562xp warm start trouble, air purge stops working for a while

[Solrael]

Thanks so much for the idea! I'll try that this week (I ended up spending the whole weekend log splitting instead).

 

[Big_Wood]

My 562 does this sometimes as well but very rarely. My fix is to pin throttle wide open and do the push pull start holding onto the rear handle. Works every time if it fails to start with high idle. As far as the 550 goes, brad I think started a thread on a air screw between the carb body and filter holder which is behind a welch plug. Open that up 1/4 turn has fixed quite a few for me.

 

[Solrael]

I tried the small o ring idea (stacked two on there), I thought at first it had made a difference to the first round of cutting (from a cold start), but I think it just runs better with my 24" bar. It still had the same problem on warm starts.

One thing I noticed, when the primer isn't working you can put your ear up to it and hear what sounds like a little pin hole leak that just keeps going. I pulled the line from the carb to primer and the bulb works fine (made a good vacuum with my finger over the house). The noise stops when you do that, but a few pumps after the line is back on the noise returns.

Any other ideas? Does the fuel line go straight to the tank or could there be something on that side of the carb for me look at? Is the check valve inside the carb serviceable, or would I be replacing the whole carb? Am I still misunderstanding vapour lock? (I open the tank every time the primer isn't working but nothing seems to change).

 

[Topbuilder]

I have had to replace my whole fuel line and bulb assy already. Less than 2 years old. Similar symptoms. I had never used E-10 Gas. I NEVER use decomp anymore. Trashed a recoil assy.

 

[MountainHigh]

My late model 2013/el46 carb 562xp is just starting to do this same thing regularly after light use and ZERO previous issues ...

I run 40 to 1 non-ethanol gas mix (stabilized and never older than 3 months), drained after each use, but have also run 50-1 Husky pre-mix on occasion and saw compensated flawlessly.

My situation:
~ I usually press purge bulb about 10 times - push decompression in - cold saw blips on 2nd or 3rd pull using choke, one or two more pulls and she's running. I let her idle high for appx 10 seconds or until no hesitation on throttle blip.

~ Cuts wood like rabid banshee as she gets good and hot - idles fine in between logs - no hesitation and no worries!

~ Turn saw off and place aside for a few minutes in order to roll logs, setup for another tree fall and/or take break

~ After a few to ten minutes. I pick up warm 562 and use Hot start (choke UP then Down, which always worked fine before) with decomp button pressed in, and pull till the freaking cows come home - Nadda! Purge bulb not filling with gas, and fizzy pressure released from Gas tank when gas cap opened. I've also tried non-hot start/regular start, tried choking it, and also tried starting with wide open throttle with inconsistent and disappointing results!

~ Mutter few choice swear words, put the saw aside and pick up my near antique 346xp.

~ Come back after all wood is cut with my 346 (maybe 3/4 hour) and try the 562 again with high idle and/or choke if at least 30 minutes have passed, starts and runs fine as usual.

Peak firewood scrounging season and I'm taking it in for service on warranty

 

[Chris-PA]

It could be an air leak into the fuel system somewhere, but it sounds exactly like the vapor lock I deal with all the time. However, I run E10. Some saws I can get going again with full choke and a lot if nursing, but other not until they cool down.

How sure are you that there's no ethanol in your fuel? This time of year the fuel is probably still winter blend with added butane for easier vaorization in the cold, which is a problem when it starts getting warm even without ethanol.

 

[MountainHigh]

It could be an air leak into the fuel system somewhere, but it sounds exactly like the vapor lock I deal with all the time. However, I run E10. Some saws I can get going again with full choke and a lot if nursing, but other not until they cool down.
How sure are you that there's no ethanol in your fuel? This time of year the fuel is probably still winter blend with added butane for easier vaporization in the cold, which is a problem when it starts getting warm even without ethanol.

Interesting .... up here we can buy ethanol free Shell 91 octane , Chevron 94 Octane and this time I bought Costco 91 Octane. This is the first time I bought Costco 91 and specifically asked - they assured me it was non-ethanol. I do recollect that I've had same hot start thing happen with previous 91 Octane from Shell as well.

Do you run into issues where your purge bulb just doesn't fill (like mine) when Hot start is acting up?

 

[Topbuilder]

I don't know if this will help your situation, when hot starting, I do not purge or use the decomp button. I just choke UP then Down and pull start.

 

[MountainHigh]

I don't know if this will help your situation, when hot starting, I do not purge or use the decomp button. I just choke UP then Down and pull start.

