Help with testing Coils....

[leenolan82]

Hi Guys!!

Im hoping someone here may be able to shed some light on how to properly test a coil.....

I have a 60 HP johnson 2 cyl (J60TLCIH) that i suspect has a coil breaking down under load.. IM not exactly sure how to test it properly and isolate the fault. I dont want to go and buy new coils if i dont have too.

I have just rebuilt this motor so it has great comp both cyl's, new carbs, timing is spot on, everything seems to be operating as it should.

when i start the motor on the mufs its fine. when i put it in the water it starts and idles ok, picks up to about 2000RPM and then just bogs down. feels like the timing is retarted, but its not. Im thinking maybe a coil may be breaking down.. they both look very old and sad..

so if someone could shed some light on how to test these it would be a huge help...

thanks guys!!

 

[nwcove]

Re: Help with testing Coils....

there is a good vid on yutube, doug penn testing old outboard coils, but it may not help completely with your issue. still worth watching tho.

 

[Cofe]

Re: Help with testing Coils....

Another test is to place a jumper wire on the metal part of the coil, and ground it to a clean ground on the motor. Sometimes the ground strap on the coils.....usually the lower bolt hole ground strap on the back side of the coil, is on a painted or corroded surface on the coil mount. This can cause a coil to not work, or cut in and out as the motor heats up.

 

[tx1961whaler]

Re: Help with testing Coils....

If the coils look old and sad, then by all means replace them before they let you down in the middle of the lake and ruin your day.
http://www.iboats.com/mall/partfind...d_poid=334772&gd_row=176&**********=922196283
http://www.iboats.com/mall/partfind...d_poid=109170&gd_row=176&**********=922196283

 

[leenolan82]

Re: Help with testing Coils....

Does anyone have to correct resistance readings these coils should be?

 

[BonairII]

Re: Help with testing Coils....

Does anyone have to correct resistance readings these coils should be?

Your ignoring the obvious answer....just replace the coils!

In many cases, being cheap ends up being very expensive in the end.

You're only have to end up stranded once, and you'll wish you had replaced 'em.

 

[Haffiman]

Re: Help with testing Coils....

It does not help doing a static ohm test of a non running coil if it is 'breaking down' only under load.
Hook up a timing light and check while running.
Another way is to 'heat' up the coil with a hairdryer, hook up a spark tester and crank. If spark is disappearing or getting reduced when 'hot', change!!