Expert: Brad Sears - 8/1/2009

Question
Good Evening Brad

another question on my 47 Ford Fire Truck with 6 volt positive ground system,I just reinstalled my generator and when I went to flash the field wire on the battery leg I noted no spark, however when I put the field wire back on its respective termimal I observed a spark, Using my multi meter I measured voltage on the arm side, so thinking I may have gotten my wires crossed on the Battery and Arm legs, I reversed them the generator powered up momenterly then stopped,at which point I tried to start the truck, it turned over, but would not start,however prior to me hooking up the generator the truck would run with out it, I have reached a dead end,have contacted several mechanics localy and they not being familiar with this type of system, I am hoping you can give me some light where to look next, start soloinois shorting, bad coil,wiring not connected properly ??? I have searched high and low for a wiring diagram for 6 volt positive ground system and can not find one. Your guidance would be greatly appreciated.

Thanks ain advance for your continued assistance

Steven

Answer
Oh boy, this is one of those cases where you need to be there. It is a 007 case of starting at the battery and checking each connection with a voltmeter. Remember that the A terminal on the voltage regulator connects to the A terminal on the back of the generator. The B terminal on the regulator is live all the time and connects to either the battery NEG terminal of the live terminal on the solenoid. The F terminal connects to the F terminal on the generator while the G terminal on the generator goes to ground. It sounds like you have shorted the regulator by connecting it backwards. It is possible that you spiked the electrical system and burned the points, coil or condenser causing the no start. The ignition system gets it's power from the ignition switch, then to a resistor under the dash up over the steering column. It is possible that this resistor took the hit if the generator system spiked and burned out. Again this is a voltmeter test job. Good luck.
Brad