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HOMESERVICE MANUALSOLDSMOBILE1985CUSTOM CRUISER 5.0 YREPAIR AND DIAGNOSISENGINE PERFORMANCETESTING & DIAGNOSISFUEL INJECTION SYSTEM - DIESELTESTINGINJECTORS
1985 Oldsmobile Custom Cruiser 5.0 Y

Fuel Injection System - Diesel: Testing: Injectors

1985 Oldsmobile Custom Cruiser 5.0 YSECTION Injectors
  1. Check the tightness of the fuel inlet fitting to injector nozzle body. Fitting should be tightened to 35 ft. lbs. (47 N.m).
  2. Remove injection nozzles. See Removal & Installation in this article. Clean carbon from tip of nozzle with a soft brass brush.
  3. Assemble injector to Diesel Injection Nozzle Tester (J-29075). Use a connecting line (high pressure) 12" long by 1/4" O.D. by 1/16" I.D. between injector and tester.
  4. Refer to test equipment manufacturer's instructions for exact tester operating instructions. Use SAE J967D calibrating oil at room temperature to test injectors.
    WARNING: DO NOT  use diesel fuel. It is unstable with respect to corrosion inhibition and may cause skin problems. When testing injectors, keep spray contained to avoid serious injury. Pressure of atomized test spray has sufficient penetrating power to puncture flesh.
  5. When testing opening pressure, handle of tester should be operated at a rate of 3 to 6 seconds for a full stroke. Minimum opening pressure for new nozzles on V8 models (Blue color band) is 1000 psi (70 kg/cm2 ).
  6. Opening pressure for V6 models (Red color band) is 800 psi (56 kg/cm2 ). Opening pressure is about 150 psi (10.5 kg/cm2 ) less for all used nozzles.
  7. When testing injector nozzle spray pattern, close pressure gauge and operate tester handle at a rate of 2 seconds per stroke. Fuel should be atomized at tip. There should not be a solid column of fuel or droplets formed.
  8. Note spray pattern and compare with examples shown. See Fig 1 . If incorrect, replace injector.
    Fig 1: Injector Nozzle Spray Patterns Keep spray contained to prevent injury to any body part.
    G646
  9. To test injector nozzle seat for leakage, decrease pressure to at least 290 psi (20.3 kg/cm2 ) BELOW actual opening pressure. Dry nozzle tip with compressed air.
  10. Increase pressure to 150 psi (10 kg/cm2 ) BELOW actual opening pressure. Maintain pressure for 5 seconds. Compare fuel leakage to examples shown. See Fig 2 .
  11. Replace defective injectors. Install carefully and tighten to specifications.
Fig 2: Checking Injector Nozzle Seat Tightness
G3352
RENDER: 1.0x

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Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
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  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.