582 carb slide stuck open

[dholly 718]

Anyone have this happen?

[Dave B 0]

Anyone have this happen?

There's a possibility, if the needle clip is INSIDE the plastic cup, that the end of the needle will fully come out of the needle jet and catch on the side. Make sure the needle clip is BETWEEN the plastic cup and slide.

Other than that, dirt, or cable problem.

Let us know.

Dave

[dholly 718]

Thanks, I'll be taking a close look this weekend hopefully.

[dholly 718]

Well here's the deal. I had what I thought might have been a stuck slide. I pulled the throttle back and nothing much happened. I tried to cycle the throttle. Unfortunately, that only left me with a wide open throttle. I ultimately had to shut the runaway train down with the ignition key. In a simple post event field check, I found the front carb felt 'sticky'. By that I mean when pulling up on the throttle cables at the top of the carbs, rear was free but not the front. I didn't do any further in-depth engine checks until yesterday, in part due to the plane being at the A&P's for a damage appraisal (which, from my new sig line courtesy of fearless leader Leni, you can correctly surmise went rather poorly).

So yesterday I opened up the carbs and found nothing unusual looking at all. The cup was sliding fine in the front carb and the disconnected throttle cable worked smoothly as it should. Return spring pulled throttle closed fine. Basically, I was kind of stumped and at a loss as to what the heck happened. Not to the point of questioning whether some type of malfunction had actually happened, it most assuredly did, but I started wondering if I was going to have resolution. I HATE when stuff happens and you can't pinpoint the source, leaves that lingering doubt in the back of your mind about mechanical reliability.

As I discounted any problem with the carbs themselves I started working my way back from the carbs along the cables to the throttle in the cabin. Again, no binding or friction problems at all with the carb ends disconnected, but something did catch my attention. When I bought the plane, both throttle cables were zip-tied to the engine mount between the firewall and carbs. I didn't think that was unusual, as I've always mechanically secured cable sheaths multiple times to keep internal cable function in the event one clamp fails. What I did notice was that it was very slightly loose and I could move it up or down along the engine mount tube. Here's some pics.

You can see from the black overspray on the engine mount tubing just how far along the tube I could slide the zip tie. When I first noticed it, the zip tie was at the bottom most position. When I reattached the throttle cables at the carb end and operated the throttle, moving the zip tie up and down the tube to various positions it became clear it impacted the function of the cable ends at the carbs. As I understand it, the zip tie somehow slid/vibrated down the tubing which had the effect of shortening the working length of the cables. This had little effect on the rear carb closest to the firewall, but put just enough stress on the cable path into the front carb to create friction and preclude the carb slide from closing. With the zip tie removed, all throttle and carb operation function perfectly. An expensive lesson for me, don't you make the same mistake.

Regards,

Killer

[akflyer 1427]

Doug, this sucks! I wonder if the inner liner was cut through on the cable. The zip tie moving should not make the cable hang up unless it is frayed inside. Mine is routed kind of like yours, so when i get home I am going to check out my cables. It sucks that it cost you the bird, but I hope your lesson can help others out and maybe save someone else from ruining a perfectly good pair of shorts! Oh, and a good plane too