1940 ford charging system

W

winchester

Junior Member
Hi. Took my 1940 ford on a 20 mile trip today, thought I had the charging system fixed. Put the car in the garage ,shut it down, did not have enough battery to turn the engine. Need some help on trouble shooting system. Thanks Winchester
 
Back in the day, I would start the car and let it run until it idles nicely. Disconnect the negative battery terminal. If the charging system is working correctly, the engine will continue to run. If it stalls, start at the generator and work backwards to the regulator, to the solenoid , to the battery and diagnose each connection and part.
 
Hi. I did what you told me and disconnected the ground on the battery, and the engine quit. I had the generator and voltage regulator in the shop they told me that both of them are working fine. What next. Thanks
 
Check the wiring at the voltage regulator. Tell us what you have connected to the three terminals. And voltage at each with the engine running if possible.
 
check your battery voltage at a fast idle.. you should have around 7.2-7.4 volts at the battery terminal on the voltage regulator and it may be a tenth or two less at the battery. It has to be fast enough to energize the regulator to charge.

If that is good and your battery passes a load test I would say you either have a ground problem or starter. I had a '47 coupe I was working on for one of our local guys and he had two of the new starters from one of the advertised sources... and they both did the same thing. I took one from my in process apart '48 coupe and put it on there and problem solved. So just know sometimes "new" doesn't always mean it works and is better.

Good luck!
Larry Shepard
 
Hi. I checked the voltage at th regulator the BAT was 6.24 the field was 0 and the arm was 2.24. Thanks Winchester
 
with the motor running try jumping from the A to F generator terminals. If it charges the regulator is bad. If no charge quickly short A terminal to ground if it sparks Gen OK reg bad. If no spark gen bad.
 
Hello all. I am having the same issues as Winchester with my 41 Ford running a 48 59 A/B and a 6 volt system. I hope he doesn't mind me joining this thread. If it is an issue, I can start one of my own.

With a fully charged battery and nothing electrical running, my meter is showing 6.7v at fast idle if I touch the probes to the battery connectors at the battery. I will go back and check it at the BAT terminal on the VR.

When I disconnect the ground (positive terminal) engine dies immediately. Is this the incorrect way to test? Should I have disconnected the negative terminal?

I also ordered a Ford electrical systems manual on eBay.

Advice is appreciated.
 
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