multiple electrical questions

[Tarheel Tom]

I just replaced a broken water pump on an A model that was previously running fine. The battery was corroded and dead so we also replace the battery and the cables. Not sure if I got cables specified for six volts. Ground cable was not braided as original. used same frame bolt.

Starter turns over briskly , but no spark at points or from the coil when aimed at a head bolt. I have perform diagnostics with a voltmeter and everything seems to check out with 6.4 readings...at the starter, at both terminal bolts, both sides of the coil and at the distributor with ignition "on" and gap insulated.

Coincidentally, no lights or horn.....Cowl lights came on for a second and then out.

Is this related to the new ground set up. Can you get voltage readings if you don't have a good ground connection?

Puzzled novice.

[Jim/GA]

An electric schematic diagram has been supplied on the FB several times. Do a quick search. They are also in books, like the Model A Mechanic Handbook. Start with that and trace things out.

If you are cranking well, that means you probably have a good ground. Cranking takes the most amps.

Does the car have a fuse added to the yellow wire that comes off the starter switch? Lots of people add them. It might have corroded clips. They are notorious for causing intermittent electrical problems. That would impact lights and ignition, not cranking.

Are the ignition points corroded? This is a common problem when a car sits a long time. The condenser can also be bad from age. You don't say how long it sad without being run. (Long enough to kill the battery.)

Make sure the coil wire is pushed up snug into the coil.

[sethkestenbaum]

Tom, I'm living the electric gremlin dream as well. My electrical system has some issues. If you have the Bratton's catalog, page 94 has a GREAT illustration for the wiring. Some of the tables leave confusion as to which side of the junction box is which.

[Tarheel Tom]

The A model (31) sat for about 5 years after the busted water pump. Nothing else was changed re electrical until i replaced the battery and cables. I really expected it to roar to life when we started cranking. When nothing happened, first thing I checked was the spark from the coil......since then I have used diagrams from FB to trace every step of the circuit.

I will check for a fuse, but I don't think it has one. It does have a new style upper plate. in the dist. maybe the points and condenser need to be replaced.

the light problem must be unrelated if I don't have the fuse added.

[Mitch//pa]

Clean and adjust the points. You will get 6 v on both sides of the coil points open
Points closed KOEO the points should ground and then you'll have power on one side of the coil...
Again try cleaning the points

[Chuck Sea/Tac]

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I'm guessing you have two problems . The lighting is probably corroded at the main lighting switch at the bottom of the steering column.

[Tom Wesenberg]

I agree with Mitch to clean the points. To check this out just stop the engine with the points OPEN, then turn the key on and short the points off and on with the tip of a screwdriver while holding the coil wire 1/4" from a head nut.

[Tarheel Tom]

will do on Sunday...and report back.....Thanks for the guidance..hoping for fire.

[BILL WILLIAMSON]

Originally Posted by Tarheel Tom

will do on Sunday...and report back.....Thanks for the guidance..hoping for fire.

Tom,
Take heed to Tom & Mitchs' advice, THEY KNOW THEIR STUFF!
Bill W.

[mshmodela]

Wondering if you have weak battery.... In addition to the above, check each cell and clean the ground at the frame and the battery (It can only help)...

https://www.youtube.com/watch?v=SFqgDPzEau4

[Patrick L.]

Regarding checking for power at the points when open and none when closed, I agree. Cleaning the points is a good thing. One other that hasn't been mentioned is which modern upper plate you have. The earlier wireless have been know to be problematic so check for continuous continuity between upper and lower as you just might have an intermittent problem. The later units use a fine strand wire.

[katy]

If you're testing w/a digital meter it can show good voltage when you have poor connections. Try testing w/a test light.

[ian Simpson]

Originally Posted by katy

If you're testing w/a digital meter it can show good voltage when you have poor connections. Try testing w/a test light.

I agree with Katy' you need power (amps) not just volts. Use a big headlamp bulb in a test light to confirm that you do not have a high resistance connection in the circuit.