Injector Pressure Test

Fig. 2 Injection nozzle assembly exploded view:

Fig. 3 Injection nozzle spray pattern inspection:

Refer to ``DIESEL NOZZLE SPECIFICATIONS'' for specified nozzle opening pressures.
1. Remove injection nozzle assemblies from engine and nozzle seats and gaskets from nozzle assemblies, if equipped, keeping all components in order.
2. Install nozzles in suitable tester and apply sufficient pressure with tester to remove carbon from injection hole. Do not place hands in front of injection hole while nozzle is pressurized.
3. Slowly apply pressure to nozzle while observing tester gauge.
4. Record gauge reading just as pressure begins to drop and compare reading to specified nozzle opening pressure.
5. If opening pressure is not within specifications, replace shim on top of pressure spring, Fig. 2, with one that will provide specified opening pressure. Use only one shim in each injector. Varying shim thickness by 0.001 inch changes opening pressure by approximately 50 psi.
6. Maintain pressure on nozzle 142-284 psi below specified opening pressure while observing nozzle.
7. If any fuel drips from injection hole or leaks from around retaining nut within 10 seconds, repair or replace nozzle assembly.
8. Apply sufficient pressure to cause nozzle to ``shudder'' 15 to 60 times per minute and observe spray pattern, Fig. 3.
9. If pattern is incorrect, clean or replace nozzle.
10. Release pressure and observe nozzle. If any fuel drips from injection hole, clean or replace nozzle.


DIESEL NOZZLE SPECIFICATIONS

1. NEW NOZZLES-Injection nozzle opening pressures for all new nozzles are 2062-2205 psi except for the pickup model 4-2446cc engine, which is 2276-2389 psi.
2. USED NOZZLES-Injection nozzle opening pressures for all used nozzles 1920-2205 psi except for the pickup model 4-2446cc engine, which is 2062-2389 psi.