Engine dies in Friday evening traffic...

[Gaz64]

Originally Posted by Dangerous Doug

Cruising home from work on Friday evening, travelling up the infamous Hwy 17 from Silicon Valley toward the Santa Cruz coast. I get up the first hill just putting along and I'm next to the Lexington Reservoir when without warning my engine dies completely.

The traffic was pretty thick but I was able to coast my way to a wide area and stop. I've never run out of gas before, but my needle was a little low. Popped the air cleaner off and checked for fuel. All is well.

Hmm, electrical then? I ponder the situation a bit, then get my tool box out of the trunk and dig out my trusty DMM. I turn the key on and check the voltage on the + and - sides of the coil. 12 Volts, both are positive.

My coil has failed.

I've been down this road before, only with a Volvo. I let the engine cool a bit and once cool, fires right up. I'm able (stressfully, very few turn outs or wide spots in the road) to drive home over the hill, and then I go purchase a new MSD Blaster 2 coil at the local shop.

So, when I installed this engine I purposely had a friend machine a coil bracket for me which holds the coil straight up, as the Blaster 2 is oil filled. Anyone else have issues with the Blaster 2? This one only lasted 4 years, and almost left me stranded.

Glad I had that DMM in my trunk! I saw four other cars on the side of the road as I drove home, each of which the very tired looking drivers waiting for a tow truck!

DD

Key on, engine off, you will have 12v both sides of the coil if the distributor "switch" is off.

[Dangerous Doug]

Originally Posted by Gaz64

Key on, engine off, you will have 12v both sides of the coil if the distributor "switch" is off.

I was going to call you on this one, but I thought it wise to go check, first.

You are correct.

I had a Volvo with a bad coil. Nobody could figure it out. I measured the voltage on + and - when it was running fine and then drove it around until it died on me. I checked the voltage at the + and - and found it different from earlier. Replaced the coil and the problem never returned.

I am convinced the coil was bad on my Cobra, as it acted the same way (drive around until the coil gets hot from the engine, it either shorts or opens causing the engine to die, the engine manages to cool after some time, the short disconnects or the open closes with the cooling, and off you go).

I wonder if it had a chance to cool from when I opened the hood until I could get the DMM out of the tool box in the trunk and make a measurement.

Okay, so my test was bogus, but the assessment correct.

So, for future reference: How do you properly test a coil in the event of a failure?

DD