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Home >> Saab >> 1985 >> 900 S, 2D Hatchback, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Fuel Injection System - Turbo >> Testing >> System Circuit Test

System Circuit Test

  1. Remove fuel pump fuse (fuse number 30). Locate 2-pin connector for oxygen sensor preheating circuit (connector is attached to right-hand inner fender). Connect voltmeter leads across connector terminals. Set voltmeter to 12-volt scale. Crank engine and record voltage reading.
    CAUTION: Engine may start and run due to residual fuel in system.
  2. If voltage reading is incorrect, perform ELECTRONIC CONTROL UNIT test. If voltage reading is correct, go to next step.
  3. Remove fuel pump fuse (fuse number 30). Attach Fuel Pump Switch Harness (83 93 886), or jumper wire, between left connection of fuse 30 and right connection of fuse 27.
  4. Turn ignition on. If fuel system is operating properly, fuel flow through lines and injection manifold should be heard. If fuel system is not operating properly, perform FUEL PUMP DELIVERY PRESSURE  test.
    NOTE: When testing injectors, leave connections intact. Test by inserting voltmeter lead through back of connector.
  5. Connect voltmeter positive lead to Blue/Red wire of injector number 1. Connect negative lead to Green/Red wire of injector number 1. While cranking engine, voltage reading should be 3-5 volts. Repeat test for each injector. If no reading is indicated, go to ELECTRONIC CONTROL UNIT (ECU) test.
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