1972 25hp johnson idle and over rev issue

[Boat-ryder]

i just bought this motor and havin a few problems,first i had a hard time gettin it to idle in a test tank.the only way it would is if the needle valve was adjusted all the way out so that it wasnt even threadin in at all just sittin in there.i took it out for a test and it ran great,the next weekend i took it out and it wouldnt idle at all.it acted like it wasnt gettin fuel.then it started somethin new,every time i would crank it it would just started revving out of control right off the bat and i couldnt do anything to really stop it.and ideas? thanks

 

[Boat-ryder]

Re: 1972 25hp johnson idle and over rev issue

anybody?

 

[nwcove]

Re: 1972 25hp johnson idle and over rev issue

sounds like you need to clean and re-kit the carb.

 

[Boat-ryder]

Re: 1972 25hp johnson idle and over rev issue

i agree but could the carb have something to do with the over rev?cant let it do that too much or my motor will blow.

 

[AlTn]

Re: 1972 25hp johnson idle and over rev issue

sounds like your throttle is hung somewhere in its linkage...does your armature plate move when you twist the throttle grip or is it hung so it can't return to an idle position?...is the vertical shaft that links the twist grip movement to the armature plate moving?

 

[Boat-ryder]

Re: 1972 25hp johnson idle and over rev issue

when i twist the throttle grip it seems to move like it suppose to not sticking,im not where i can look at it right now but is there a diagram that will show the vertical shaft your talking about? thanks for the help

 

[AlTn]

Re: 1972 25hp johnson idle and over rev issue

marineengine.com...your year and hp...cylinder and crankcase...part#37...you'll see that it's connected to an arm at the top that moves the armature plate and this, inturn, opens the carb butterfly through a timing cam, roller, and carb linkage...the motor needs to be in gear for the armature plate to reach full movement

 

[nwcove]

Re: 1972 25hp johnson idle and over rev issue

if the butterfly in the carb isnt sticking open....plz check it, you could have had a " run a way" situation with the needle just laying in the hole.

 

[Boat-ryder]

Re: 1972 25hp johnson idle and over rev issue

Thanks for the diagram all the linkage is working fine, I pulled the carb today and it was clean not even in the bottom of bowl.kinda weird but I got it soaking anyway. Any chance vacuum could be the cause?