1988 90hp johnson bogging down

thiker15

thiker15

Petty Officer 2nd Class
Joined
Jan 1, 2008
Messages
103
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Hi all, my 1988 90 hp starts great and up to half throttle runs super, anything passed that it boggs down. But when I choke it she runs like nothing is wrong. Can anyone help?
 
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emdsapmgr

Supreme Mariner
Joined
Dec 9, 2005
Messages
11,551
Re: 1988 90hp johnson bogging down

Sounds like it is running lean. When you choke it, the choke solenoid enriches the mixture and it takes off. When this happens, try constantly priming the bulb on the fuel hose. This will force extra fuel into the carbs. If it runs fine at top end while you are constantly priming that hose bulb, you may have a fuel restriction or a weak fuel pump. A weak pump won't supply adequate fuel to run full speed-you may even see the engine speed up, then reduce speed, then speed up again-all while the throttle is in the same position.
 
thiker15

thiker15

Petty Officer 2nd Class
Joined
Jan 1, 2008
Messages
103
Re: 1988 90hp johnson bogging down

Thanks for the reply. The first thing I tried was squeezing the primer bulb it stayed hard but did nothing to stop the bogging down, the only thing that helped was the choke.
 
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emdsapmgr

Supreme Mariner
Joined
Dec 9, 2005
Messages
11,551
Re: 1988 90hp johnson bogging down

In that case, the fuel pump may be ok. Always possible that you have a restriction/blockage in one of the high speed jets. When the carb butterfly opens, it gets more air, but no more fuel. That can be a dangerous situation. Too much air and not enough fuel is not good in a 2 stroke. You may need to pull the carbs apart for inspection and cleaning. Or you may be able to get an approximate idea what is going on by just pulling the bowl drains out and remove each of the 4 high speed jets-then visually inspect them.. That's a little tricky if you don't have some special tools.
 
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thiker15

thiker15

Petty Officer 2nd Class
Joined
Jan 1, 2008
Messages
103
Re: 1988 90hp johnson bogging down

Thanks, I'm bringing it to a mechanic tomorrow.
 
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