Suddenly won't start

G

GAR64

Senior Member
29 Tudor suddenly won't fire. Was idling and just died. Now won't fire. New battery so it turns over great. I'm not much of a mechanic but I checked the following:

1. Connections on coil and distributor
2. Since I had the dash apart last week, I removed it and look at ignition connections.
3. Pulled wire off distributor and held against ground while cranking, saw no spark
4. Seems to be getting plenty of gas

No fuses that I know of. I am thinking it must either be the coil or the ignition switch??
 
coil would be the first part i would replace. pull out a meter or test light and see where the power stops
 
You mentioned holding distributor wire against ground and saw no spark. The distributor secondary wire should be held about 1/4" from a ground when cranking. If held against a ground, no spark will be seen.

If still no spark, then check for voltage at the moveable point arm while its held open and no voltage while its closed.

If no voltage at open point arm then work back thru all primary connections until voltage is found.

Don't replace any parts until the problem is found unless maybe changing the condenser with a newer 'short-proof' one.

Lets us know after trying to find voltage.
 
What Patrick said to the T... You mentioned about your ignition switch.. Make sure it is not touching the gas tank,, the after markets are famous for that,, insulate between the two..
 
Ok. I must admit I do not understand the wiring diagram I am looking at. I would really appreciate if someone explained how the ignition switch operates. I have no spark at the secondary (big) wire coming from the coil to the distributor. I do not understand checking for voltage at points.
 
I'm no expert for sure but will share my experience from last weekend. I participated in a show last weekend in Dublin, OH, we had about 30 A's in attendance, nice turn out. One of our members had the same problem, all of a sudden his car would not start. We had 30 "experts" (and they really are) at the show....they were trying everything already stated in this thread, nothing worked. One of our "old timers" and I say that with respect came over with a wrench and tapped on the carburetor a couple times.....the car fired right up.

No idea if that fixes your problem but thought I would share...

Nick
 
I would really appreciate if someone explained how the ignition switch operates.
Click to expand...

On a stock Model A system, when the ignition switch is on it completes the circuit from the points to the ignition coil.
The other side of the coil is always "hot".
With the switch on, when the points are closed you get a ground connection to the coil, when the points open that connection is opened and that causes the coil to produce the spark.

HTH
 

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Thanks Katy. So, Can I check for voltage on both sides of coil to determine if points are ok? With key on (not depressing starter) should I see 6 volts on both primary sides?
 
GAR64 said:
Ok. I must admit I do not understand the wiring diagram I am looking at. I would really appreciate if someone explained how the ignition switch operates. I have no spark at the secondary (big) wire coming from the coil to the distributor. I do not understand checking for voltage at points.
Click to expand...





The ignition switch on an A is a bit different than most ignition systems. All it does is turn on and turn off primary current [ low voltage] to the distributor [points].

Mitch makes a good point, as he always makes, about the replacement switches grounding against the fuel tank. Many times the terminals need to be 'warped' a bit and insulated from the metal tank.

To check for spark, remove the secondary wire [ high voltage] from the distributor, making sure the coil end is fully inserted, and place that end 1/4" from a good ground. Turn on the key and crank the engine. You should see a flashing spark from the coil wire to the ground. [You can also do this by manually opening and closing the points with the key on without cranking the engine.]

Checking for voltage at the points is done by removing distributor cap and turning engine over until points are closed. Insert something such as a piece of paper, or something insulating, between fixed and moveable point arm. Turn on key. Use a test light [ every Model A owner should have one] or a volt meter and see if there is voltage [ 6v] at the moveable point arm. If so, then remove insulator and see if there is still voltage. If there is then the points probably just cleaning, but, there is something not allowing voltage to go to ground as it should.

If there is no voltage at the point arm [when open] then work backwards thru the system until voltage is found and fix the problem between there and the points. Some times there is a problem where the primary wire screws into the distributor either with the connector or the insulation on the wire grounding to the sheath.

Try these and we'll see where you stand. Again, let us know.
 
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Bratton's, in his catalog, has a very simple wiring diagram indicating testing a Model A switch and distributor by turning one's key ON and OFF.

Testing the entire Model A DC electrical wiring system is so very simple.

Start at the source, the battery, for example, Point A, and read the voltage on a multi-meter between the (+) and (-) battery posts; and next follow each and every wire and test all wiring connections between (+) & (-) with the same multi-meter.

No different from reading a simple road map ..... problem is ???? ....... if one cannot read a simple road map from Point A to Point B ......... and one cannot read a simple multi-meter ............ this person will have great difficulty reading a Model A wiring diagram.

Moral of the story could be:

If one cannot read a Model A wiring diagram, just stay home ..... or hire an experienced chauffer prior to going on a very, very long voyage.
 
With key on (not depressing starter) should I see 6 volts on both primary sides?
Click to expand...

Yes, if the points are open, and there are no problems w/the wiring between the points and the coil.

BTW, I attached the Model A ignition wiring diagram to the above post (#7).
 
Don't do like most do when they don't understand a problem: start throwing parts at it. Look at the wiring diagram carefully and educate yourself on basic electrical principles. ANYONE can learn the basics, and then you will be armed with the knowledge for future issues as well. Shotgunning will only lead to more issues introduced. If you feel incapable, find someone to teach you or else turn the problem over to someone else. If you bring the wiring diagram and your car to any experienced mechanic, they will be able to fix it. The A is about the simplest of all cars.
 
Yes, Eagle I agree with you. I think I now understand and have a plan. I am going to check for voltage at the points. If there is voltage at the points, I will check for voltage at primary sides of coil. (points open). If voltage there, then I should see spark at distributor unless coil is bad. If no voltage at the points, perhaps the ignition switch is bad or grounding against the firewall. Have I learned anything? If I understand correctly, the ignition switch just completes the circuit. When the points are closed, the secondary circuit sends high voltage from coil to distributor.
 
Gar64, if you have a fuse mounted on the starter, check to see if the fuse is making solid contact to both clips. These new fuse holder aren't made with good spring clips. Remove the fuse and pinch the clips together with your fingers and then re-insert the fuse. Then check for 6 volts on both sides of the fuse.
 
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