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Cold Start Injectors

  1. Remove cold start injector valves from intake manifold. Place suitable container beneath each cold start valve, to catch discharged fuel. Disconnect negative "VE" connection at ignition coil.
  2. With engine temperature below 58°F (15°C), turn ignition on. Check that injectors do not leak. Crank engine 1-2 revolutions and make sure that injectors spray fuel. If injectors operate, end test procedure. If any injectors fails to operate properly, go to next step.
  3. Check for battery voltage at test point "V1" of cold start injectors. If battery voltage is present when cranking engine and injectors still do not spray, check electrical connections to each injector.
  4. If both positive and negative connections are okay, the injector is bad and should be replaced. If no voltage was present at test point "V1", check for voltage at test point "V2". See Figure.
  5. If voltage is present at test point "V2", check cables between cold start injector relay and cold start injectors. If no voltage is present, check for voltage at test point "V3".
  6. If no voltage is present at test point "V3", check supply voltage from fuel pump relay. If voltage is present at test point "V3", cold start relay is not functioning properly. Check for voltage at test point "V4".
  7. If no voltage is present at "V4", check supply voltage from starter relay. If voltage is present at "V4", disconnect terminal No. 85 of cold start relay and check for voltage at terminal No. 86.
  8. If no voltage is present at terminal No. 86, replace relay. If voltage is present, connect terminal No. 85 to ground and relay should energize. Now check voltage at terminal No. 87.
    Fig 1: Manifold Pressure Control Valve Test
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    Fig 2: V12 Engine Firing Order
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  9. If no voltage is present at terminal No. 87, replace relay. If voltage is present, check cable and connections to thermo-time switch. If cables are in good condition and making proper connections, go to next step.
  10. Replace cold start injectors and all cables and connections. Crank engine and check for voltage at terminal No. 87. Voltage at terminal No. 87 should be zero volts.
  11. If voltage is present at terminal No. 87, disconnect terminal No. 85. Crank engine and recheck for voltage at terminal No. 87. If terminal No. 87 has no voltage, thermo-time switch should be replaced. If voltage is present at terminal No. 87, replace relay.
    NOTE: If injectors spray fuel while voltage at terminal No. 87 is zero, injector should be replaced.
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