48 hp Johnson

Bigtom27

Recruit
Joined
Aug 23, 2011
Messages
1
I have a 48 hp Johnson '88 model that will not idle. I have cleaned fuel tanks, lines and carbs 3 times. It tries to idle but just does'nt make it. What do I do next?
 

Monte1961

Lieutenant Junior Grade
Joined
May 8, 2011
Messages
1,180
Re: 48 hp Johnson

When you say cleaned carbs 3 times, just what do you mean by that? 1st. were carb/s taken compleatly apart? 2nd. were the core/welch plugs removed? 3rd. did you soak carb/s in carb cleaner for 24 hrs? 4th. were new carb kit/s installed? 5th. did you scrub all parts with a scrub brush? 6th. did you rinse throughly with fresh water? 7th. did you you use compressed air to blowdry and make sure all oriffices were clear? If not, you might wanna go back and do it again! Just sayin! Post back your results.
 

cjr1971

Cadet
Joined
Sep 17, 2009
Messages
27
Re: 48 hp Johnson

Sorry for butting in monte. but could it be as simple as turning the idle adjustment ?
 

rawhide44

Recruit
Joined
Aug 25, 2011
Messages
1
Re: 48 hp Johnson

It has all been cleaned carb working>the engin startsw and as long as working throttle it will run misses but runs will not idel and will die as soon as let off throttle.compresson good I am leanning to the points please help
 

bob johnson

Rear Admiral
Joined
Feb 25, 2009
Messages
4,304
Re: 48 hp Johnson

I have the same motor, it doesnt have points!!

you might need to do a lync and sync.

its a methodical resetting of the throttle position and the timing....

plus it might be a combo of a dirty carb AND the timing off!!

cleaning a carb might be a misnomer.

you really need to REBUILD the carbs sometimes...new gaskets, new needle and seat, new float, pull the core welch plugs and thoroughly clean all debris from all the passages and methodically ressaemble, setting all adjustments to the book!!

I had been told my an old mechanic that those 48-50 hps didnt idle well at all..especially out of water.....

but it shouldnt die...mine will run for ever on the muffs, but it doesnt sound smooth!!

"cleaning a carb" is a very slippery term used in all kinds of ways to mean different things.....

personally id start with a compression check to verify good compression in both cylinders. then Id do a spark check to know that both plugs have juice to them and that the juice is good and strong!!!,

THEN id do all the other stuff

good luck

bob
 

194269

Petty Officer 2nd Class
Joined
Jul 9, 2011
Messages
104
Re: 48 hp Johnson

When I was working part time at a dealer, a customer came in with a 50 HP saying it would not idle. Do you think that #1 having ZERO compression had anything to do with it ????????? :D I have a 40 HP on my pontoon boat and is not a smooth idling engine but it stays running @ 900 in neutral and 750-800 in gear.
 

Borgey401

Petty Officer 2nd Class
Joined
Jun 11, 2011
Messages
155
Re: 48 hp Johnson

When I was working part time at a dealer, a customer came in with a 50 HP saying it would not idle. Do you think that #1 having ZERO compression had anything to do with it ????????? :D I have a 40 HP on my pontoon boat and is not a smooth idling engine but it stays running @ 900 in neutral and 750-800 in gear.

HAHA, maybeeeeeee?
 
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