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1993 40 hp Classic 4cyl ignition issues.

C

Cassville

New member
Hello all, I am new here and hope someone can help me out. My 40 horse is putting out a very nice blue spark on cyls# 3 and 4, and a very weak to non existent spark on cyls #1 and 2. I replaced the stator with a good (tested) unit, and had the same results. I then moved the coil from the # 4 cyl to the # 1 cyl and found the same result again. I'm not too familiar with the ignition system here but I think my trouble must be "up stream" of the coils somewhere. ( I should mention here that I had replaced my plug wires last year before this weak spark issue started.) Any ideas? Thanks. Cassville.
 
Sounds like a bad trigger coil. It's under the flywheel. You can test it with a meter for conductivity.

Jeff
 
Bad switchbox as trigger has nothing to do with output to coil other than to tell it when to fire plus pairing is off for trigger....
 
faztbullet said:
Bad switchbox as trigger has nothing to do with output to coil other than to tell it when to fire plus pairing is off for trigger....
Click to expand...

Thanks for the speedy reply..... Is there a way I can test the switch box? Could I move the red, red/white, blue, blue/white wires around and "chase" the weak spark to other cylinders? If it does prove to be the switch box, Would it be foolish to try and buy one on the surplus/ebay market, or just bite the expensive bullet and buy new? ( I think I know the answer already but will wait for your kind reply);) thanks, again. Cassville.
 
I went a head and did the red, red/white wire swap...same result. Then I finally figured out that maybe I should be swapping the green wire side of the switch box. Swapped the #1 cyl green wire with the #4 cyl green wire and found a hot spark on #1 and a weak spark on # 4. So I do believe the Switch box to be the culprit. Does any body out there have a good used switch box they would like to sell on the cheap? Thanks. Cassville.
 
..."Bad switchbox as trigger has nothing to do with output to coil other than to tell it when to fire plus pairing is off for trigger"

And if one of the circuits is open.... Test it with a meter before spending money on switch boxes (that can not be tested with a meter).

Jeff
 
And if one of the circuits is open..
Click to expand...
Nope.... If for example #1 trigger lead was open # 3 would not fire due to they are a pair as one end becomes SCR ground due to magnet polarity..Still they have no voltage or function to coil output as they only fire capacitor. Most likely bad diode or resister. Below is layout of box and only good for minor tests as cannot test internal rectifier or capactior

Scan.jpg
 
Put a new switch box in this evening..... now have a very hot spark on all four cylinders. Will be lake testing the motor this next Sat.
 
The 40 hp started and ran very well....for about 20 minuets! Everything was fine and then it just flat out quit. I limped back to the dock on the trolling motor and thought about it on the way home.. It was acting as though the kill switch had had been activated. I took the cover off and found the yellow/black kill switch wire on the new switch box was pinched down against the non insulated side of the switch box. I re-positioned the yellow/black lead and put it all back together and everything seems to be good again.
 
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