View Full Version : coil questions

08-11-2014, 09:53 AM
having an issue with restarting when hot this just started last weekend when a coil gets hot and fails does it fail or if it cools off will it work again.

it started with the motor running a tad warmer nlast weekend I went in to fill up and it was hard starting turned over but no sounds of spark started on the 3rd or 4th try. yesterday after running around for an hr or so I stopped by a friend to talk turned her off and wouldn't restart something smoked( blue) in the carb the electric choke fried ? when I got to the dock I touched the coil it was hot

the coil has an internal resistor



08-11-2014, 02:38 PM
Coils can definitely fail when they get hot and work again after cooling off. That's a pretty common symptom before they crap out entirely. If yours gets + power from the choke (as they are sometimes wired) that might explain the discoloration on your carb.

There's a bench test you can do on the coil to check internal resistance. The specific ohm specs are in the service manual if it's stock, and online if it's an aftermarket coil. That and checking to see how it is wired (and the condition of the wiring) would be a good starting point. Coils are cheap enough that it would be worth checking the wiring, replacing the coil, and seeing what happens. Worst case you end up with a spare.

08-17-2014, 08:44 AM

looks like I had a mismatch with my coil

the issue of an internal or external resistor is one thing but the other thing is making sure the coils primary resistance matches your dist components.

my mallory unilite electronic dist needed 1.4 ohms primary resistance the coil I had was .07 ohms

I spoke to a tech at Mallory and he said in my application it would be better to run an external resistor with the Mallory coil and Mallory unilte dist. basically the dist and breaker will run on all of the juice the coil will put out on 12 volts but is more reliable with the resistor running at 9 volts a track versus street thing.

so new coil and ballast installed