Throttle Sitcks?

[merrile]

I have 33 HP, 65 Evinride outboard. My issue is when I rev the motor it will not return to idle. I have verified its not the cable as I was controlling the throttle directly by hand. It will shut off if I pull the choke. Any suggestions? It seems to stick right at a certain point (just above no wake). How should I approach this? Carb?

 

[marinemech1]

Re: Throttle Sitcks?

Manually advance and retard throttle...does the little wheel follow the cam (under flywheel)? Or does it stick part way?
You may have a binding throttle.
Wayne

 

[Joe Reeves]

Re: Throttle Sitcks?

Remove throttle cable from engine, remove spark plugs, spin prop and put engine into forward gear.

Now, slowly advance the throttle linkage by hand where the throttle cable would normally connect. Observe closely all operations pertaining to the throttle and timing, that is the armature plate under the flywheel, the linkages leading from the armature plate to the throttle cam roller, the throttle butterfly, etc.

Something is apparently sticking..... just a matter of locating the problem area.

Pertaining to the throttle cam actuating rod that leads from the armature plate to the throttle cam roller...... that has a critical adjustment as follows.

(Synchronization Of Older 2 Cyl Engines)
(Such As The 28, 33, 40hp Etc models )

On the linkage that runs from the armature plate (the plate the coils & points set on) to the carburetor throttle roller, loosen the set screw on the brass collar that you see there and temporarily move it away from the armature plate/vertical throttle arm clevis (clevis is that thing the linkage rod slides through). We'll refer to that vertical throttle arm/armature plate clevis simply as the "clevis" from this point on.

Look at the cam that's attached to the front of the armature plate.... the cam that slides up against the carburetor throttle roller. You'll notice that there's a scribe mark on it. The carburetor roller should contact the cam and just start to open the throttle butterfly when that scribe mark is dead
with the roller.

With the engine in gear (not running of course) have the armature plate advanced all the way (by hand) so that it is up against its stop. Now adjust the brass collar (set screw) on that associated linkage rod so that it is up against the clevis. It should be adjusted so that there is either no play, or just a hairs play between the collar and the clevis.

At this point, the armature plate movement is not advancing the throttle butterfly via the rod movement, but further movement of the throttle control, although the armature plate cannot move any farther, causes the tension spring at the armature plate to allow the vertical throttle arm to move farther which now advances the carburetor throttle butterfly via the rod.

If all else with your engine is as it should be, that should do it.

 

[merrile]

Re: Throttle Sitcks?

wow!!! I am going to read that a coulple of times but I see where your headed with this.

 

[Joe Reeves]

Re: Throttle Sitcks?

Might be a good idea to print it out.

 

[merrile]

Re: Throttle Sitcks?

I should probably mention that if I kill the motor and restart Its goes right to idle. So when advance he throttle by hand it revs up I adjust by hand it back to where idle should be and it stays at the higher rev point. Kill the motor, restart its back to idle and the process will repeat itself. Does you previous post still apply?

 

[lindy46]

Re: Throttle Sitcks?

As stated above, take the cover off and OBSERVE what is happening when you accellerate and decellerate. Something is sticking/binding - you should be able to see it, as it is a very simple mechanism. Make sure the cam roller return spring is in place.

 

[merrile]

Re: Throttle Sitcks?

still can't figure it out. even when I manually adjust that arm below fly wheel while running, it still sticks. I guess I just don't undertstand the throttle systems on the old motors .

 

[F_R]

Re: Throttle Sitcks?

merrile, I have to wonder: Are you speaking of an actual sticking condition, or are you speaking of a won't slow down condition? If the latter, are you running it on a boat, in the lake, and in gear when this is happening? It sort of sounds like you are not.

If you rev it up beyond a certain point with no load on it (in neutral or out of the water) then something called "runaway" happens. In a runaway condition the motor keeps on running fast and won't slow down. It is a completely normal thing.

BUT, and I repeat, BUT the motor has a device called a vacuum cut-out switch that senses the abnormally high vacuum in the intake manifold during runaway and kills the ignition on one cylinder when runaway occurs. That allows the motor to slow back down, then the switch opens and it continues to run normally on both cylinders.

In order for the vacuum cut-out switch to do its job, of course it first has to be there and functional, and it has to be correctly connected. Which brings us to the second switch, the safety switch. The vacuum cut-out switch is grounded by the safety switch, but only when in "slow" throttle settings. That prevents it from cutting out one cylinder when you don't want it to.

The system is quite effective, but only works if it is there and functional.

 

[merrile]

Re: Throttle Sitcks?

that makes allot of sense then. I did run it on the water and I got run away however, there is not kill switch working at the moment so for what I read I must address that first correct?

Eric