The Stovebolt Site Forums The Shop Area The Electrical Bay Engine Dead

Looking for some direction on where to start my troubleshooting on this one. I was driving my ‘51 half ton yesterday and the engine died, tried to restart and the battery was gone. Tried to jump, engine turned over but would not start. Truck was in a high traffic area so I had to get it towed home. Engine is a ’55 second generation 235 and all 12 volt elec items were transferred over with it - coil, distributor, generator, voltage reg. Battery is brand new, gas tank is full. I’m thinking that the voltage reg is the culprit but thought I should be able to jump start even if the voltage reg went bad. Also can I trouble shoot a voltage reg with just a standard voltage/ohm meter? Thanks much.

While searching the forums I found one item that I may have missed when converting from 6 to 12 volts and that is the ballast resistor, this has not been installed.

regulator won't keep it from starting, check the ignition circuit, make sure you're getting spark, might have fried the points or damaged the coil

Bill

Thanks Bill, waited for the battery to charge and started checking voltage, no voltage going into coil. Started tracking down that issue and found that the power wire going into the ignition switch came loose. That was an easy fix so we're running again but that does not explain the dead battery. I don't have an ammeter so I can't check the voltage reg but I pulled the cover and the voltage reg looks very new, that does not confirm it is set up properly however. I may have the generator tested first to make sure that is ok.
Mark

A simple check it to remove the positive terminal to the battery when the truck is at about 1100 rpm. If it continues to run when the engine is revved up, the generator is doing what it is supposed to do.

Here's a LINK that I have for understanding the electrical system.

Pulling a cable is a very risky way of checking the generator output. It's a lot simpler to ground the Field terminal at the generator and see if the voltage rises when the engine speed is increased slightly (the lights get brighter). Don't overdo it- - - -I've seen a 12 volt system go above 20 volts with the field grounded with only a moderate increase in engine speed. Pulling a battery cable can result in a voltage spike of around 100 volts in some cases. I've seen it on an oscilloscope several times.
Jerry

I wouldn't continue to drive it without an ammeter. You probably would have seen some trouble coming if you had a working one.

Thanks for the info sheet on the charging system, great to have!

To clarify my early post-truck does have an ammeter gauge in the dash, the ammeter I was referring to was the one in the service manual with the four leads, thanks.

Jerry, I'm going to give this a try. If I want to put a meter on this to check out voltage increase, where is the best place to check?
Thanks,
Mark

You can check it at the battery.

Kurt

all you have to do to see if your charging is put a volt meter across the battery, it should read about 12.6 volts not running and running you should see somewhere around 14 volts or more. if your regulator is bad it will be very high probably above 16 volts.