Electrical Gremlin ?

DennisR

DennisR

Senior Member
Just when I thought I`d cracked it, after nearly 2 years of learning from this forum thought I was well versed in the Model A idiosyncrasies but no.......
For the last year or so it has been starting on the button, until this morning.

My usual procedure, ignition on, fuel on, check retard, choke and hit the button, as soon as it fires choke in and a little advance. This morning it fired but didn`t run so I tried again, nothing, turns over but doesn`t fire.

Spent the day doing all the checks, changed the points, changed the condenser, changed the coil. checked the voltage at the junction box, coil wires etc., all showing 6+ volts except the points only showed around 2 volts, also no spark at the points or plugs.

What have I missed ?

By the by I am using a new off/on ignition switch
 
Check the pigtail wire connecting the lower plate to the points. Might be frayed or broken.
 
Make sure it isn't grounding out anywhere. I've sometimes had to bend the flag connector to increase clearance between it and upper plate.
 
You have to have 6 volts at the movable point arm when the points are open ane the key is on. Should have confirmed that before all the new parts.
 
DennisR said:
Just when I thought
Spent the day doing all the checks, changed the points, changed the condenser, changed the coil. checked the voltage at the junction box, coil wires etc., all showing 6+ volts except the points only showed around 2 volts, also no spark at the points or plugs.
Click to expand...

When you have a problem, NEVER try to fix it by replacing parts. Troubleshoot the problem, then fix it. You're soon going to have so many introduced issues you won't know where to start.
 
Ok, 2 volts at the points. Is that with the points open or closed?
Original popout or no?

If the voltage does not go to zero with the points closed the points are dirty.
If the voltage is only 2 volts when the points are open and you have 6 volts on both terminals on the coil, then your cable is bad to the distributor and/or the ign. switch is bad.

Here is a link to a simple diagram;

https://www.vintagefordforum.com/filedata/fetch?photoid=901
 
Thanks for all the replies. I did check for fuel, that was my first port of call. I then checked the voltages and replaced each item as I went. I missed out on the lower wire in the distributor as I had recently fitted a new ignition switch to replace the Spanish pop-out, and as it had been starting with no problems it didn`t occur to me that could be at fault. From your replies it looks like that is where the problem lies.
I checked the points with them open, a piece of paper between them.
 
:o Problem solved, I`m using a modern upper plate, the tab on the bottom plate which the original condenser attached to was shorting out, the insulation had worn, I cut it off and that sorted it, not shorted it :D
 
No longer original but I discarded the lower plate and connected the input directly to the modern points.
 
Dennis don't feel bad we have all been there . And no one has X-ray eyes yet. I had a similar problem after new new build but mine was extremely dumb problem . I did not even install the points no wonder it would not start. I was so embarrassed when the customer asked why what all of the questions when he showed up unannounced when we were trying to start the engine for the first time. Then he asked about did I check the points,and before I could answer he popped the cap. I could have crawled under a thimble. I am sure he wondered what kind of job he was paying for. But that truly was the only issue. New points that sucker fired up and ran like a scalded dog. It was a Dohc 427 ford for a cobra kit car. Fastest thing I ever rode or drove , I swear it would have scared god himself.
 
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