1991 60hp Johnson Missing at full power

J

jefflundstrom

Cadet
Joined
Jul 29, 2012
Messages
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Wondering if anyone would know what is the best thing to look at when the motor is really shaking (I think missing) at high throttle. I recorded it running, Chugging - YouTube Any help would be greatly appreciated.

Thanks,

Jeff
 
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WernerF

Petty Officer 1st Class
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Sep 5, 2011
Messages
320
Re: 1991 60hp Johnson Missing at full power

Looks like your motor is rev limiting at 3500 rpm. Does it run fine below? The video doesn't really show.

My first guess is power pack.
 
J

jefflundstrom

Cadet
Joined
Jul 29, 2012
Messages
11
Re: 1991 60hp Johnson Missing at full power

WernerF said:
Looks like your motor is rev limiting at 3500 rpm. Does it run fine below? The video doesn't really show.

My first guess is power pack.
Click to expand...

Yes, it does run fine at lower RPM. I tried to show that in the video as I asked the boat driver to go full throttle, then back down a little, go full throttle and then back down again.

Is there an easy way to test the power packs? I just had this motor rebuilt last year. I know the power packs were replaced 2 years ago.

Thanks,

Jeff
 
J

jefflundstrom

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Joined
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Messages
11
Re: 1991 60hp Johnson Missing at full power

So replacing the power pack did not help. Still misses but now at 4100 instead of right at 4000. We changed the prop, blew out the carb intakes and disconnected the rectifier as well. Have not done anything with the stator as of yet. What is really strange is this boat ran fine last year, and this year it is having problems, nothing has changed. Really frustrating. I think our next step is to rebuild the carbs as our only thought is maybe there is some junk in there from sitting. Does anyone have any suggestions as to what else we should be checking? Really appreciate any help or tips!
 
J

jefflundstrom

Cadet
Joined
Jul 29, 2012
Messages
11
Re: 1991 60hp Johnson Missing at full power

Rebuilt the carbs and still, same problem. Wonder if this could be an issue with the new fuel pump we put on. I am at a total loss with this one. Help please...
 
pn

pn

Petty Officer 1st Class
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Apr 20, 2013
Messages
374
Re: 1991 60hp Johnson Missing at full power

i always suspect the fuel pump, or fuel delivery. new is nice but doesn't always rule out defective, have you tried pumping the primer while motor is shaking, any improvement would suggest fuel delivery. on my carbs i let the carb body soak in carb cleaner for a night before blowing out all the passages, some people suggest running a small wire through the holes, you'd be concentrating on your main jet passageway. good luck. other things to check could be gasket on back of fuel pump or correct hose for pulsating tube, throttle position corresponding w/ remote lever position, wires shorting. float sticking...
 
J

jefflundstrom

Cadet
Joined
Jul 29, 2012
Messages
11
Re: 1991 60hp Johnson Missing at full power

Thanks so much PN for the reply. I will try the pumping of the bulb when it shakes. The bummer about all this is there is so many things it could be and we are getting tired of messing with it. The boat runs just a lot slower as we don't want to run it about 4K with this shake for fear something will break.
 
J

jefflundstrom

Cadet
Joined
Jul 29, 2012
Messages
11
Re: 1991 60hp Johnson Missing at full power

So finally after 2 months of aggravation on this I finally fixed it! Turns out the problem was that the spark plugs were gapped wrong. They were replaced by someone else at the start of the year so I never expected that was the problem. Finally out of desperation, I decided to try replacing them. Checked the gaps on the old ones and they were at .5!!!! They should be at .3. Changed the plugs and she runs like a dream!!!! Thanks again for all the advice here
 
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