15 hp Johnson - Throttle

[gamarines2]

My tiller throttle is mechanically frozen. I can see the first linkage torquing, so it is not from there forward. I have ensured that the motor is not in gear, but that shouldn't stop the throttle from moving anyway, right? THis is probably something simple (it worked last time I used it just fine). Where do I start?

 

[HighTrim]

Re: 15 hp Johnson - Throttle

What motor are we talking about to start?

 

[JB]

Re: 15 hp Johnson - Throttle

My guess is that the neutral block in the throttle linkage has moved. That is there to prevent you from revving in neutral and possibly killing yourself when the engine runs away and explodes.

Have you looked under the cowling?

What is the model number?

 

[gamarines2]

Re: 15 hp Johnson - Throttle

Sorry, gentlemen, this is a 1988 J15RCCS.

I have looked everywhere, but if you can tell me what to look for, that would help. I have a pretty good familiarity with this motor, I have recently rebuilt the carb, replaced the head gasket and thermostat. And it has been in the river and running well since those repairs.....now I am stumped about this new problem.

I did remove the propeller to replace with a new one, but that should not have any effect on a "seized" throttle.

 

[OptsyEagle]

Re: 15 hp Johnson - Throttle

I have ensured that the motor is not in gear, but that shouldn't stop the throttle from moving anyway, right?

That would be wrong. What JB has indicated is that there is a neutral block on that motor to prevent the throttle from turning to higher throttle positions when your motor is in neutral. If the throttle was allowed to move to full when your motor was in neutral it would cause your motor to over-rev, then run-away (meaning you cannot turn it off), and eventually explode with piston rods a flying and sometimes accompanied by shrapnel and definitely very loud noise. I might be exagerating a little but I have heard it has happened to earlier models without this feature.

Anyway, you will see this metal piece move as you change gears from neutral to forward and back. It is on the starboard side and catches a piece under the flywheel. Perhaps this is what is catching and if you are in neutral, it is normal.

 

[gamarines2]

Re: 15 hp Johnson - Throttle - Anyone?

Re: 15 hp Johnson - Throttle - Anyone?

I know all about that. What I am telling you all is that my throttle isn't turning AT ALL, not just being limited in neutral. I know about this limiter, it even limits how much you can throttle in reverse. But the big plate under the flywheel isn't turning AT ALL. The throttle cable is fine. I detached it from the linkage connection and it moved freely.

I did notice that my pull-starter assembly was loose. I simply tightened the nut, but now I wonder if it somehow moved out of its proper place and this is somehow screwing with the throttle movement.

Sure sounds like nobody has any experience with this problem.

 

[JB]

Re: 15 hp Johnson - Throttle - Anyone?

Re: 15 hp Johnson - Throttle - Anyone?

You have heard from two helpers, gamarines, in about 24 hours. We have over 300,000 members, but on holiday Saturdays you won't find many active,

Try some patience. Even with the tiny amount of info you offer, someone has seen it before and he will be on sometime in the next few days.

 

[raczekp1]

Re: 15 hp Johnson - Throttle - Anyone?

Re: 15 hp Johnson - Throttle - Anyone?

hi.
my advice is to take of the flywheel, next to take out time platew base and uder timing plare base is friction bearings(no 9).
clean everything an put back oll parts.
here is alink http://www.**********/parts/search/BRP/JOHNSON/1988/J15RCCS/IGNITION/parts.html

next is to clean and grease conection trotle linkage and timing plate base.
the best way to do this is to take airsiliencer and pull start(unscreav siliencer screws, take out upper cover, and inside is 2 smal bolts holding lower cower to carb body.unscreav this.grab slow speed knob and pul out,unscreav pull start mechanism
and dissasemble pull start locker(in my motor i just threw it away) and tkae out pull mechanizs but dont take out the bolt.this bolt should be in all the time.use a tape to tape it around to not loose spring tension.
now disconect trotle linkage and take out aoo patrs and clean after put some grease.
http://www.**********/parts/search/...STEERING HANDLE & THROTTLE CONTROL/parts.html

 

[OptsyEagle]

Re: 15 hp Johnson - Throttle

I have ensured that the motor is not in gear, but that shouldn't stop the throttle from moving anyway, right?

gamarines2, you need to relax. Should I apologize for assuming you didn't know about the nuetral stop when you make statements like this above. Do you understand that it is impossible for others to know what you know and what you don't know on a board like this? You might want to dial down the attitude if you want some help.

Good luck with your motor.

 

[HighTrim]

Re: 15 hp Johnson - Throttle - Anyone?

Re: 15 hp Johnson - Throttle - Anyone?

Sure sounds like nobody has any experience with this problem.

Doesnt make me real eager to type out some help....which we do not get paid for.....at least for every 1 with a statement like this there are 100 that are appreciative.

Good luck with the motor.

 

[gamarines2]

Re: 15 hp Johnson - Throttle

Regret my bad attitude. My apologies to whom I offended. Just frustrated. I have owned this motor for many years and it was always very dependable. I used to joke with my hunting buddies that it was indestructible. Well, then it overheated and then wouldn't run, and I keep running into new problems.....sigh...

