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No Name Man
No Name Man
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Joined: Dec 2002
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MarcB Offline OP
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Originally Posted by gavin eisler
Next time it dies have a voltmeter handy, leave ign sw on, put red meter lead lead to batt positive, then follow batt neg, note reading , then black lead to ignition switch blue brown , note reading, then ign sw white , note reading. If these are all close to initial battery voltage with no significant drop then good, ignition switches are more unreliable than coils which are more unreliable than boyers in my experience. Ive never had to replace a Boyer, ive changed several coils and ignition switches.
A bad coil will often fail as it heats up, if you have some freeze spray , next time it fails spray the coils and see if it restarts.
All of this has been verified (other than the freeze spray) while the box was in "fail mode" in my garage. I took the coils out of the equation by checking voltage at the Boyer black wire and, when the coils aren't triggering, there's nothing there. One the box "wakes up", I get intermittent 12v as expected.

So now it's up to the black wire upstream of the connector, or either of the trigger wires upstream of their connectors (the ones closest to the box, not the trigger plate itself).

@John Healy: your article describes checking continuity at the trigger plate. Does the same apply to the w/b and w/y fires going into the Boyer box?

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Joined: Aug 2001
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Originally Posted by MarcB
Good news:
[*]Coils in series measure about 4.4 ohms on the primary windings (I'm guessing this translates to 2.2 per coil, but I haven't disconnected them from each other yet). Seems a bit high but I'm not sold on this being the issue yet.
[*]Coils measure 7k ohms on the output side[/list]


I did find that the red wire from coil to battery + was a bit frayed but replacing it with a test lead didn't change anything.

By the time I reconnected everything, I could not get it to restart. I actually see this as good progress because it will be easier to track down the issue if it's not so intermittent. I had to stop there but next steps will be to see if the plugs are firing (assuming it still won't start) and then whether I can get the plugs to fire by bypassing the trigger plate.

This suggests that you havent tested individual coil LT resistance,


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The poster formerly known as Pod
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MarcB Offline OP
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Well, I've replaced the Boyer (went with Vape instead) and so far so good. A Boyer replacement would have been around $90 to $100, and the entire Vape kit was $112 (for the Mk I model). I haven't done any real miles but have not had the motor cut out through multiple circuits around the block (usually managed no more than 1 1/2 turn around before the Boyer would cut out).

I'm still not certain that the issue was with the electronics in the Boyer itself but more likely one of the wires coming out of it. I could have rewired but, after 25 years, it had served us well. If the vape lasts as long I'll be 70 and it will likely be someone else's issue by then (maybe my daughter, though I doubt it)

I have to say the Vape install was clear-cut, especially matching the mark on the rotor to the stator plate. The Boyer's "paint dot" method was good for getting in the ballpark but the Vape timing was dead on first try. Maybe it's just a smaller ballpark wink

Lastly: I recently invested in a pair of ratcheting crimping pliers ($21 on Amazon). Holy crap, what the hell have I been doing all these years? Every connection is double-crimped nice and tight. They came in handy to fix the burnt headlight connector and replacing the EI. Anyone still using the auto parts store strip and crimp pliers should seriously look at getting a pair of these.

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