Problem with Husqvarna 254 throttle mechanism

[hymek]

When I release the throttle on my Husqvarna 254XP it goes to half throttle rather than returning to idle as it used to do. If I touch the component ringed in the above photo, it will return to idle, but the throttle rod doesn't seem to have enough tension or natural momentum to trigger the idle position on its own. Besides replacing the throttle rod and plastic guide piece it sits in (both of which are pretty old and worn) does anyone have any idea how I might go about fixing this issue? Any suggestions would be much appreciated.

Thanks,
Tim

 

[Bob Hedgecutter]

Sounds like the return spring has broken- or the captured end of the spring has jumped out of position.
Has the carb been off lately, or any repairs/cleaning been done recently?

 

[hymek]

Thanks for responding, Bob. I've cleaned the carb area fairly recently so may have accidentally dislodged or broken something. The return spring seems to be intact and functioning, but maybe it's now just too weak to do the job properly (It's probably at least 30 years old). I might try inserting a stronger spring if I can find something suitable.

 

[Bob Hedgecutter]

I would disconnect the throttle rod and see if the spring enables full travel without the rod attached- if it is still sticky- either the spring has jumped- or the throttle plate is catching internally.
To verify if the plate was catching, I would remove the carb and check operation off of the saw.

 

[hymek]

Thanks. Having done some testing, I've come to the conclusion that the problem isn't the throttle rod or return spring but is related to the component (ringed in attached pic) that links the choke switch to the throttle. With the choke pulled, the throttle rod has full travel. However with the choke pushed in, the throttle always 'catches' at half throttle when the trigger is released rather than returning to idle. Pumping the trigger doesn't help.

I guess I'm going to need to remove the carb (something I've not done before on a saw) and see what's going on in the place where the throttle 'spindle' connects with the linkage from the choke switch.



EDIT. After feeling about under the carb with a small screwdriver I think I've managed to fix the issue. There's a spot where a small sprung metal component connects to the plastic choke linkage, and by pushing it back while working the choke I seem to have restored normal service. Saw now returns to idle when trigger is released.

 

[Bob Hedgecutter]

Sounds like somehow you managed (whilst cleaning) to misalign the fast idle feature and once choke was engaged to activate the fast idle for cold starting- it was unable to return once trigger applied and choke released.

Good you figured it out.