high opening pressure will cause the fuel to penetrate the skin and may cause severe injuries.

Injector spray, checking (visual)
If the needle is broken off or bent, replace injector or nozzle body together with needle as an assembly.

Opening pressure, checking
Pressure gauge open:
- Move pump lever down slowly. When spray emerges, take reading of opening pressure.

Specifications (overpressure):
- New injectors 150-158 bar
- Wear limit: 140 bar

Leakage test
Pressure gauge open:
- Slowly press pump lever down and maintain a pressure of 110 bar for approx. 10 seconds. No fuel should leak from the nozzle tip.