Nissan Repair: charging system 87 nissan 300zx, nissan 300zx, great drain

Question
2 new alternators and batteries later The charging system is putting 12.25 volts into the battery, diconnecting the charge wire from the battery while running the alt. puts 14.35 volts, this is on a multimeter and dash gauge. the engine idles up and runs smoother when the battery is unhooked, I have run many test and have not found any shorts,If I charge the battery fully the alt. put out 14.35 for a short period maybe 30 minutes and then starts all over with the problem . it does not drain the battery while parked a week at a time . its like a discharge while running only, any info would be greatly appreciated .alot of hours of troubleshooting already involved. another question is : are the injector wires supposed to have 12 volts on them with the ign off ?

Answer
Alan,

You have a problem with the injector harness.  I would think that the relay for the injectors is hanging up.  I would check the voltage at the battery, with the key off, and see what the draw is.  Everything seems normal until the car is off and there is a great drain on the system.  Check each subsystem and find the drain and replace the effected relay.  That is what I would do to find the problem.  The alternator and battery seem to be fine.  But, when the car is off there is something taking the system down.  So, check it out and email me back with what you find.  Remember, only a hundred mili-amp draw is all you should have when the key is off...