Loss of spark

[jddevel]

Drive it day threw up a problem which I`ve 2 weeks to resolve before a planned tour of South and wet Ireland. So the problem is the loss of spark. The story so far. After the Isle of Man national I started to have a back fire both through the exhaust and the carbs. With a "challenging" tour shortly after with the coil getting hot and breaking down I finally having ended up like a headless chicken on my return to the UK taking my dizzy to the Distributor Doctor where by chance it was discovered that a condenser which tested OK on the bench came apart in "the Doctors" hands. Hallelujah problem solved and a further tour to France uneventful. BUT today a recurrence of the same problem. Misfiring before finally dying. Hot coil. So change coil. Change condenser and off we go. Oh no. About 15 miles on same problem. More headless chickening. Change back to original coil and condenser clean up lead terminals -coil to dizzy away we go. So in order to leave for Ireland with a bit more confidence I`ve to make sure I`ve solved the problem Where would you start? Is the engine earth strap likely to cause the recurring problem. Can the cutout terminals. Where is the unseen resistance likely to occur on the assumption that that is causing the coil over heating. Any advice please.

[Steve Simmons]

So you put back parts that were giving problems before and now they're working?

First thought, I would never trust that a new coil or condenser is good. If you have a known good used spare, I would try that. You might want to test the resistance of the coil when cold, and then again when hot. If there is a significant difference then the coil might be on its way out. I had three bad Q12 coils, one dead out of the box, one lasted 250 miles and another 50 miles. I put my trusty old spare back in and it's gone another 10,000 miles without issue. Condensers are even more flaky although the ones from Distributor Doctor are pretty much rock solid.

Second thought, are you sure it isn't a fuel delivery issue? It isn't uncommon for the intake screen in the fuel tank to get blocked by rust scale or other debris. When you shut the car down for a while, the debris slowly falls away and everything is fine again for a while until it happens again. I've watched this happen to several people over the years.

[Rob Reilly]

On another forum I am on, a person reported hot coil and erratic ignition after the car was warmed up, and it turned out to be poor contact at the spark plug wires inside the distributor cap, in other words a gap or resistance in there.

[EdCallo]

With the condensers available today it is not uncommon to have a new one fail within 15 minutes.

Ed

[Tim Jackson]

Check this 'ignition coil heating up' post about a year ago:
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