90hp johnson rmp drop

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rlopez40

Recruit
Joined
Jun 9, 2009
Messages
2
By boat takes off like a bat out of hell but will bog down then take off again it will do it off and on sometimes it runs fine for awhile and at time it will do that all day. Just had everything checked on it after it was sitting in storage ran great for a few days been through two 35 gal tanks, cleaned the fuel pump last night had a little trash but not much.
 
C

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
28,803
Re: 90hp johnson rmp drop

you might check the antisiphon valve in the fuel tank pickup fitting. They get stuck and can have trash in them. When it dies, does pumping the primer bulb help? If so, the fuel pump may need a rebuild or the filter needs cleaning. For more specific help post the year of the motor.
 
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emdsapmgr

Supreme Mariner
Joined
Dec 9, 2005
Messages
11,551
Re: 90hp johnson rmp drop

You may have a weak fuel pump. The engine may be consuming fuel faster than the pump can get it into the carb bowls. It will cause the running problems you describe.
 
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rlopez40

Recruit
Joined
Jun 9, 2009
Messages
2
Re: 90hp johnson rmp drop

not sure on the year if i had to guess i would say 1990 to 1999. the fuel pump is brand new but the boat never cuts off. it goes from 7000rpm to 3000rpm and will keep on running. and i tried primimg the bulb but no luck i will check the antisiphon valve. i took apart the fuel pump it looks good, and i have a built in tank on a 1998 larson 186 sei if that helps

thanks for the help
 
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emdsapmgr

Supreme Mariner
Joined
Dec 9, 2005
Messages
11,551
Re: 90hp johnson rmp drop

You could have a problem with the fuel pickup in the tank. Temporarily try a 6 gallon tank and see if there is any difference.
 
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