550XP dying/bogging at initial throttle application

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JackBurton

ArboristSite Lurker
Joined
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Location
Indiana
Hi all.
So I picked up a very lightly used 550XP early Spring as a smaller alternative to my 359. Love the weight and power.
Initially it had a few hiccups where if I didnt mash the throttle, it would die. It would always fire right back up.
I attributed it to the AT learning. I tried a few things too that Id read here about resetting it, and that didnt work.
I had the local dealer look it over, and the only thing they could come up with after having it for a week, and tearing it down to do a bunch of other tests, was that maybe I had the wrong mix in it.
On their suggestion I ran only Huskys oil from there on.
It still had issues but not quite as bad, so I just lived with it.
The last two weeks though, Ive been using it extensively to clean up some storm damage, and its become a royal pain.
Restarting for every third cut is way past getting old.
The saw is excellent when its actually cutting, but its idle seems to have a few problems.
Maybe this is why the original owner was selling at such a good price...

A bit of info on my use, or how I run it. Im not sure its much different from anyone else, but could be, although I cant see how it would cause any issue with this saw, and not any others.
Before I start a cut, I bring up the RPM to about 50%, maybe a bit less. As soon as I touch the wood, full throttle.
Sounds stranger than it actually is in practice.
This initial light throttle application is what is causing the saw to die.
If I give it full throttle, it will sputter a bit, then go.
It really shouldnt sputter either, though, so I assume that too is part of the problem, or maybe whatever is causing that IS the problem.

I spent the last hour or so searching here for a solution, and it seems like most of the threads Ive found are at least a year old, and I didnt see anyone mention a known fix for this.
I have seen a few mention replacing the carb fixing some peoples issues.

Is there a known fix for this?

I am not a saw mechanic, and certainly not with the AT saws.
I am not sure my local dealer knows what they are doing with it, as they didnt even have the proper cord to check/update the AT initially.
I believe this time around I will send it off to someone who knows these things inside and out, like Spike.
Hate to have to do that, but I also really dont like paying someone twice for the same job, and feel like doing that would be a benefit in the long run.
 
There has been updates to the firmware on the carb, you'll need to take it to a decent dealer and have them reflash the ecu. It should take care of the problem.
 
There has been updates to the firmware on the carb, you'll need to take it to a decent dealer and have them reflash the ecu. It should take care of the problem.
Therein lies my problem.
I guess I need to find someone to send it to.

I had to get a new carb on mine.
Just the carb or the electronics too?
I read a few that said just the carb alone fixed it, which is why Im asking.
 
@spike60 can help you out on the programming or new carb if you can't find a local dealer.

There is also a magical mystical screw on those carbs that can help sometimes, it's hidden under a welch plug on the air filter flange.

Also, I've found bending the linkage rod between the main throttle and the stratos throttle shafts to bring the stratos in faster helps with bog or part throttle running issues. I find that the stratos throttle blade doesn't even get to full open when the main is WOT. So I bend the linkage wire to shorten it and make it hit full open as well which also make them open a little sooner in the throttle stroke.
 
Well, looks like I may end up needing to tackle this on my own.
Spike60 doesnt accept work sent it, and I completely understand that.
In my researching of this issue, it appears a replacement of the carb, and necessary updates to it, along with maybe the fuel line, since its a different length for the newer carb than the old, will fix this issue.
Considering the price Ive found with programming, it seems a worthwhile investment that might be worth giving a shot. Shipping two ways would be half the cost of that, so not much more, and I dont mind working on my own stuff, I just cant do the updates, but if they are done before I get the carb...well, thats one less problem.
Everyone Ive come across whose replaced their carb with the updated version reports the problem gone, which is what Im after.
 
Meant to update this a LONG time ago, but forgot.
Ordered a carb that had current updates applied before shipping.
Got it installed easily, and the saw has been working beautifully since!

Now to decide if I want to run 3/8 or just stick to .325...
 
It's nice to see a post with what the solution is.
Yep. I see posts on forums all the time with questions, possible solutions and no follow up from the OP.
Even though I had every intention of posting the results, I darn near ended up that same guy!
Better late then never I guess!
 
Jack, how much was the carb and where did you get it, Thanks.
What part of Indiana are you?

It was $115 if I recall, bought from a seller on ebay.
At the time, that was the best deal I could find.
Hated to spend it, but since I got a smoking deal on the saw, it was a bit easier to stomach. Plus a saw that doesnt run well is a PITA.
Husky should have offered a solution to the problem, since it seems to be very common with the early 550XPs. Im guessing thats why I got such a great deal on the saw. The original owner probably didnt like it dying out all the time.

Near Kokomo.
 
Had to do the same with my 550, had a thread on it and a video. The 550 has had 4 carb models I know of. AT1, AT1A, AT7 and the AT12. Most of the issues seemed to be fixed with the AT12 and newest firmware. The other issue was, many saws with the AT1 and AT1A carburetors also had multiple problems. Air leaks, some had pistons and cylinders with improper tolerances, incorrectly installed components, among other things. So often it wasn't so simple as just replacing the carburetor to get a saw running correctly.

Glad you got your saw going, it sure can be frustrating sometimes, especially on a saw that doesn't have much time on it, or any.[emoji111]
 
Send it to me and ill make her real mean for ya! Glad you got it running at the least.
 
On mine the carb to intake bolts were loose after break-in. One thing to consider looking at.
The intake strato boot on mine was folded inward, zero seal. The transfer o rings were deformed as well, so poor sealing there as well. IMHO QC was non existed at the time, as the saw had massive are leaks so it was never tested at the factory, or properly inspected. The 550 has had a rough rough history as has the 562.

https://r.tapatalk.com/shareLink?ur...share_tid=304293&share_fid=16367&share_type=t
 

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