Strange throttle issue 1996 Suzuki 2.5

[SVSOLITAIRE]

Having trouble with my dinghy motor.

1996 Suzuki 2.5 hp model #NS2.5A

Motor generally runs great aside from fuel/carb issues from time to time.

I just did a full service
-carb cleaning
-spark plug
-trans fluid

Issue. The throttle lever will not stay stay at medium or high throttle. It’s not a matter of the lever vibrating itself down. It seems as though the plunger on the throttle body keeps springing down. I didn’t actually open the throttle body yet but did clean the plunger stem and tested movement etc. When I pull it up it sucks itself/springs into a idle/slightly higher than idle position.

The only thing I’ve done out of the ordinary maintenance is add some sea foam to the fuel mix. (50/50 mix).

Does anyone have any insight on this issue?

[tkeithlu]

#5 on your exploded view is the throttle return spring. It appears that you cleaned up well enough that it actually works. Plenty of small engines have throttle return springs that don't work; on my antique motorbikes it's called "CT-90 Cruise Control."

[SVSOLITAIRE]

Originally Posted by tkeithlu

#5 on your exploded view is the throttle return spring. It appears that you cleaned up well enough that it actually works. Plenty of small engines have throttle return springs that don't work; on my antique motorbikes it's called "CT-90 Cruise Control."

I totally get the concept but does that make the assumption that the driver is to hold the tiller and throttle while motoring? Seems dangerous, not to mention annoying. I used a flat head screwdriver to hold it mid throttle today but that seems like a silly permanent solution.

[SVSOLITAIRE]

Originally Posted by SVSOLITAIRE

I totally get the concept but does that make the assumption that the driver is to hold the tiller and throttle while motoring? Seems dangerous, not to mention annoying. I used a flat head screwdriver to hold it mid throttle today but that seems like a silly permanent solution.

I guess a better question is can I remove the spring without compromising function?

[tkeithlu]

The spring return is a safety feature. Have you seen YouTubes of outboard boats spinning in circles with no one on board? Those engines have throttle return springs that don't work; if they did, the engine would drop to idle when the throttle was released. The other allied safety feature is the kill switch, which the skipper of said boats was not waring around his wrist when he was thrown out of the boat, probably by gunning the engine while it was hard over to port or starboard. But then, outboards with remote controls usually don't drop to idle when you take your hand off, leaving only the kill switch.

At any rate: If you're prepared to bypass this safety feature, consider adding friction to the throttle linkage. A sophisticated alteration would include an adjustable friction screw, such that you could set the throttle once straightened out, as you do cruise control.

Whether you could just remove the spring would depend on the linkage. It may be that the linkage is pull (more RPM) only, with the spring there do the returning. Alternately, it may be pull and push, so it would work, but probably be very sloppy. I can't really tell from the exploded view.

Do use the kill switch cord.....

[SVSOLITAIRE]

Originally Posted by tkeithlu

The spring return is a safety feature. Have you seen YouTubes of outboard boats spinning in circles with no one on board? Those engines have throttle return springs that don't work; if they did, the engine would drop to idle when the throttle was released. The other allied safety feature is the kill switch, which the skipper of said boats was not waring around his wrist when he was thrown out of the boat, probably by gunning the engine while it was hard over to port or starboard. But then, outboards with remote controls usually don't drop to idle when you take your hand off, leaving only the kill switch.

At any rate: If you're prepared to bypass this safety feature, consider adding friction to the throttle linkage. A sophisticated alteration would include an adjustable friction screw, such that you could set the throttle once straightened out, as you do cruise control.

Whether you could just remove the spring would depend on the linkage. It may be that the linkage is pull (more RPM) only, with the spring there do the returning. Alternately, it may be pull and push, so it would work, but probably be very sloppy. I can't really tell from the exploded view.

Do use the kill switch cord.....

