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streetcore

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Discussion starter · #1 · (Edited)
So I'm trying to help out a family friend who's husband passed away. He had a Stihl HS-45 hedge trimmer that has been sitting for awhile with no gas in the tank that she wants to use. So I told his wife I would bring it home, put some gas in it, and see if I could get it running for her.

I filled the tank, followed the starting instructions in the manual, and it started right away. So I tried it out on one of my hedges to make sure it was working ok. Everything was working fine, so I shut it down and set it on the floor of my garage.

Well, this morning I tried to start it again, but the throttle seemed stuck or jammed and I couldn't open it enough to engage the throttle lock during the start procedure.

I did get it started without engaging the lock, but the throttle still wouldn't open and it just ran at idle or a little above if I moved the throttle as much as I could.

I removed the black cover around the throttle and didn't see any problems with the throttle lever or cable. Then I tried to move the throttle on the carb with my finger, but it wouldn't move.

I removed the cable from the throttle linkage in case it was obstructing something, but the throttle still wouldn't move.

So then I removed the carb so I could inspect from both sides. I can't see any problems, but something is stopping the throttle valve from opening. It opens a tiny bit, but then I feel some resistance.

Has anyone ever seen anything like this? Could there be something inside jamming the throttle? The carb is a Zama C1Q.

That's what I get for trying to be helpful, lol. Hopefully I don't have to buy a new carb.
 
Is it possible that the throttle shaft is gummed up? Maybe take the air filter out and spray a very small amount of carburetor cleaner on the throttle shaft and throttle plate. Try working the throttle while the cleaner is working and see if it frees up. Good luck.
 
That's what I get for trying to be helpful, lol. Hopefully I don't have to buy a new carb.

I have seen this on Walbro carbs. The screw that holds the throttle plate in place will back off or disappear into the engine, allowing the plate to move or get caddywhompus in there.
Take a thin long screw driver and poke around in there, if the plate moves, just tighten up the screw if you can find it. Hopefully that will solve your problem.
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Discussion starter · #4 ·
Thanks for the replies. The throttle shaft was definitely restricted by something. After looking at parts diagrams and rebuild videos I figured I couldn't really hurt anything if I applied a little force to it. It took a bit of effort to move it with my fingers, but I eventually got it open. Then I worked it back and forth for awhile and sprayed it with some carb cleaner. It would still stick wide open sometimes after that, but I put carb back on machine and it started and ran ok.

I continued to work throttle open and closed for several minutes, but it would still stick wide open sometimes. So I applied a bit of PB Blaster on both ends of throttle shaft and left it to sit over night.

Checked it this morning and it feels better now and didn't stick open at all. So strange that it was working fine one day and then stuck the next, but at least I can return a working machine to the lady. I will warn her that the throttle was sticking and offer to replace carb if she wants to pay for the parts.

Thanks again.
 
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