Timing light trouble Johnson 90HP

Here’s an interesting question. While checking the timing on my 1989 V4 Johnson 90HP per the Joe Reeves cranking method I connected my timing light inductive pick-up to #1 lead with the arrow on the pick-up pointing towards the spark plug(tester 7/16”) as I normally do when checking the timing on automotive engines but it would only work occasionally or sometimes not all, upon turning the inductive pick-up around so the arrow was now facing the coil it worked fine. Do you think the polarity of the spark is different or the voltage with copper conductor leads to high for the pick-up? Anything to worry about.<br />By the way I tried it on my car and it work fines either way.

Re: Timing light trouble Johnson 90HP

Different models of Johnson-Evinrude outboards use opposite polarity ignition systems. On motors that use electronic controls in the power pack and/or timer base (QuikStart, S.L.O.W.), normally use opposite polarity and you have to orient your timing lite pickup with the arrow facing AWAY from the sparkplug.

Re: Timing light trouble Johnson 90HP

sometimes it makes a difference. my ferret instruments timing light wont work in the dark or in a dark engine box. I dont know why it just wont. I sometimes have to face the sparkplug side away from the plug as well. also be careful that it does not pick up stray voltage signals and give a double flash.<br /> good luck and keep posting

Re: Timing light trouble Johnson 90HP

I’m pleased there’s nothing wrong with my timing light or engine ignition, as long as the arrow on the inductive pick-up is pointing away from the plug it all works fine on my model of timing light.<br /><br />By the way WOT timing was at 20 deg BTDC so I set it to 24 deg BTDC (cranking method) actual running full advance should be 28 deg and will check it at the boat ramp in a couple of weeks. Hopefully might help my fuel consumption a little. <br /><br />I keep a close eye on this site for tips and info and really appreciate the effort and knowledge that goes into the replies. Thanks!!!

Re: Timing light trouble Johnson 90HP

Be sure to check it under a load at or near your top rpm's. We use this method as a starting point only.

Re: Timing light trouble Johnson 90HP

In order to check it under a load at WOT, I suppose you have to be cruising along in relatively calm water and then remove cover and attach timing light and check, adjust spark advance screw?

Re: Timing light trouble Johnson 90HP

Originally posted by 87Aggie:<br /> In order to check it under a load at WOT, I suppose you have to be cruising along in relatively calm water and then remove cover and attach timing light and check, adjust spark advance screw?

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I couldn't get the JR method to work and wasn't smart enough to mess atound with the inductive pickup direction. Your idea is close to what I ended up doing with a pontoon boat.<br />This is a 15 to 20 mph boat so many of you will want to pass on hanging out the back at 50 to 70 mph. From my chest up was all I had to have beyond the rear lounge seat so I felt pretty comfortable doing it.<br />I removed the cover, connected the light, had my wife drive while I checked the timing. You only need a couple of seconds to check it. (Just about long enough to fall overboard) If it needs adjustment, stop, make the change and recheck it.<br />It actually was quite easy.

Re: Timing light trouble Johnson 90HP

My Jet Boat is a 45 mph boat, and I sure as heck don't want to be moving when I check the WOT timing.<br /><br />I used two stout lines to two stout trees, tied off to the stearn rings. I checked the timing as quickly as possible, and still dug a pretty good hole in the sandy bottom about ten feet behind the boat.<br /><br />fp