This motor has served me well for many years, so I want to keep it, but, yes, it is trying my patience.

Thank you to all of you experts out there that provide such valuable advice. I have received so much information and learned so much over the years. I keep getting demoted, bbut I am not in it for grade....haha....

 

[the machinist]

Re: 15 hp Johnson - Throttle

Here is where I would look.

FIRST as has been mentioned, but not totally clear to a non mechanic, is the motor in neutral? SECOND, I would disconnect the shifting cable from the linkage rod. You can do this by "Popping" the ball coupler on the end of the cable off where it connects to the linkage arm. This will disengage the twist grip cable / throttle assemby. Does the cable move freely now? If so, the THIRD I would try to manally rotate the timing plate under the flywheel either by trying to move the linkage that is mounted on the motor behind where you disconnected the connector ball. Or by trying to rotate the plate itself. This plate is the part that has the carburetor throttle cam attached. If it does not rotate, then you need to remove the flywheel & the plate on the top of the block that the timing plate rotates under. The timing plate has a fiber/nylon bearing ring about 5" in dia. Check this out. No grease should be applied to it as it is really a friction piece that keeps the timing plate from rotating a bit under the influence of the rotatign flywheel.

Somewhere along this line you should find the problem.

 

[gamarines2]

Re: 15 hp Johnson - Throttle

Yes, the motor is in neutral. In this condition, the throttle plate should move about an inch....it does not.

I removed the linkage and the cable moves very smoothly. I can not move the throttle plate manually.

I tried to pull the flywheel.....it's on there pretty good....gave it a good soaking with penetrating oil and will try again another day....

One more observation from tinkering with it some more today. On the port side, there is a red spring loaded 'lever" that, when the drive is put in gear, prevents the manual starter from turning. I noticed that this "lever" is not moving like it should when put into gear. Does that tell anyone anything more about this problem?

Any techniques to remove the flywheel would also be appreciated.

 

[gamarines2]

Re: 15 hp Johnson - Throttle

Just in case, I did use a puller to try to remove the flywheel.

 

[HighTrim]

Re: 15 hp Johnson - Throttle

You will need a harmonic balancer puller with grade 8 bolts.

Thread the puller bolts in evenly, ensuring you do not go too far through though. Tighten down on the puller bolt. I like to leave the nut on a couple turns in case the flywheel flies off. It will pop, just takes some tightening. May need to pull up on the flywheel and give the bolt a rap or two with a hammer. I have never yet needed anything other than this, even with the bigger motors. When re installing, ensure the taper is clean and dry, and torque to spec.

 

[AlTn]

Re: 15 hp Johnson - Throttle

you stated you tightened up the starter screw as it was loose....was it loose enough for the *** on the bottom or the cup to have come out of the hole that it goes into?...if so, it may be possible that your starter is cocked a little and it's interferring with the neutral start linkage

 

[gamarines2]

Re: 15 hp Johnson - Throttle

you stated you tightened up the starter screw as it was loose....was it loose enough for the *** on the bottom or the cup to have come out of the hole that it goes into?...if so, it may be possible that your starter is cocked a little and it's interferring with the neutral start linkage

I was hoping that was the case, but I removed it and reinstalled it and no change. I am still curious what that lever that stops the pull starter from turning when in gear isn't functioning.....

 

[AlTn]

Re: 15 hp Johnson - Throttle

I haven't fooled with that particular starter set up enough to recall exactly ,but it seems there was a red plastic arm that went to the outside of a wire spring arm while a thin metal <?> one went to the inside..I do recall that they had to be on opposite sides and it was a hassle to get it correct with the flywheel on....I removed the flywheel and got the starter straightened out, in fact, I've found that's the easiest way for me < non dexterious> to get the starter back on properly , just remove the flywheel...if you haven't already found The Machinist extensive write up's covering 9.9 and 15 hp. repair..google.. Leeroy's Ramblings....it contains a true wealth of info and pics which may help you now and down the line as well

 

[gamarines2]

Re: 15 hp Johnson - Throttle

Ok, pulled the flywheel and in photo 1 shows what I saw....appears some corrosion. I cleaned it up a little as shown in photo 2. The throttle now turns, but not as easily as before. Should I put some white lithium grease or other lubricant in the area shown by the annotated arrow in photo 2?

 

[jmendoza]

Re: 15 hp Johnson - Throttle

Photos did not load, but, I'm assuming the magneto stator (part with coils) is binding on the boss of the engine block which acts as a bushing bearing for it to rotate on. I would remove the stator plate and clean it and the top of the engine block of all corrosion and lube it with some water proof moly grease. I would then lube the entire throttle linkage as well. Sounds to me like the engine got stored with some moisture trapped under the cowl and corroded up. One thing I do at the end of the season is run my engine in a tank (garbage can) with the cowl off to get it hot and drive off any trapped moisture. After it cools, I spray down the linkages and bare metal with WD-40 as a preventative measure against storage corrosion.