2000 Johnson 90 hp problem

D

Dave Bureau

Recruit
Joined
Oct 9, 2004
Messages
1
I have a Johnson 90hp outboard that keeps droping back to 3000 rpm from full throttle. This is not a fuel problem. I have an inline filter and water separator. I have replaced the water pump, flushed the cooling jackets, replace the plugs, and replaced a cracked temperature sensor. I know that the engine will drop back to 3000 rpm if there is a cooling problem in the cylinders. I have taken the motor to a Johnson authorized service center, and they can not seem to find what is wrong. I think it is a defective heat sensor or a clogged water jacket since it is confined to the left cylinder bank. Any thoughts or ideas on what I should do next would be greatly appreciated.
 
clanton

clanton

Rear Admiral
Joined
Jul 9, 2001
Messages
4,876
Re: 2000 Johnson 90 hp problem

If a 60 degree engine, check power pack, sensor, ignition coils, engine running, loaded.
 
S

seahorse5

Rear Admiral
Joined
Jan 24, 2002
Messages
4,698
Re: 2000 Johnson 90 hp problem

If the motor is overheating, the alarm and indicator lites should warn you, as long as the system is operational. Has it been checked?<br /><br />A flakey power pack or even the wrong sparkplugs can trigger the motor to go into SLOW without setting off the horn. Make sure to only use Champion QL78YC plugs gapped at .030"
 
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