Starting Problem - electrical

C

Colonel Biggs

Senior Member
I have gone through two ignition coils in the last two months. I am driving a '31 Roadster, and out on the road (naturally, never in the garage) the car will crank after a stop, but fail to fire. The system works perfectly up until that point. Then, no spark from the coil to the distributor. It has not cut out while driving, but only after driving a few miles; stopping, and attempting to restart. When I have installed the replacement coil, the engine fires right up. On the failed ( ? ) coil, I do still get juice to both sides of the coil.

I have been using the upper distributor plate with modern points and condenser. I have put so few miles on the car that I have not tried changing out the condenser. But, if the condenser were faulty, would it even work with a new coil?

Very frustrating!

Gordon Biggar
Houston, Texas
 
You describe the classic temperature problem. Either the condenser or coil are failing when hot. Since the condenser is the least expensive item and you have not changed it, try it first. When you stop after driving, the heat saturation of components goes way up!
 
Are you sure no spark, or that it just doesn't fire up?
Have you checked for a spark at both the points and by grounding the coil wire, then the spark plug connectors?
A big question is whether it is a lack of fuel or fire that prevents it from catching.
Are you getting fuel?
Is there a spark from the connectors to ground when turning over the engine?
Don't just start swapping out parts until you have determined the culprit.
 
Bruce Adams said:
Don't just start swapping out parts until you have determined the culprit.
Click to expand...

This is a very common problem a lot of people make. A lot of time and money is wasted changing parts without first understanding what the problem is.

The Model A is actually a very simple car to work on. If the basic engine is in good working condition, all that is needed is "Fire" and "Fuel" to make it run. By far most of the time if the car was running and just quit, It is usually just an ignition problem or not getting any fuel.

If the engine is not getting fuel it is almost always a restrictiion in the fuel supply. Dirt, rust, plugged filter, out of gas (don't laugh, it happens) etc. Carburetors are basically mechanical device that usually will not quit all of the sudden and usually the float sprung a leak or the choke linkage became unhooked.

It has been my experience when the engine has been running fine and you loose spark, it is almost always either the condensor or the points have closed up.

Les Andrews has some very good information in his books that help with diagnosing problems. The more you know about the basics of your Model A, the more comfortable you will be going places in it and enjoying it.

One problem with just changing parts is you are never really sure what actually fixed the problem.

Again, Just my opinion,

Let us know what you find out,

Chris
 
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Thanks for the posts. Further digging, which I had hoped was not necessary, indicates that juice is not getting beyond the pop-out switch to the distributor. This is an original that was rebuilt some years ago, and never has given me a problem. On the first coil to go, I did have juice at the points, and I assumed (I know, never assume) this time around that I would have juice there again.

I don't look forward to having to pull the switch for a rebuild, but at least the source has been identified. Many thanks for the time taken by those who posted.

GGB
 
There are TWO types of people IMO, those that understand electricity from birth and those of us than can not. RARE is the electrically knowledgeable that can explain it, NO TWO elictrical knowledgeable people will give you the SAME answer. Whatever the explanation is a BRAND NEW term will be added to the explanation that drives the electrical idiot to the dictionary. Dad's Roadster died in 1983, and it isn't fuel that keeps it from running. Someone should explain in SIMPLE terms how ONE PERSON on his own could test to see how the electricity works to get an A to run. 1 Buy test light,.......then what?
 
Dear Mr Roadster 62

Did you read my recent article in the RESTORER magazine? Did I miss something?

I can send you the article.


Dennis L Oberer
Green Bay WI
 
Gordon,

I had this problem several years ago on my car.
Question: First you have the modern points and condensor on the upper plate and no condensor on lower plate ... right?

If so remove the upper plate and look closely at the lower plate. I think that you will find that the tab that normally would be hooked to the condensor on the stock plate is bent out straight and is shorting to the distributor body.

Problems were backfiring, stalling, dieing then starting right up after short time, changing parts seemed to fix then it came back. Also a random popping noise from inside the dist at idle and random sparks coming from dist advance slot at night and rough idle.
Hope this helps.
 
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Roadster62 said:
Someone should explain in SIMPLE terms how ONE PERSON on his own could test to see how the electricity works to get an A to run. 1 Buy test light,.......then what?
Click to expand...

