[Healeys] Car dies suddenly

[Elton Schulz]

Michael,
Could it be the battery cutoff switch in the trunk or the black/white 
wire from that switch to the distributor?
Elton
On 3/19/2019 1:45 PM, Michael Oritt wrote:
> Yesterday morning I went out for a drive and after about five miles 
> the car suddenly died. There was no rough running, sputtering or 
> missing leading up to it---the car simply died. I coasted to the side 
> of the road and after about 30 seconds since the key was still on I 
> pushed the start button. To my surprise the car started immediately, 
> revved freely and idled smoothly. A bit perplexed I decided to drive 
> on to see what would happen now that I was paying close attention. The 
> car accelerated smoothly and ran fine for about 1/2 mile and then it 
> died again in the same manner as earlier. I shut off the key, popped 
> the hood and examined the ignition system. Everything seemed 
> fine---all spark plug leads were firmly in place as was the lead from 
> the coil to the distributor. The power wires to the coil were tight 
> and the harness/connector to the distributor (see below) seemed fine.
>
>
> After scratching my head for a couple of minutes I got in the car, 
> turned on the ignition and pushed the start button. Again, the car 
> started right up and ran normally. With fingers crossed I headed for 
> my shop/garage, about ten miles away and got there without any further 
> event. Though the problem did not seem to be fuel related I decided to 
> verify that this was not a fuel delivery issue. I have a double-headed 
> SU fuel pump wired to a switch mounted just behind the driver's seat 
> which allows me to switch between pumps as well as turn the fuel pump 
> off. While I was running the car at highway speeds it ran perfectly on 
> either pump and when I selected the "off" position it slowly lost 
> power as I expected it to---but in no way like it had suddenly twice 
> died 15 or so minutes earlier. This indicated I was not dealing with a 
> fuel issue but rather something related either to the ignition system 
> or to the primary wires that run to it.
>
>
> This morning I dove a bit deeper to try and diagnose the problem. The 
> car has a Mallory Unilite ignition system tied to an MSD coil which 
> has been in place and performed faultlessly for a number of years. I 
> removed the distributor cap and everything appears to be okay, at 
> least visually. The interior of the distributor was clean and dry as 
> was the cap, leads, carbon contact, optical reader, etc. Mallory 
> specifies the use of a ballast resistor in the lead from the power 
> source to the coil and with the engine fast-idling I tested 12.5 VDC 
> to the resistor and about 5.5-6 VDC out of it and at the positive coil 
> terminal.
>
>
> I have a large low-oil pressure light that is mounted in the dash in 
> place of the original overdrive switch. It is wired from the ignition 
> switch through a 10 psi normally-closed switch mounted in the oil 
> pressure gauge sender line and then to the light. I point this out 
> because both times when the engine shut down yesterday the light 
> immediately came on, from which I conclude that the ignition switch 
> itself is not the source of the problem. And though I did not remove 
> the ignition key switch the wires to and from it seem tight and intact.
>
>
> So my question is: What do I do? I hate to throw parts at it without 
> finding something that appears to be defective but I don't know where 
> to start any further tests, etc. I also don't want to simply wait for 
> the issue to happen again. BTW over the weekend I drove about 150 
> miles with no issues whatever. Beyond installing four new plugs last 
> week I have not performed any work related to the ignition system. All 
> suggestions/questions welcome....
>
> Best--Michael Oritt, BN1
>
>
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