Hey guys, i have a 2001 johnson 115 two stroke that is surging at higher rpms.
a bit of a back story, we bought the boat in the fall of last year, didn't get to use in the big motor a whole lot... Late in the year my father thought he was doing me a favor and topped the fuel tank off against my recommendations... I did add stabil and seafoam once home but not sure how well i agitated it.
Once on the water this year playing with the big motor I would have it trimmed all the way down/in and she would launch out of the hole great. once up on plane i couldn't trim very far out without having what i felt was the prop blowing out. It felt like the engine surging and quite possibly it could have been both now that i'm thinking about it. As i'm typing this there were times where when itd happen you could just feel a bit of a slow down vs other times itd about through you into the dash...
Thinking i had a prop problem i ordered a new turning point 4 blade aluminum 13.5x17 prop to replace the 12.75x17 solas which was on the older side it appeared...
The new prop definitely gave me the traction in the water and the ability to lift the bow which i couldn't do with the previous prop...
BUT..... the surging became much more pronounced... right around 4000 and up in rpm's it would surge. even in neutral throttling up to 4000 ish there was 5-600 rpm deviation in the tach... Sometimes the boat would power through and i could get up to the 6000 rpm range but it'd still surge and drop me back down...
I have no fuel water separator (currently at least). I do have a 9.9 yamaha kicker on the back the boat (2001 lund 1700 fisherman) plumbed into what i believe would be the "reserve" line down to my tank. My understanding is there are two lines out of the tank that normally go to a fuel switch, which the PO pulled one of the lines from the switch and plumbed over to the kicker...
The bulb on the main engine with the surging has also never gotten hard. it fills up with fuel but i never feel that it is hard like any of the other bulbs ive ever dealt with...
My question for you guys is... where would you begin to look? I have pulled the plugs, they are all the same condition, white ish brown color but maybe a bit damp... in line fuel filter is clean... I will be pulling a couple pints of fuel out to check it here shortly to see what i have there...
Is there a method to check coils, stator and power pack? does this sound more fuel related or spark related?
any common problems with this era to look for?
Any other thoughts?
a bit of a back story, we bought the boat in the fall of last year, didn't get to use in the big motor a whole lot... Late in the year my father thought he was doing me a favor and topped the fuel tank off against my recommendations... I did add stabil and seafoam once home but not sure how well i agitated it.
Once on the water this year playing with the big motor I would have it trimmed all the way down/in and she would launch out of the hole great. once up on plane i couldn't trim very far out without having what i felt was the prop blowing out. It felt like the engine surging and quite possibly it could have been both now that i'm thinking about it. As i'm typing this there were times where when itd happen you could just feel a bit of a slow down vs other times itd about through you into the dash...
Thinking i had a prop problem i ordered a new turning point 4 blade aluminum 13.5x17 prop to replace the 12.75x17 solas which was on the older side it appeared...
The new prop definitely gave me the traction in the water and the ability to lift the bow which i couldn't do with the previous prop...
BUT..... the surging became much more pronounced... right around 4000 and up in rpm's it would surge. even in neutral throttling up to 4000 ish there was 5-600 rpm deviation in the tach... Sometimes the boat would power through and i could get up to the 6000 rpm range but it'd still surge and drop me back down...
I have no fuel water separator (currently at least). I do have a 9.9 yamaha kicker on the back the boat (2001 lund 1700 fisherman) plumbed into what i believe would be the "reserve" line down to my tank. My understanding is there are two lines out of the tank that normally go to a fuel switch, which the PO pulled one of the lines from the switch and plumbed over to the kicker...
The bulb on the main engine with the surging has also never gotten hard. it fills up with fuel but i never feel that it is hard like any of the other bulbs ive ever dealt with...
My question for you guys is... where would you begin to look? I have pulled the plugs, they are all the same condition, white ish brown color but maybe a bit damp... in line fuel filter is clean... I will be pulling a couple pints of fuel out to check it here shortly to see what i have there...
Is there a method to check coils, stator and power pack? does this sound more fuel related or spark related?
any common problems with this era to look for?
Any other thoughts?
