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92 25 hp outboard sputters

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hampster63

New member
Hi all,
I've got a 1992 Johnson 25 hp. the motor runs fine on start up. After it warms up and I back off the throttle the Idle and low speed is fine. Once I get to about 1/4 throttle or more the motor will surge and sputter. I've rebuilt the carb. Replaced the fuel pump, new plugs and set the gap. Any suggestions?

Dave
 
3 things to do.-------Try opening the LOW SPEED mixture screw 1/4 turn.----Check that throttle plate opens at the correct time.------Check the stopper on that throttle rod that goes to the back on the port side.----Is there about a 3/16" gap at idle , yes or no ?
 
Had a similar situation and I was getting air into the fuel pump from a leaky fitting prior to the pump... It's vacuum was pulling in a little bit of air and after a bit there's enough air that it started doing the same thing... And you don't ever want to get lean condition...
 
Tattoomike, I replaced all the fuel and vacuum lines when I did the pump, this was a real basket case when it got to me, but I'll recheck all my lines and let you know.
 
I switched to see through fuel lines for exactly this reason...
Hope you get it figure out easy enough tho...! Suck to have issues when you could be having fun
 
Have you checked the fuel supply line and tank? Is it a plastic tank, has it been exposed to ethanol? Some plastic tanks will allow air entry at the connection inside the tank where the top of the suction tube attaches to the fixture. Ethanol will shrink this tube and sometimes to the point where it will even fall completely out.
 
timguy said:
Have you checked the fuel supply line and tank? Is it a plastic tank, has it been exposed to ethanol? Some plastic tanks will allow air entry at the connection inside the tank where the top of the suction tube attaches to the fixture. Ethanol will shrink this tube and sometimes to the point where it will even fall completely out.
Click to expand...

Exactly..... That could cause air to get pulled in the fuel system as well....
 
No I have not checked the tank and pickup line. It is a plastic tank and the carb had a very bad case of ethanol crystals in it. I'll be check that as well this afternoon. I did notice that the pump ball always seemed to never get hard so maybe it is sucking air from the that line. FYI I did put a new ball on it too.Thank you.
 
So far everything has check out, I did find what looked like fuel varnish or part of a bug in the quick connect at the fuel tank, also found a swollen o ring on the pick up tube cleaned and replaced all. she ran fine for awhile and start the same thing over again. I'm going to pull the carb and break it down again, maybe some crap made it up to the carb, also going to install a inline filter on the fuel line. I'll keep you posted.
 
Hi.I am new to outboard and trying to double my way around in here looking for why my 92 9.9 stumbles and won't get wot. Kinda sounds like some of my problem here. So I'm trying to relate everybody's input to try to gain me some knowledge.In my younger days of racing mx i watched and listened and learned.
 
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