1993 Johnson 115hp slow to plane

[93johnson115]

i am having an issue getting my boat to plane at full throttle. it eventually gets there but takes awhile at times. the rpms are slow to increase. it seems to be worse after the engine is warmed up. this issue started the beginning of this season. i eventually lost my vro pump a couple of weeks ago so i thought that may have been the cause. but it is still happening with the new vro pump so i think it was unrelated??? (it will finally stay running at idle which it has not done since i bought it, 2 years ago, so its not a complete waste!)

i am in the process of replacing all the fuel lines as well as checking compression and doing a decarb (i have not done this for this motor yet). i will post my findings after i do this. i have also noticed that i get a large amount of oil/gas inside the engine compartment and eventually down the outside of the lower unit hence the reason for replacing the lines... maybe i'm pulling air?

any ideas on what else could cause it slow to plane? i thought that when you put the throttle to full the rpms whould jump to the max regardless of what the boat is doing???

thanks so much in advance

 

[countvlad]

Re: 1993 Johnson 115hp slow to plane

i am having an issue getting my boat to plane at full throttle. it eventually gets there but takes awhile at times. the rpms are slow to increase. it seems to be worse after the engine is warmed up. this issue started the beginning of this season. i eventually lost my vro pump a couple of weeks ago so i thought that may have been the cause. but it is still happening with the new vro pump so i think it was unrelated??? (it will finally stay running at idle which it has not done since i bought it, 2 years ago, so its not a complete waste!)

i am in the process of replacing all the fuel lines as well as checking compression and doing a decarb (i have not done this for this motor yet). i will post my findings after i do this. i have also noticed that i get a large amount of oil/gas inside the engine compartment and eventually down the outside of the lower unit hence the reason for replacing the lines... maybe i'm pulling air?

any ideas on what else could cause it slow to plane? i thought that when you put the throttle to full the rpms whould jump to the max regardless of what the boat is doing???

thanks so much in advance

2 years without a decarb or carb rebuild could cause your problems... also fuel running down the lower unit especially from the back of the motor means theres a fuel leak somewhere, most likely coming from the air silencer... take the silincer off.... most of the time fuel will build on the bottom of it so once you take it off youll be able to notice fuel.... all these could cause your problem....

fix check all this and then report back..

btw if you plan to decarb follow the link bellow.... good luck

 

[93johnson115]

Re: 1993 Johnson 115hp slow to plane

thank you count

i am not sure where the fuel mix is coming from. ihave been told it may just be from trailering my boat and having the engine up and the fuel spilling out of the carbs???

where is the air silencer? is that in the lower bottom of the engine...the big bulbous looking "cover" between the exhaust ports? where would it be leaking from in there? is there a gasket?

thanks again for the help.

 

[aclmvh]

Re: 1993 Johnson 115hp slow to plane

The air silencer is the large squarish, shallow 'box' that sits over the throats of your carburetors on the front of the engine (facing the bow).

 

[countvlad]

Re: 1993 Johnson 115hp slow to plane

thank you count

i am not sure where the fuel mix is coming from. ihave been told it may just be from trailering my boat and having the engine up and the fuel spilling out of the carbs???

where is the air silencer? is that in the lower bottom of the engine...the big bulbous looking "cover" between the exhaust ports? where would it be leaking from in there? is there a gasket?

thanks again for the help.

is it leaking around the red circle or black circle???

 

[93johnson115]

Re: 1993 Johnson 115hp slow to plane

thanks acl but i do not have an air silencer just the intake then the carbs. goes along with my thought that the carbs are spilling fuel while trailering.

i did the compression check and the two port side are around 100 and the two starboard are around 120. i did a decarb using engine tuner spraying through the carbs until nearly gone then killed the engine and finished it in each of the cylinders. i let it sit for 3 hours and started it for 15 minutes to blow everything out. i checked the plugs after and a couple had some black "carbon" flakes on them. i looked down the plug ports and the tops of the pistons looked the same as before but it is hard to see in there. wondering if i should decarb it again?

i also think i found the source of the leak. it seems the engine was rebuilt at some point and someone forgot a gasket! i highlighted in red in the picture. it seems to be leaking more so around the starboard side.

thanks again for the help

 

[countvlad]

Re: 1993 Johnson 115hp slow to plane

thanks acl but i do not have an air silencer just the intake then the carbs. goes along with my thought that the carbs are spilling fuel while trailering.

i did the compression check and the two port side are around 100 and the two starboard are around 120. i did a decarb using engine tuner spraying through the carbs until nearly gone then killed the engine and finished it in each of the cylinders. i let it sit for 3 hours and started it for 15 minutes to blow everything out. i checked the plugs after and a couple had some black "carbon" flakes on them. i looked down the plug ports and the tops of the pistons looked the same as before but it is hard to see in there. wondering if i should decarb it again?

i also think i found the source of the leak. it seems the engine was rebuilt at some point and someone forgot a gasket! i highlighted in red in the picture. it seems to be leaking more so around the starboard side.

thanks again for the help

tight the bolts down and go from there..... but man, one side 100 and the other 120 thats not very good... its close to 15% diffrence .... is the 100PSI side the one thats leaking??? if yes then it makes sense.. you were running lean on that side...

tight the bolts down an give it a try.. good luck

 

[93johnson115]

Re: 1993 Johnson 115hp slow to plane

no. the mix seems to be leaking more from the starboard side and the lower pressure is on the port side. port side pluges exhibited more "carbon flakes" than the starboard though. i am going to check compression again and if its not any better i am going to decarb again.

i am excited to get the boat back in the water after all this and see if the slow to plane issue is resolved. wish me luck!

thanks for the help.

 

[93johnson115]

Re: 1993 Johnson 115hp slow to plane

update: i looked at the online parts catelog (brp.com) and the diagram doesn't show a gasket in the area i was talking about (cylinder and crankcase upper and lower). that doesn't seem right to me. maybe someone can explain why a gasket is not needed there????

 

[93johnson115]

Re: 1993 Johnson 115hp slow to plane

well, took the boat out Friday after doing two decarbs and puting in new plugs and it is still no better. spent yesterday rebuilding the carbs but nothing really jumped out at me that was a problem with them. none of the jets/officies were clogged. some of the gaskets may have been leaking but nothing major. maybe the needle valves were sticking open or close. could that be casuing this issue?

i am going to finish the rebuild today and take the boat out for a spin. i have also replaced a majority of the fuel lines... at least the major ones.

if this carb rebuild doesn't work I am at a loss...

 

[93johnson115]

Re: 1993 Johnson 115hp slow to plane

Took the boat out last night and still no better. I looked down the carb throats and there is plenty of fuel going in when I apply full throttle. I am wondering if this could be a timing issue now???

I have broken the issue down to the following; it runs great at idle/slow speed and great at top speed. The issue is getting from idle/slow speed to top speed. It acts like its flooding until finialy it picks up and goes.

Please help!

 

[93johnson115]

Re: 1993 Johnson 115hp slow to plane

FIXED! It ended up being a timing issue. When I looked closer at the spark advance I noticed the adjustment was all the way out on the threaded rod. I recalled earlier this year that the lock nut was loose so I tightened it down where it was. It must have vibrated loose and walked out. I took a chance and moved the adjustment from the end closer to the middle and put the boat on the water. It ran great! I did some fine tuning of the timing by feel on the water instead of actually checking the timing (I don't have a timing gun and I am short on time right now). The boat is running better than it ever has. It peaks at about 5500 RPMs and gets up on plane very quickly with almost no hesitation.

I think I will check the actual timing sometime later but I don't have the time right now.

Thanks all for the help.