Still having a problem running smooth with lights on

[Bobant]

I can not figure this out. Car runs great with lights off. Lights on ,car starts to run very rough. Just put new battery in and problem still exists. Take all bulbs out and turn lights on and no problem. I assume that means no shorts. As I put bulbs in car starts to spit and sputter. The longer I run the brake lights will make it stall as I approach a stop sign or red light. The only thing left is the generator I guess. Gauge in car says it's charging at 10 amps when running 25 and above. At idle it's at zero. If I hit the brakes immediately goes to minus 10. I'm stumped. Any ideas?

[J Franklin]

I have a 1936 non Ford car that does similar. New batt. new wiring, good grounds, & Etc. I'll be watching this thread.

[Chuck Sea/Tac]

If you put any bulb and it will do that? Or do you have all the lights in and it does it? What I'm getting at is do you have a short in the socket when it's compressed with a bulb? When you put bulbs in ,is the switch on. As you said it sputters when you do this?

[Mike V. Florida]

How old was the battery you took out?
Have you checked the voltage at the cutout with and without the lights on?
I'm thinking generator and or ground problems.

[RonC]

Try cleaning the ground cable connection at the battery and at the frame.

[JOHN CT]

Sponsored Links (Register now to hide all advertisements)

sounds like a bad ground to me . Did you try 1 bulb at a time? What helped me with ground problems was adding a second ground wire from battery to starter amazing it runs like a 12v system

[Kurt in NJ]

Your charging amps, discharges seem normal, what are the voltages ---at the battery, at both sides of the coil---with the points open, and with the points closed----is your ignition system stock ---ie --popout, wiring, coil, points/dist, with a stock system one side of the coil should have near battery voltage, with the points open both sides of the coil should have battery voltage, with the points closed one side near battery voltage---the other side 0---if you have voltage of 0.5 volt or more there is a problem between the coil and ground (wiring to popout,popout,dist lower plate/wire,points,dist ground.) ---

Have you tested the spark, how far will it jump, compare with ,without lights

[Tom Wesenberg]

Kurt has pretty well covered it. The first thing I would do is check the voltage on the coil primary black wire terminal, which is the feed wire. The red wire should lead to the switch and then to the points and ground. Check the voltage with the engine running at fast idle (700 RPM to 900 RPM) , then again running with the lights on. The coil voltage comes from the terminal box post, and both the battery and generator should be able to supply the needed voltage, so my first guess would be a poor connection at the terminal box. Remove the nuts and wire terminals, make sure they are shiny clean, and reinstall then nuts. A dab of grease will help keep corrosion away.

Since the battery starts the engine fine, I wouldn't think the posts or ground connection there are a problem.

Are you running a completely stock ignition system?

[Bobant]

Finally success. Opened up the terminal box on the firewall. Cleaned all connections even though they all looked reasonably clean. I also noticed that the coil had some brown staining on it at the bottom so I changed that also. Took the car out for a 20 mile ride and everything worked the way it is supposed to. Brake lights on, no stalling. Head lights on , no stalling. Not sure what fixed it, either new coil or clean connections. Thanks all for the great suggestions. You guys on here are a life saver or model a savior.

[Mike V. Florida]

Originally Posted by Bobant

Finally success. Opened up the terminal box on the firewall. Cleaned all connections even though they all looked reasonably clean. I also noticed that the coil had some brown staining on it at the bottom so I changed that also. Took the car out for a 20 mile ride and everything worked the way it is supposed to. Brake lights on, no stalling. Head lights on , no stalling. Not sure what fixed it, either new coil or clean connections. Thanks all for the great suggestions. You guys on here are a life saver or model a savior.

Yes, Poor connections cause a loss of voltage as you increase the amount of electricity used. Add to that a coil that is failing and needs all the voltage it can get and your are asking for failure.

For laughs have you checked the voltage at the terminal box with the engine running, with and without he lights on? It should read real close to the same.