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1992 Johnson 120 hp sputtering at WOT help!

C

Chuongnino

New member
Hello and thanks again for your help in advance. My 1992 Johnson V4 120 hp is giving me a challenge again. I started it today before an outing and as soon as I pass 3/4th of the throttle it would shake and sputter. When I reduce the throttle it would go back to normal and stop sputtering. I attached a video link below for your reference.

checked all connection and sparks are clean and tight. I tried pumping the bulb when it sputters but that did not help.

Could you please point me to the right direction where should I check next?

<a data-cke-saved-href="https://streamable.com/5bikb1" href="https://streamable.com/5bikb1">[video]https://streamable.com/5bikb1[/video]
 
Sounds like an ignition miss. Put a timing light on each cylinder and look into it for black spots. That's the cylinder with the ignition miss.
 
How about you stop revving it in neutral!!!! A misfire will happen if you rev it on muffs. That is also a good way to wreck your motor. What does it do on the lake. How many forums are you going to post this problem on before you answer that question???
 
What do you mean by revving in neutral? I had it in gear in the video. It did awesome on the lake previously, have not had the time to go out on the lake to test yet. Before going out on the lake I usually start it up to check if battery and fuel.... are all working. I know running on a muff is not really recommended but that the only way to check. I had to paddle numerous times before (and don’t like it) and this is an old motor so I’d like to check it before going out.

Not trying to be disrespectful but did do anything wrong by posting my question in several forums? That bothers you?
 
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Boobie said:
Sounds like an ignition miss. Put a timing light on each cylinder and look into it for black spots. That's the cylinder with the ignition miss.
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thank you very much that’s a possibility. I had a no spark issue before this happens so I replaced the power pack and ignition switch. All sparks are jumping good 7/16th gap now. I would have to do some more research on how to perform that timing light test accurate. Thanks again!
 
???----Sure your motor was in gear on the trailer !!!!-----But the propeller was not doing any WORK.-----So really that is still neutral , you need to understand and agree with that concept.------No water in the exhaust housing to cause back pressure either.-----Test this thing in the lake !!!
 
racerone said:
???----Sure your motor was in gear on the trailer !!!!-----But the propeller was not doing any WORK.-----So really that is still neutral , you need to understand and agree with that concept.------No water in the exhaust housing to cause back pressure either.-----Test this thing in the lake !!!
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Yes I understand it now and thank you, my understanding of neutral is different. I have no knowledge of these engines so youtube and google search are mostly what I got. You don’t know what you don’t know. I am willing to learn but I swear there are folks really ....... trying to give people hard times for nothing.
 
Chuongnino said:
You know what, I sure will need luck. But I don’t appreciate your manner so please have your luck back. Bless your heart!
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Is it my fault you cannot answer the most basic question?? Your motor is not going into slow mode. But hey you keep looking for things wrong. I look forward to your next post wondering why there is a hole in your block. Just keep abusing your motor that way you will be here a lot. My advice to you is sell your boat before you destroy it. God bless and protect you from the shrapnel that will eventually come out.of that motor.
 
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flyingscott said:
Is it my fault you cannot answer the most basic question?? Your motor is not going into slow mode. But hey you keep looking for things wrong. I look forward to your next post wondering why there is a hole in your block. Just keep abusing your motor that way you will be here a lot. My advice to you is sell your boat before you destroy it. God bless and protect you from the shrapnel that will eventually come out.of that motor.
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It is no one’s fault. I have little knowledge of the matter that’s why I come on here and ask. Something might be basic to you but not to others. When I don’t understand a certain thing I also ask. I know I am asking for free knowledge so I ask questions in a respectful manner as well. If you are here to help, people appreciate that. So do I. But if you don’t feel like helping or explaining, please ignore. You don’t have to be sour like that!

Imagine bringing your children/grandchildren to a class or activity they have not been to much. I’m sure you don’t like it when they keep coming home saying others in the class give them %**^** about not knowing enough basics.
 
Rwbutler said:
And what makes you think it's not going into SLOW?
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Because I can make my 15 hp misfire like that on muffs by revving it to high. Usually full timing advance is at around 3500 in gear on the water. When you rev it on muffs like that you can get to 3500 rpm without even being close to full advance. So your motor is essentially out of sync\time thats why you get that misfire bounce. Another reason is because on muffs you cause a lean condition by revving it like that. I also did not hear an alarm for overheating, and he ran that motor a long time like that to not have overheat damage. If you dont believe me easy enough to prove next time you have a small motor try it. I told him to take it to the lake and run it as muffs are not a real test of anything. This OP wants people to tell him what he wants to hear. Sell your boat as i do not see it running very long for you or find a dealer to service your boat.. It is not a crime not knowing something but I told you the same thing twice. You got free advice and your to lazy to actually take it. I am sure soon enough you will know a lot about that motor when it explodes.
 
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I did not say it was overheating.I did not say I heard a warning horn. If you listen you can hear it go in and out of slow. I hope someday you get a motor as big as your attitude.
 
Rwbutler said:
I did not say it was overheating.I did not say I heard a warning horn. If you listen you can hear it go in and out of slow. I hope someday you get a motor as big as your attitude.
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You asked why I dont think its going into slow I told you! I am also sorry that you consider revving a motor up on muffs is a Valid test of anything. If you want to.prove me wrong make a video of a motor revving up on muffs and running perfectly. I gave him a great piece of advice go to a dealer some people need them. How many motors have you run on muffs like that??? And had good results???


P.S If read his post it ran great on the lake and not in his backyard hmmmmm.
If you want people to kiss your ass pay them. Dont look for free handout then complain about it.
 
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Rwbutler said:
And what makes you think it's not going into SLOW?
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One more thing why I dont think its going into slow. The title of the says it does it at WOT and slow.happens around 3000 rpm. He could just as easily be hitting the rev limiter. Very easily proven by putting it in the lake!!!!!!!!!!!!!!! I am not a professional muff runner i will leave that to you!!!!
 
Chuongnino said:
thank you! I suspect that too was an issue. Water not spitting right so I am replacing the water pump as well.
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Check eng. Temperature at top of both heads, should be around 143* at idle.Check eng. Temp while problem exist and post. Does the boat have a tachometer? Test your warning horn.
 
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