Model A no spark
 

My 28 A arrived yesterday and started to back off fine. An hour later no start only turn over.Tried the coil wire to head. No spark. Tried a known coil that is good. No spark. New wiring. NOS amp meter. Can anyone help ?

Re: Model A no spark
 

What type of switch popout etc? all connections tight.

Re: Model A no spark
 

Start here. Open and close the points. No spark check the distributor wiring and condenser! With paper between points check to see if you have voltage on the movable side and ground on the fixed side. If you do move to the terminal block on the firewall and check for voltage readings.

Re: Model A no spark
 

Here is a copy of a post Mike V posted. Please read the entire post.....If it is the junction box ...should be power on both sides. If not the Amp gauge is bad. Jump across the two lugs of the junction box to bypass meter....


Senior Member

Join Date: Oct 2014
Location: Central New Jersey
Posts: 174
Default Re: Coil problem?
Mike V Florida has posted this and I think it's wonderful:

This is my generic no spark troubleshooting list,

No Spark
Some possibilities are:
1.Blown or defective fuse (use of a fuse is an aftermarket item)
2.Bad connections at ammeter, or ammeter itself (t0 find out put a jumper wire from one post of the terminal box to the other to take the ammeter out of the circuit temporarily)
3.Bad ignition switch and/or cable, or loose cable connection at the switch.
4.Loose or broken wires at bottom of coil
5.Loose or broken wires inside terminal box
6.Loose, bare or broken pigtail wire under distributor plate, or wire grounding to plate or distributor body
7.Points not opening, or point arm grounding to cam due to worn rubbing block
8.Worn electrode in underside of distributor cap
9.Loose or broken high tension wire from coil to cap
10.Condenser burned out or grounding (some condensers are too long and can touch the distributor body inside)
11.Weak coil
12.Rotor not turning due to loose cam screw or bad timing gear.


Ok now break out a volt meter (a light bulb can give false readings).
Start at the fuse block, you should have voltage on both sides of the fuse. If you only have voltage on one side, replace the fuse or fuse block.

Now with voltage on both sides of the fuse, move up to the junction box. There should be voltage at both terminals. If voltage is present only on one side the problem is at the ampmeter and you should Jumper the ampmeter for now.
You should have voltage on both sides of the coil. If not,
remove the red wire on the coil and check again. If you now have voltage on both sides, you have a problem further on. If the voltage is still only in one side you have a bad coil.

Open the points with a piece of paper and remove the condenser. Turn the key on and you should have voltage at the points.
Replace the condenser and you should still have voltage.

If the voltage is missing, remove the top plate and check for voltage on the bottom plate.

Check if the connector from the ignition switch screwed in too far? Do you have voltage on the wire to the upper plate?

Is this wire shorting to ground or broken?

Remove the paper from the points and see that the points are closed. You should not have 0 volts at the points. If you do, the points are dirty or the distributor is not grounded well to the engine.

Re: Model A no spark
 

After doing the steps outlined above in #4, please let us know what you find.

Re: Model A no spark
 

Check to make sure the points are opening properly. Poor point blocks will wear down and then the points won't open. Lube the cam too.

Re: Model A no spark
 

Do you own a VOM.

Re: Model A no spark
 

Sorry, but I'm having trouble with the last paragraph of the above trouble shooting list. Am I confused?

Re: Model A no spark
 

You are removing the piece of paper from the points that you put their to hold the points open and not make a connection. That is part of the testing procedure to see where all of the electrical connections are and which are functioning correctly.

Re: Model A no spark
 

I think there is a mistake a typo...I believe the following is correct

With the points open (paper inserted) there should be battery voltage at all times. With the points closed ( no paper) there should be 0 volts at all times. [ key on].

The posted "you should not have 0" ...I believe should read "you should have 0" .

I did cut and paste the post, perhaps Mike V can join in and clarify...or any others who know a lot more than me! Thanks. Sorry if I spread the wrong info....

Re: Model A no spark
 

https://www.fordbarn.com/forum/showt...olts+key+on%5D

Read # 6 and then 7 of the attached thread.... Points closed 0 volts would be correct.

Re: Model A no spark
 

get it figured out?

Re: Model A no spark
 

Hi guys new here and thought I’d resurrect this thread since I’m having the same issue and have done all of the above with no success.

A little backstory on this one; 1931 Model A Tudor all stock, ran like a champ until 2 weeks ago. Was cleaning it and apparently the two wires going into the horn (were not hooked up) got jostled around and laid against the back of the headlight (I didn’t catch it) and it arced and burned up the wiring to the headlight and the horn. Easy enough to replace, no super concerned with that BUT the car will no start. It’ll turn over just fine but it’s got no spark; almost as if the car has no power throughout the system.

I’ve done all the tests as outlined in #4 and I am baffled. Any help would be greatly appreciated. Heck, if there’s anyone in the Fresno, CA area that would be willing to help me out, I’d buy you lunch (or dinner)!!

Re: Model A no spark
 

If those wires burned up that badly, the wires from the terminal box to the instrument panel most likely are also toast. If they look the least bit blackened or feel crispy, replace them. All the ignition juice runs through those wires, so they cannot be compromised. Pull the terminal box cover off and the instrument panel forward to inspect the wires for signs of overheating and loss of insulation.
Marshall

Re: Model A no spark
 

Do you have power at both sides of the terminal box?

Re: Model A no spark
 

Bob: yes, I do have power on both sides of the terminal box

Marshall: I haven’t looked under cover of the term box but wires under the instrument panel look good; no chat whatsoever. I only lost about 6” of wire on the lights and the horn. I’ll pull the cover and report back.

Re: Model A no spark
 

The ammeter and ignition switch should be tested under current. Sometimes voltage will pass with no current but high resistance will block the voltage when there is any current. Lots of things to test. Just go through the wiring with a multimeter while the ignition is on and points are closed.

Re: Model A no spark
 

Easy first step...put a jumper between the two posts on the terminal box...this bypasses a bad amp meter.

Re: Model A no spark
 

Jumpered terminal box but nothing has changed. I did discover, I have voltage on either side of the fuse with the key in the off position but lose voltage when the key is in the on position. Seems weird or is that my issue. I’ve tested and swapped fuses so I know they’re good. But could the fuse holder be bad?

Re: Model A no spark
 

I’m losing power at the points. Got power at the terminal box, both sides of the coil and bottom plate of the distributor. Open the points, and I got nothing with and without the condenser (condenser is brand new too). Are the points toast or is there something else causing it?