No Start, HELP

Phred

Phred

Senior Member
I have been called in to help get a Model A running.
Car was running "when parked" 2 years ago, now has been towed to a garage.
Upon arrival: Dead battery (6v), Empty fuel tank, and Seized distributor.

Fuel lines were blown out and a few gallons of fresh gas added. CArb is getting gas as it drips out the air inlet when cranking with choke.

New 6v battery is installed.

Seized distributor was replaced with newly rebuilt complete distributor (from Model A vendor) that contains the original style points and condensor. Distributor properly gapped and timed.

There is NO SPARK when cranking. No spark when holding high tension coil wire to head stud, No spark when holding copper strap plug wire off of spark plug, no spark at points when slightly breaking the closed (new) ignition points.

There IS 6 volts at all points as shown on page 4-5 of the Andrews red Model A manual (Troubleshooting the Ignition System). There is 6 volts all the way to the points arm.

6 volt coil was replaced with no difference.

I am stumped. What else can be causing the lack of spark?

Other wiring somewhere?

Thanks in advance for suggestions.

Peace, Phred
 
About a week ago I put a set of brand new points in my car and the car would not start. I traced it to the points not making contact with each other. I initially sanded the points and cleaned the sandpaper residue with some cardboard. Later I took the time to hone the points with a diamond hone. That solved the problem. The points had apparently oxidized or picked up some contaminates from sitting in the box.

Turn the engine over until the points are closed then measure the resistance between the moving arm and ground. Or turn the ignition on and measure the voltage. The resistance should be very low, a fraction of an ohm, and the voltage should be very close to zero. If you are still getting 6 volts at the moving arm when the points are closed the points are not making contact. Clean the points using 400 grit sandpaper or a point file or a diamond hone then try again. Sometimes just rubbing the points together will do the trick. There usually is enough slop to do a little rubbing.

Do not leave the ignition on for more than a minute or you may overheat the coil.

Another thing to try is to short across the points with a screw driver when they are open and the ignition is on. This should generate a spark at the high tension output of the coil. If not then there is some electrical problem unrelated to the points.
 
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Make sure the metal tab on top of the rotor is bent up enough to touch the contact in the distributor cap.
 
Make sure the distributor shaft rotates when you crank it. If it doesn't, you've got a stripped timing gear - a possibility that is often overlooked.
 
6v at points arm when points are open, no voltage at points arm when points are closed.
Phred
 
Here is a good link....be sure to note one correction to the checklist...Correction to my post....

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"

https://www.fordbarn.com/forum/showthread.php?p=2022890#post2022890
 
Take a voltmeter and put ACROSS the coil terminals. Use a crank and slowly turn the engine over, when points are open you should have full battery voltage across coil, when points close you should have zero volts or VERY close to it. If that's happening, you'll have spark out of the high tension side of the coil.
 
This sounds similar to my issue a few weeks ago almost to the letter with your test results and it ended up being the bottom plate in the distro was grounded someplace or somehow. Put in a new bottom plate and also made sure the ignition switch was not too far in to push the old condenser tab against the housing body, ended up wrapping some tape around the tab as well.
 
If you get spark at the points, you should get a strong spark when holding the coil wire near a head bolt. With the points open, you can simulate the points working without turning over the engine by shorting the points contacts (key on) with a screwdriver which will trigger a spark at the coil wire and ground source. If this works, the only problem could be a film at the point contacts, or rotor troubles.
 
They're fairly straight forward circuits, so it's just a matter of isolating where the issue is. Assuming this is a 6V positive ground vehicle, I would start with the following.

- Disconnect both coil wires
- Connect negative lead of meter to black, negative wire coming from terminal block that previously went to the negative terminal of coil
- Connect positive lead of meter to engine ground at any point, verify +6V is read on meter
- If not seeing +6V, check ammeter and terminal block wiring
- If seeing +6V, connect positive lead of meter to red wire coming from ignition switch that previously went to positive coil terminal
- With points closed, ignition "ON", it should read +6V
- With points open, ignition "ON", it should read 0V

If it reads 6V all of the time, you may have a faulty pop-out switch (if original), or you may have a short in the ignition wiring running between the coil, ignition switch, lower distributor plate, or the wire/mechanism connecting the lower plate to the upper plate.

If reading 0V all of the time, there's likely a continuity break somewhere along that same path -- verify no wires are broken or disconnected and that your ignition switch works properly.
 
If, as you say, you are getting 6 volts at the point arm when the points are open and 0 volts when they are closed, but still no spark, there could be a couple of other things to check: I know you put a new coil in or otherwise I would recommend checking the coil. Check the high tension wire coming from the coil. Make sure it is inserted all the way into the coil. The little rubber boot can sometimes keep the wire from inserting correctly. Or it could be a bad wire (unlikely). But you may want to try a different wire anyway. If someone has used a modern carbon conductor they can go bad.
 
I had a problem with this and it was a bad ground
put a jumper cable from the battery ground to the bell housing
Dennis
 
hot wire it to help find the culprit
 

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DJ has a good point. Voltage is not current. If you have resistance somewhere in the system it could be restricting the current through the coil and not allowing it to saturate. Simple to check. With the points closed check the ammeter. It should read a discharge of about 5 amps. If not then it could be that the ammeter is not wired correctly or there is some resistance somewhere. Check all the connections. As DJ said check the ground side of the battery. Could be a bad ammeter. You can bypass it by jumping the two terminals on the junction box on the firewall. All things electrical are explained in this site: https://www.mafca.com/downloads/Seminars/2018 Reno Electrical System Alex Janke.pdf
 
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UPDATE:
The NO START problem was in the wiring (probably).

The port side terminal box stud was loose in the box and may have been grounding out to the face of the firewall, but wouldn't that blow the fuse on the starter?

Comparing the wiring inside the terminal box to the MAFCA drawing there were three of the yellow and yellow-black wires attached to the port side stud and only one of the yellow family wires attached to the starbord side. I rewired the two yellow-blacks to the port side stud and the two yellows to the other and also replaced the suspicious looking black wire from the terminal box and coil. This yielded spark at points breakage, strong arc out of the secondary wire of the coil, and a smooth running engine.

Thank you to all for your help.

Peace,
Phred
 
Very happy you got it fixed and thanks for the feedback. It is always good to know the solution to a problem. I suspect it was the loose connection or bad black wire since you were getting voltage at the points and not a short to ground which, as you say, would have blown the fuse.

You may want to go back and trace the wires you moved. They may have been that way for a reason. I hate mysteries and will investigate until I know how things are wired up. I draw a schematic and will sometimes label the wires with masking tape and a ball point pen.

Both sides of the junction box are at the same voltage, it is just that one goes through the ammeter. So you may not be reading the correct discharge and/or charge current now.
 
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