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-   -   1991 Johnson 3 HP problem (http://www.sailnet.com/forums/gear-maintenance/79064-1991-johnson-3-hp-problem.html)

RWeber 09-23-2011 08:56 PM

1991 Johnson 3 HP problem
 
Hello, I have searched in vain for a solution to a problem with the new to me, 1991 Johnson 3 HP outboard I bought recently.

For the last four outings it ran great, now it seems to only speed up until half throttle then stays there no matter how high I push the throttle, it doesnt speed up.

it will spit and kick into higher speed for an instant but then back to slow speed.

I thought it was fouled plugs but can not so far get teh bolt out of the center of the cover to get at the plugs, its pretty buggered upa nd rusty and it so far will not budge, I have marvels oil on it now hoping it seeps in and loosens it up.

two people with me were of the opinion that the half speed was caused by 1 cylinder firing, but in neutral I can revv it up much too high if I wish too, but under load its not performing as it was originally.

any ideas?

thanks and great forum.
Bob

Faster 09-23-2011 09:07 PM

Could be a plugged fuel filter, or perhaps a clogged jet/passage in the carburetor. Also it's unlikely that this is a 2 cyl engine at only 3 hp. If it's spitting and gives a kind of 'wheeze' when it dies I'd look into cleaning and rebuilding the carb.

jgeissinger 09-24-2011 12:44 AM

Johnson 3
 
The 3hp Johnson 2 stroke is a twin cylinder motor. Figure out a way to get the cover off, drill the bolt out if you have to, and put new plugs in it. Then put fresh gas with 50 to 1 oil mix and try it. All those need is fuel and spark and they will run forever. Try everything else before tackling a carb rebuild.

Faster 09-24-2011 01:22 AM

Quote:

Originally Posted by jgeissinger (Post 778980)
The 3hp Johnson 2 stroke is a twin cylinder motor. ..

Well... who'd a thunk it!?! That's a small twin. Thanks...and sorry for the assumption.

RichH 09-24-2011 10:53 AM

Small Johnson & Evinrude OBs easily blow head gaskets if the head is not routinely re-torqued ... check compression, after cleaning the carburetor. The good news is that parts are still readily available online from a quite large distributor network. websearch: Johnson + outboard + parts.

RWeber 09-26-2011 01:56 PM

Quote:

Originally Posted by jgeissinger (Post 778980)
The 3hp Johnson 2 stroke is a twin cylinder motor. Figure out a way to get the cover off, drill the bolt out if you have to, and put new plugs in it. Then put fresh gas with 50 to 1 oil mix and try it. All those need is fuel and spark and they will run forever. Try everything else before tackling a carb rebuild.

thats the ticket thanks, worked well, but got myself into a jam with putting a new waterpump in, having trouble lining up shift rod and copper waterline while getting the driveshaft engaged too.

there a trick to it?

turn the motor upside down or something?

what a pain keeping all three in line and getting that copper back intot he boot on the waterpump.

sorry I tackled this impeller replacement, that was a cinch but what a pain getting this lined back up!

thanks for any first hand knowledgeable help.

dabnis 09-26-2011 03:46 PM

Not familiar with your motor but have changed impellers on 6HP and larger Evinrudes. On those motors there is a small access plate on the lower unit where you disconnect the shift rod which stays connected to the upper part of the motor. Not sure if the 3HP has that plate? The copper water tube is tricky to get back into the block. On mine there was an "o" ring in the block that kept falling out. I finally put some gasket sealer on it to keep it in place. Turning the motor upside down might help, at least you can see better. The driveshaft should go in once you turn it a little each way to line up the splines. The water tube was the most difficult part. Maybe an extra set of hands might help?

Dabnis


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