testing amp igniton box

Hello all,

What is a for sure way to test to see if the amp box is dyeing?

I have a 1972 Johnson 85hp with breakpoints and one coil.

Just want to make sure im going after the right part.

Thanks in advance.

Re: testing amp igniton box

So does it have spark? If it does, it is working. If no spark, you need to do some troubleshooting to isolate the trouble. Disconnect teh blue coil wire from the terminal strip, unbolt the coil, and turn the whole thing to unscrew the spark wire from the distributor cap. Remount the coil and reconnect the blue wire. Rig up a spark gap off the end of the spark wire. Crank the engine with the starter, watching for sparks at the spark gap. Sparks = everything is working up to that point.

If no sparks, connect a voltmeter to the purple wires at the terminal strip. Crank with starter and observe voltage. Should be at least around 11 volts. If not, find out why the low voltage. Voltage OK, disconnect the black/white wire between the amplifier and distributor cap. Turn key on and brush / touch the black/white wire coming from the amplifier to a good ground, observing for sparks at the spark wire gap. Sparks = everything is OK up to that point, and time to pull the flywheel and see what's wrong with the points or distributor. But if no sparks, either the amplifier or coil is bad. Your guess without more sophisticated test equipment.

Re: testing amp igniton box

So it has spark right now. The other day it didn't. When I was trouble shooting the ignition. Following what was in the manual for tsing. Then is started to work. Didn't change anything.

Re: testing amp igniton box

That does make it tougher. You almost have to catch it when it isn't working. However, it probably is not the amplifier. More likely a voltage input problem at the purple wires or breaker points problem. Also, those things have a crummy distributor.

Make darn sure your battery cable connections are shiny bright clean and tight. Those can kill the amp.

Re: testing amp igniton box

Sometime she runs like a champ and other times not so well. I have killed the battery, due to a short in the key switch. Ever since then, not running so well.