Nissan Repair: 1983 Datsun 280 zx Electrical ?, datsun 280 zx, crank angle sensor

Question
QUESTION: When the key is turned on the gas gage goes negative?
Also does not start, spark = ok, fuel pressure = ok, Injector continuity is ok, 12 volt at injector plugs, harness has 12 volts at the control unit.  If I jumper the cold start injector with 12 volts, I can get it to run at idle (just running on cold start injector)

ANSWER: Tom,

Either the ECM is defective or the distributor has failed.  You can take the distributor a part and look for oil on the optical shutter wheel.  If there is oil replace the distributor.  Now, on the gauges, you will need to check the output of the alternator.

---------- FOLLOW-UP ----------

QUESTION: The engine is not running or spinning for the alternator to have an output.  If the distributor was bad ,would the engine run when the cold start injector is manualy operated?

Answer
Tom,

Thanks for the clarification.  The distributor also sends the signal to fire the injectors.  Now, I would check the injector pulse width with a digital volt ohm meter or a noid light.  That way you will see if the car has injectors that are working.  My guess is, in this order, the injector fuses, the distributor or the ECM.  Now, if you have one of the 280ZX cars with a crank/cam angle sensor that could be bad too.  Somewhere back in the 280Z days the turbo version had a crank angle sensor seperate from he distributor.