94 Johnson 48 SPL half speed at WOT

[ziggy101]

I bought this motor last spring that had been setting for about 10 years - supposed to have been winterized and then not used. Had some issues last year, seamed like it was not getting fuel surged up and down RPMs, replaced fuel hose, put in new carb kits last year, and had it tuned up at a shop, they said it needed a power pack. Ran good the last few times out.

I put gas stabilizer in last fall and ran it awhile, but did not fog/drain carbs. Took it out for first time a couple of days ago. It started right up and ran well at idle. But at high WOT it would only go about half speed, it sounded fine - not like it was missing - but i am no mechanic. I took the plugs out when i got home - both looked oily. That's the only investigative work i have done.

Read something about checking spark distance on other posts - is that just holding the plug away from the block and seeing how far it jumps?

Any direction on where to start would be helpful.

 

[BonairII]

Re: 94 Johnson 48 SPL half speed at WOT

Get yourself an adjustable spark tester. Can be purchased at most auto parts stores for $10 or less. You can adjust the distance the spark jumps with these testers.

 

[ziggy101]

Re: 94 Johnson 48 SPL half speed at WOT

I bought a spark tester and got spark on both at 7/16". Also did a compression check and got 135 and 140.

when i started it up and had the issue originally a had a fair run at "no wake" before i tried WOT. since i rebuilt the carbs last year - i am doubting if its carbs. I was also reading about the SLOW circuit and wondered if it could be bad water pump causing overheating and limiting RPM or fuel pump. Any Ideas what to try next?

I probably should change impeller anyway since i did not when i bought this last year.

 

[ziggy101]

Re: 94 Johnson 48 SPL half speed at WOT

after thinking about this i don't believe it could be the SLOW as i started back up after setting for several hours and it still was half speed.

so does this mean fuel pump and then go to cleaning carb (even though this doesn't seam likely)?

 

[ziggy101]

Re: Need HELP - 94 Johnson 48 SPL half speed at WOT

Re: Need HELP - 94 Johnson 48 SPL half speed at WOT

would like suggestions/help

 

[ziggy101]

Re: Need HELP - 94 Johnson 48 SPL half speed at WOT

Re: Need HELP - 94 Johnson 48 SPL half speed at WOT

After further review and conversation with a friend - he asked are you sure the gas is opening up fully there is not something wrong that is preventing the carbs mechanically from getting fully opened (since the engine sounds good).

Come to find out the linkage between the carbs was in the way of the cam attached to the throttle cable. The linkage rod has close clearance between it and this cam. may have got bent when i rebuilt the carbs and pulled it off. i bent it a little and it now clears - i am pretty sure this is the issue. Hope this helps someone else with a similar issue

 

[ziggy101]

Re: Need HELP - 94 Johnson 48 SPL half speed at WOT

Re: Need HELP - 94 Johnson 48 SPL half speed at WOT

Regarding the oily plugs i noticed that the plugs were qL77yc when they are supposed to be QL78 YC. Could this be the reason?

 

[ziggy101]

Re: Need HELP - 94 Johnson 48 SPL half speed at WOT

Re: Need HELP - 94 Johnson 48 SPL half speed at WOT

I am continuing to have problems with this motor not going full speed only less than half at WOT. I have done spark tests, put in new fuel pump checked, and it pumps gas. Cleaned carbs last fall. Replaced fuel lines to the fuel pump. I am wondering - the butterfly's on the carbs are not fully open at full throttle - should they be. It also looks like the carb has two different sets of holes where the linkage ends go in, could it be in the wrong hole?