Fuel Injection System - Diesel: Testing: Injectors

1. Remove injection nozzles from engine and install each nozzle in turn on an injector tester. Test injectors using an approved SAE calibration oil (208629 or J 9667 D) at room temperature. Bleed air out of tester by pumping handle several times.
2. Slowly lower tester handle and note pressure shown on gauge when injector nozzle opens. Injection starting pressure should be 1960-2030 psi (138-143 kg/cm² ). If injection starting pressure is not to specifications, adjust pressure by changing pressure pin spring shim.
3. Shims are available in sizes from 0.0197" (0.5 mm) to 0.06" (1.54 mm) in increments of 0.016" (0.04 mm). Changing shim thickness 1 size should result in a 68 psi (4.8 kg/cm² ) change in injection starting pressure.
4. Using injector tester, apply 1676-1746 psi (118-123 kg/cm² ) to injector. No fuel leakage should occur at this pressure range. If leakage does occur, injector must be disassembled and repaired or replaced.
5. Build up pressure in injector tester to just below injection starting pressure. Quickly lower handle on tester and observe fuel spray pattern. Fuel should be uniformly atomized and should form a narrow cone projecting straight out of the end of the nozzle. See Figure .

Fig 1: Ranger Diesel Quick Start System Diagram