1997 Johnson 115hp outboard

[Bholub36]

morning gents,

just bought a used pontoon this week with a known engine issue. it has a 1997 johnson 115hp outboard on it. the guy i bought it from put a lot of time into trying to figure out this issue and never got it resolved. the deal on the boat was too good to pass up so i bought it. i have confidence that its not a major issue and something is just getting looked over. i also know with the knowledge of this site that somebody will have had and or seen this problem before...

here is whats going on....engine starts and runs great. 2 pumps of the primer bulb and it gets rock hard, turn the key and it starts right up every single time. idles good, runs low rpm fairly well...there is a little bit of a hesitation when going from no wake idle cruise up to just past that. once past the 1.5k rpm mark its nice and smooth. the major issue that im having is mid to high rpm. it runs super smooth, then about every 30 sec it will buck. almost like the engine completely shuts off for just a split second, and comes back on. then smooth again. 30 sec goes by...then boom, one single buck, then smooth again...30 sec later boom. a buck, then smooth again....ect you get the idea. idle it down to around 2500rpm and no issues.

it has had a new power pack, plugs, wires, fuel line with primer bulb, stator, rectifier, coil packs, carbs cleaned, 120 psi compression on all 4 cylinders, new fuel pump with VRO delete, timing sensor.

could it be something in the carbs even though they have been cleaned? im stumped....let me know your thoughts!

thanks fellas!

 

[racerone]

There are 2 different model 115 HP motors.-----My bet is a lower unit issue.----Jumping out of gear.-------Look into checking the shift rod height.-----A " no money spent " inspection !!-----Throwing parts at a motor often does not work.

 

[Bholub36]

i forgot to mention, the lower unit was pulled and inspected. all the gears looked really good. the previous owner did say that he thinks the shift cables are out of adjustment. to get the boat in reverse i basically have to pull the throttle all the way back, and at that i have may 1-2in of throttle left for reverse gear. forward gear i barely move it forward from neutral and it goes right in. could that make a difference with the shift rod you speak of? is there some sort of guide on adjusting the shift cables? i know i/o motors the shift adjustments make a massive difference. is there a specific way to check the shift rod height and adjust it?

im new to outboards, but very mechanically inclined.

 

[racerone]

You forgot to mention that lower unit has been inspected ?

 

[Bholub36]

sorry, was trying to remember everything the previous owner said he had done.

 

[Bholub36]

anyone have any other suggestions? i will be removing the lower unit this weekend and checking the shift rod for correct adjustment. i also found last night that the shift cable was not adjusted correctly as well. when lower unit is in full neutral should the mechanism that the shift cable connects to be perfectly vertical?

thanks everyone

 

[racerone]

That should be near vertical.

 

[Bholub36]

ok. i would say it was probably was about 1/4 off from vertical. would anyone happen to have the spec for at 1997 johnson 115hp G04287742 for the shift rod? looking to pull the lower unit this weekend to check the shift rod adjustment.

i think racerone you are spot on with what the issue is with this boat.

thanks again!

 

[racerone]

What is the MODEL # of your motor ?----Or post pictures.

 

[Bholub36]

Here is a pic

 

[racerone]

That would be the 60 degree looper model.----Post a picture of the lower unit from the side.

 

[Bholub36]

[No message]

 

[racerone]

That does not look like an EXACT replacement for a 90 degree motor.----So the mystery deepens.----But I can not tell for sure.----What is the part number etched on the driveshaft ?

 

[Bholub36]

I wont know until i pull the lower unit. I brought it home from the slip today so i can pull it. Im assuming its probablu and evinrude lower unit thats been installed on the Johnson?

 

[racerone]

No----It is not the right shape for a looper lower unit.----Nothing to do with the colour !!

 

[Bholub36]

Hopefully that doesnt mean that getting the adjustment correct is going to be a guessing game. If i get the driveshaft numbers will that help with gettitng the correct tolerances for the adjustment?

 

[racerone]

All I can say is for you to do the investigating on this.

 

[Bholub36]

[No message]

 

[Bholub36]

Driveshsft numbers are 338573

 

[racerone]

DIstance from mounting surface to end of driveshaft is ?-----In neutral distance from mounting surface to center of shift rod hole is ?----Pictures of the end of the shift rod.