I posted this before for someone that could not start his car, I hope it helps answer your question. I don't like a test light because it can glow with a voltage lower than what is needed for the car to run. Get a cheap meter. That is not to say that a test light won't work!!

1) First make sure the horn or lights work, you may just have a blown fuse,(assuming you have a fuse in the circuit).

2) With key off check for voltage on both sides of coil. Both should be hot.

3) Now, turn the key on and make sure the points are closed. You should have voltage at only one of the posts on the coil. If you do have voltage at both points, then the points are not closing to ground or you have an open wire to the top plate.

4) Check voltage to points, if you have voltage at the movable arm of the points, Move the spark lever in cab to close points or file points.

5) If no voltage then remove Condenser and check again.

6) Still no voltage, check the plunger on the armored cable under the top plate. Check the wire from the lower plate to the upper plate. Repair as needed.

6) If the wiring to the points check out, (No voltage at points when points closed voltage when points open) check coil.

7) Remove the wire from the center of the dist cap and place within 1/4" from a ground. Open points with screwdriver. You should have a good blue spark with a loud crack.

8) Place wire back back on cap. Remove one spark plug wire 1/4" from plug. Try to start car. You should see spark jumping to plug, repeat for all plugs.

9) If not, the problem is in the cap, rotor, or dist body. Check the rotor for rotation, and gaps from rotor to stubs inside the dist body.
 
Roadster62 said:
Ok, so I buy a NEW Cap all four plug "wires", condenser, coil, spark plugs, what else?
Click to expand...

Before spending money on parts you should check to see which part is bad. If your method of checking is changine parts, then change ONLY ONE part at a time, so you don't introduce new problems, as often happens when several parts are changed together.
 
Wirediagram.jpg


Headlite.jpg


43ee3c97392c01aa3af582f5bfa099010_l.jpg


WirediagramBody.jpg


ohms-law.gif


From Les Andrews shop manual, 1929 owner's manual, my 6 v alt, Ohm's law.

So I'm thinking something is moving and expanding with heat and going to ground.
It's all been well covered by others in this thread.

At our Spring Clinic we were shown a cheap aftermarket set of points where the spring and copper conductor would 'flutter' so close to ground at slow speeds the spark jumped to ground and created a miss fire. At higher rpms this did not happen...imagine that.

skip.
 
skip said:
Wirediagram.jpg


Headlite.jpg


43ee3c97392c01aa3af582f5bfa099010_l.jpg


WirediagramBody.jpg


ohms-law.gif


From Les Andrews shop manual, 1929 owner's manual, my 6 v alt, Ohm's law.

So I'm thinking something is moving and expanding with heat and going to ground.
It's all been well covered by others in this thread.

At our Spring Clinic we were shown a cheap aftermarket set of points where the spring and copper conductor would 'flutter' so close to ground at slow speeds the spark jumped to ground and created a miss fire. At higher rpms this did not happen...imagine that.

skip.
Click to expand...

WHOA Skip, how's the air going to blow through the radiator with the big ugly aluminum thing in the way? :) LOL
 
Yep and...AND it's a 'Delco Remmy' thingy too boot.

Cool thing about it, aside from blocking wind is one wire in and same wire out...so how do they do that?

Must be in the bridge rectifier of diodes. Half diodes pass the + ground~that would be the 'out' wire? and half pass the - ground~that would be the 'in' wire? since we need power 'in' to energize the alt to make juice for the car's electrical system. Or not?

skipster.
 
skip said:
Yep and...AND it's a 'Delco Remmy' thingy too boot.

Cool thing about it, aside from blocking wind is one wire in and same wire out...so how do they do that?

Must be in the bridge rectifier of diodes. Half diodes pass the + ground~that would be the 'out' wire? and half pass the - ground~that would be the 'in' wire? since we need power 'in' to energize the alt to make juice for the car's electrical system. Or not?

skipster.
Click to expand...

Well, that's another bad thing about the one wire alternator. They have a small parasitic drain even when turned off. That's why guy's that use them also install a fuse and pull it when the car sets for any length of time.
 
I'm fused but I have not pulled it for winter storage ever. Nor ever charged the battery in the winter storage. About 6 months.
I'll be pull'n next storage season. Thanx.

skip.
 
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