1995 Johnson "noses over" at full throttle

[boomer2]

J50TLEOD TWO cylinder slows down with the last tiny bit of throttle applied. Back off throttle a dab and it picks up speed slightly. Link and sync maybe? According to tach it only turns 33-3400 rpms, I realize tach could be off. Also engine runs cool..whatever lake water temp is what she pees. A good forceful return stream is coming out so I'll rule out the prostrate gland....

 

[fireman57]

Re: 1995 Johnson "noses over" at full throttle

Sounds like you might have dropped a cylinder. Get an old fashioned timing light and a buddy and check it while you are running. See if you have good spark on each cylinder with the throttle applied. Could be a weak coil.

 

[boomer2]

Re: 1995 Johnson "noses over" at full throttle

Just now finished a compression test. 150 on top hole and 148 on bottom. Don't really have anyone to drive me on the water while I check timing and spark under throttle but have a good long blue spark using spark tester. Its not a huge drop in speed at WOT..very small. But as stated I can back off throttle just a hair and engine picks up a fraction. Maybe I'm too picky, dunno.

 

[clemsonfor]

Re: 1995 Johnson "noses over" at full throttle

Just now finished a compression test. 150 on top hole and 148 on bottom. Don't really have anyone to drive me on the water while I check timing and spark under throttle but have a good long blue spark using spark tester. Its not a huge drop in speed at WOT..very small. But as stated I can back off throttle just a hair and engine picks up a fraction. Maybe I'm too picky, dunno.

Just a hunch, pull the cowl off and the cover thats over the carbs. Now watch the butterflys as they open up, are they parallel with the ground at WOT or cocked upward a tab?

Im thinking that they may be all the way open (papallel) slightly before WOT and when you push your throttle to WOT the butterflys start going the otherway. Wat i mean i they start to close by continuing to rotate upward. So there Actually at WOT at say 95% throttle and that last little bit rotates then upward more actually closing the area off a little, say where they are at 90% throttle. You have to just watch the butterflys to know what im saying if i dont make any sense. It may not even be the problem anyway.

 

[Big flop]

Re: 1995 Johnson "noses over" at full throttle

Take your carb cover off, move throttle lever
to full throttle, look down the carb throat and
make sure the throttle plates are not opening
to far. (not running).
All looks good ? clean carbs.
blow out all passages good, watch for
gummed up main jet, and set the
float levels.

 

[boomer2]

Re: 1995 Johnson "noses over" at full throttle

Just a hunch, pull the cowl off and the cover thats over the carbs. Now watch the butterflys as they open up, are they parallel with the ground at WOT or cocked upward a tab?

Im thinking that they may be all the way open (papallel) slightly before WOT and when you push your throttle to WOT the butterflys start going the otherway. Wat i mean i they start to close by continuing to rotate upward. So there Actually at WOT at say 95% throttle and that last little bit rotates then upward more actually closing the area off a little, say where they are at 90% throttle. You have to just watch the butterflys to know what im saying if i dont make any sense. It may not even be the problem anyway.

Took off the cover and the butterflys are *maybe* tilted upward just the slightest dab too much at WOT. Thanks, will look into it.

 

[boomer2]

Re: 1995 Johnson "noses over" at full throttle

Take your carb cover off, move throttle lever
to full throttle, look down the carb throat and
make sure the throttle plates are not opening
to far. (not running).
All looks good ? clean carbs.
blow out all passages good, watch for
gummed up main jet, and set the
float levels.

Yep..just may be opening a tad too far, the way it looks. Rebuilt both carbs last year and use Seafoam, Evinrude 2+2 ( or maybe 2+4 cant remember) and marine Stabil each time gas is added. Will will take a gander at them (carbs) just to be sure. Thanks guys.

 

[boomer2]

Re: 1995 Johnson "noses over" at full throttle

Now, is it okay to adjust only the butterflys with the main arm that controls them both or is this something like the link/sync that needs to be done step by step and in order?

 

[clemsonfor]

Re: 1995 Johnson "noses over" at full throttle

Now, is it okay to adjust only the butterflys with the main arm that controls them both or is this something like the link/sync that needs to be done step by step and in order?

No your right, adjust the main connected linkage that controls the butterflys. Set the throttle to WOT then adjust the butterflys to parallel. That is basically part of the link n sink. Also at idle make sure they are completly closed as well. That is the link and sink, well part of it.

 

[boomer2]

Re: 1995 Johnson "noses over" at full throttle

No your right, adjust the main connected linkage that controls the butterflys. Set the throttle to WOT then adjust the butterflys to parallel. That is basically part of the link n sink. Also at idle make sure they are completly closed as well. That is the link and sink, well part of it.

Okay. Now if these severe thunderstorms will pass I will take it to the lake and see how it goes..I went ahead and done a link/sync.

 

[clemsonfor]

Re: 1995 Johnson "noses over" at full throttle

just got back from the lake myself. A successful testrun after replacing the stator and flywheel on my 60hp.

 

[boobie]

Re: 1995 Johnson "noses over" at full throttle

If the butterflys go OVER center when at wot this can cause the prob you have.