Engine dies while driving - tach drops to zero (MSD)

[Tom Wells]

Adam,

This may not apply to your immediate problem, but may bite you again in the near future: I notice you mount the coil to the engine.

If you want the coil to be reliable, get this one: MSD Blaster High-Vibration. It is epoxy-filled and will last much longer when bolted to the engine. The heat combined with the vibration of the engine will kill a normal oil-filled coil fairly quickly.

Alternatively, the coil can be moved to a structural location such as an inner fender or frame brace to isolate it from the engine a bit.

Just a heads-up,

Tom

PS: Way back I had a similar problem. It turned out to be a bad butt splice connector in a wire going to the coil. At first it was intermittent, later had to trailer the car home. Took some real detective work to find it as it was located under a fender in an enclosed space. The clue was no voltage at the coil. Maybe you could connect a voltmeter to the hot side of the coil and wiggle wires here and there while watching (or your assistant watches) the voltage.

[patrickt]

About ten years ago I had a similar intermittent electrical problem. I was able to pinpoint it by having temporary 12v lights wired to the critical circuit points so that when the problem occurred I could just look to see what light was out and that tipped me off to where the problem was. Try wiring a light to the On/Off 12v+ feed to the MSD box right at the box itself. Take her for a run and, when she cuts out, tell us if the light is still on. Likewise, have a second light wired to the always-present 12v+ and 12v- feeds to the box. Since that light will always be on, what I did was just hook it up with alligator clips before a run. If it is indeed an electrical issue, this is a pretty good way of identifying it. It won't spot everything (like a flaky coil), but it will eliminate a lot of possibilities. I do like the MSD Hi-Vibration coil, and that's what I have. But don't start replacing things until you've exhausted the light bulbs trick. The problem with an intermittent fault is that you can accidentally "jiggle" a bad connection somewhere in to working right and you think you've fixed it, but you really haven't.