Though I see what you mean this just seems insane given this particular motor. So I have to use both hands to drive while facing the motor. That seems entirely unsafe. I’ll have to look into specifics on this make but ergonomically speaking it makes absolutely no sense. I do where my kill switch attached to a utility belt I wear. I think they passed legislation last year in Florida that makes attaching it to yourself the law.

[Boatyarddog]

Originally Posted by SVSOLITAIRE

I guess a better question is can I remove the spring without compromising function?

Is the throttle speed adjusting screw or mechanism on the handle not working or loosening up.
My understanding of your issue is that the throttle won't stay by its self in a medium, or other position by itself other than idle?
Tiller handle returns to idle?
Tighten the handle screw throttle tension adj? https://image.slidesharecdn.com/suzu...?cb=1323947709
SV Cloud Duster

[SVSOLITAIRE]

Originally Posted by Boatyarddog

Is the throttle speed adjusting screw or mechanism on the handle not working or loosening up.
My understanding of your issue is that the throttle won't stay by its self in a medium, or other position by itself other than idle?
Tiller handle returns to idle?
Tighten the handle screw throttle tension adj? https://image.slidesharecdn.com/suzu...?cb=1323947709
SV Cloud Duster

So this is an old motor. It has a lever throttle which is separate from the tiller handle. It’s highlighted in that cut away. The issue is the lever will not remain in a position higher than idle.

A valid point was made about the spring all of the sudden functioning, the only issue I see is that functionally it doesn’t make sense to have a spring throttle safety with this particular model engine. The issue was less severe today. I’m inclined to think it will return to normal function. The sea foam I added must have been causing heavy particulate removal or a variety of other possibilities.

[Sailmonkey]

Originally Posted by SVSOLITAIRE

So this is an old motor. It has a lever throttle which is separate from the tiller handle. It’s highlighted in that cut away. The issue is the lever will not remain in a position higher than idle.

A valid point was made about the spring all of the sudden functioning, the only issue I see is that functionally it doesn’t make sense to have a spring throttle safety with this particular model engine. The issue was less severe today. I’m inclined to think it will return to normal function. The sea foam I added must have been causing heavy particulate removal or a variety of other possibilities.

I’ve got a 2hp mariner with the same setup. There is friction applied by screw #31 (or something near it in your diagram). Tighten it enough to keep the throttle where you set it. These engines are not intended to be two handed operation.

[SVSOLITAIRE]

Originally Posted by Sailmonkey

I’ve got a 2hp mariner with the same setup. There is friction applied by screw #31 (or something near it in your diagram). Tighten it enough to keep the throttle where you set it. These engines are not intended to be two handed operation.

Copy that! Thanks you. I probably unintentionally loosened it while cleaning.

[Boatyarddog]

Originally Posted by SVSOLITAIRE

I guess a better question is can I remove the spring without compromising function?

Ns2.5a, found the info under the Nissan brand.https://www.nissanoutboardparts.com/...2N21023-3).pdf

Don't think you can disable the spring since its your only means of lowering the RPMs, not push pull. Seems to have a "wire" Assembly to connect the two.
Possibly tighten the lever screw so you have some friction holding the lever for you. Even nylon washers each side of the lever for friction points. The PDFs show throttle lever gaskets both sides of your lever pivot points, I'm pretty sure these are your friction "discs".
As mentioned tightening the #31 screw should help.
Good luck
SV Cloud Duster

[SVSOLITAIRE]

Originally Posted by Boatyarddog

Ns2.5a, found the info under the Nissan brand.https://www.nissanoutboardparts.com/...2N21023-3).pdf

Don't think you can disable the spring since its your only means of lowering the RPMs, not push pull. Seems to have a "wire" Assembly to connect the two.
Possibly tighten the lever screw so you have some friction holding the lever for you. Even nylon washers each side of the lever for friction points. The PDFs show throttle lever gaskets both sides of your lever pivot points, I'm pretty sure these are your friction "discs".
As mentioned tightening the #31 screw should help.
Good luck
SV Cloud Duster

Bringing out the big guns!! Thank you!