1996 johnson 48spl

saltydog1

Seaman Apprentice
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Oct 4, 2014
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30
Went to the river Monday ran about a total of 6 miles, motor ran great didn't miss a beat. Went back Saturday afternoon back down ramp motor would not start. No spark to either cylinder, thought maybe kill switch is at fault, disconnected the black/yellow stripe wire. Still no spark, came home checked wiring and a few other things everything seemed to be ok thought ok power pack is bad. Until I found where someone said the rectifier could cause it to loose spark, so I disconnected the 3 yellow wires and one grey wire, guess what she fired up. So I hooked all wiring back up the way it was and guess what she still fired up. So know I'm puzzled!! Can anyone explain why this happened and should I change the rectifier. I did not check to see if it was putting out proper voltage.
 

boobie

Supreme Mariner
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Nov 5, 2009
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20,826
The rectifier (battery charging system) has nothing to do with the ignition system. You may have a power pack going bad.
 

saltydog1

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Oct 4, 2014
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That's what I thought to should not have anything to do with ignition. But it's very strange I don't understand why it started up after disconnecting the three yellow wires and one little grey wire
 

boobie

Supreme Mariner
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Power packs can act strange when going bad. Take it out and run it again.
 

saltydog1

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Oct 4, 2014
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Thanks for the reply and advice gm280, I will clean and check. But just got on and seen your message, and just got back from river, motor ran like a top but did miss fire 3 times on me at Wide open throttle like it was going to die and then came right back. Any ideas on why that may have happened it's never done this before.
 

saltydog1

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well it defanately will not hurt anything that's for sure. I will take time and do that. But like you said they all look great the motor looks brand new under hood it's always been freshwater run.
 

saltydog1

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Oct 4, 2014
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Ok guys so I did a little more investigating after cleaning all connection. Here is what I came up with I pulled spark plug wire off the bottom cylinder and did not make any difference in run of motor pulled top plug wire and motor shut down, so I did a spark gap test and both jumped a 7/16" gap but not a shark blue spark looked more redish to me. Should it have made a difference in run of motor when I pulled bottom plug wire?
 

boobie

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Was there any spark coming out of the bottom wire when you pulled it off ??
 

saltydog1

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Oct 4, 2014
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I took the top plug wire of the coil and put it on the bottom plug and it ran but had to hol throttle open for it to stay running swapped plugs and it still done same
 

boobie

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If you did that it should have been out of time and not run at all.
 

saltydog1

Seaman Apprentice
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Oct 4, 2014
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You are right boobie it did not run or even try to crank I said that wrong.
So motor runnning pulled top plug wire shut it down
Motor running pulled bottom did not affect it. Checked spark with gap tester and spark looked the same and jumped the same gap.
Pulled the top wire and tried to crank with just bottom wire had to open throttle for it to run
But it will crank ok and idle with just top plug wire hooked up
Spark gap test the same top and bottom cylinder 7/16" gap with same color spark
do you think I could have just a dirty carb
 

Vic.S

Rear Admiral
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May 4, 2004
Messages
4,690
You are right boobie it did not run or even try to crank I said that wrong.
So motor runnning pulled top plug wire shut it down
Motor running pulled bottom did not affect it. Checked spark with gap tester and spark looked the same and jumped the same gap.
Pulled the top wire and tried to crank with just bottom wire had to open throttle for it to run
But it will crank ok and idle with just top plug wire hooked up
Spark gap test the same top and bottom cylinder 7/16" gap with same color spark
do you think I could have just a dirty carb
You seem to have proved that it is not running on the bottom cylinder although running Ok on the top one

You now seem to have two equally good sparks. It is worrying though that at first you said you had no sparks on either cylinder and have cured that without really knowing why.
The fact that you have two good sparks indicates that the power pack and the coil assembly is OK. BUT there might be an intermittent fault that will return at some stage.

I think you have indicated that you have tried swapping the plugs over without it making any difference. If you have not try that and verify that it is still the bottom cylinder that is not working.

You seem to be suggesting in in post #16 that it will run with just the bottom plug hooked up if the throttle is opened .


A compression test would be the next logical step. Readings on the two cylinders should be within 10% of each other.

Also take a look around the carbs. Make sure both throttles plates open together. and that both are getting fuel.

If compressions are Ok,, you have 2 good sparks and nothing obviously wrong with the carbs externally then all thats left is to consider that the carbs, the bottom one anyway, may need cleaning
 

boobie

Supreme Mariner
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Try squirting some fuel in the bottom carb throat once and see what happens.
 

saltydog1

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Oct 4, 2014
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Thanks guys for input and suggestions. Will update as soon I get to check it out.
 
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