Thanks, I'll give the no-purge and no-decomp-button a try mid week one last time before taking it in. I suspect with no fuel increase showing in the purge when used previously, it may be more about an air leak, but I'll give anything a try for sure.

How's your shoulder holding up with no decomp use? if that's the solution this saw is going to be idling an awful lot.

 

[Topbuilder]

How's your shoulder holding up with no decomp use?

No problems. I was blessed with a strong back and a weak mind, er , I think

 

[Chris-PA]

Interesting .... up here we can buy ethanol free Shell 91 octane , Chevron 94 Octane and this time I bought Costco 91 Octane. This is the first time I bought Costco 91 and specifically asked - they assured me it was non-ethanol. I do recollect that I've had same hot start thing happen with previous 91 Octane from Shell as well.

Do you run into issues where your purge bulb just doesn't fill (like mine) when Hot start is acting up?

Yeah, the purge bulb is useless - essentially the fuel is at or close to boiling, and when you press the purge bulb it tries to pull fuel through the carb. This means it is reducing the pressure and the fuel boils instantly. Also why the carb can't pull fuel.

On the latest cheap Poulan I ported I intentionally used a carb where the choke won't pull off when I open the throttle. Also used the later flywheel with more fan fins. I'm hoping it will be easier to get going again when it vapor locks, which it will.

I find the saw may fire on full choke but needs to actually run there to recover. If the choke kicks off it will stall again.

 

[MountainHigh]

So if it is vapour lock, I'm wondering if the new 562 top cover with it's newly designed open air port next to the cylinder will help? The fact it is now there suggests they are trying to cool things down better.

 

[Chris-PA]

So if it is vapour lock, I'm wondering if the new 562 top cover with it's newly designed open air port next to the cylinder will help? The fact it is now there suggests they are trying to cool things down better.

Maybe, but I'm skeptical. Mostly I think the problem is heat soak once you shut it off and the air flow stops. So I try to let it idle a bit before shutting it down. Anyway, unless the cooling while running is really inadequate then it's hard to see how that would help much, but maybe.

 

[Andyshine77]

Well they did add an extra vent in the top cover.

 

[CrufflerJJ]

~ After a few to ten minutes. I pick up warm 562 and use Hot start (choke UP then Down, which always worked fine before) with decomp button pressed in, and pull till the freaking cows come home - Nadda!

Use the hot start setting as you specified, but DO NOT push in the decomp button. Doing it that way, my 562XP starts back up with a single pull most of the time. That decomp button makes a huge difference with warm/hot restarts.

 

[MountainHigh]

Use the hot start setting as you specified, but DO NOT push in the decomp button. Doing it that way, my 562XP starts back up with a single pull most of the time. That decomp button makes a huge difference with warm/hot restarts.

Seems very odd the decomp button makes any difference at all, but I appreciate the suggestion and will try it out.

 

[Andyshine77]

Seems very odd the decomp button makes any difference at all, but I appreciate the suggestion and will try it out.

It reduce compression too much. The 550 has a redesigned combustion chamber, my guess is to improve compression a little, and it looks like the newest 562's may have a new cylinder as well.

 

[c5rulz]

Well they did add an extra vent in the top cover.

View attachment 496462

With the position of that vent, it would appear to be designed to let heat out when the saw is off.

 

[chainsaw wizard]

I've got a 562XP which unfortunately doesn't have a warranty. It starts cold beautifully, it restarts hot just fine (slide up to choke on, slide back down to fast idle engaged). After cutting for a while it gets more and more likely that it won't restart, particularly if left for 10 minutes or so, and almost definitely won't start if I leave it for 20 minutes. Once I see that I have a problem, if I leave it alone for a while (never timed it) it comes good again, so it seems to get into some kind of temperature related state. Also, I've not sat down with a stop watch (yet), so my times may be a bit off.

Things that may be relevant..

When it's in this state the air purge bulb doesn't "work", pushing in feels too easy and it never pulls fuel through. I can tell when it's good to go again because I'll come back and the bulb will suddenly be almost completely full and it'll start just fine (though it does idle a bit funny after these restarts, sometimes dies but starts right back up again, but after the first cut it's back to normal).

Oh, the important bit, when it's in this state I can't seem to get it started at all. Sometimes I can get a little rumble for a few seconds but usually nothing.

When you open the fuel cap air there's some positive pressure in the tank. Opening & closing the tank doesn't change anything (I've never had first hand experience with vapour lock, but it seemed like it was worth a test). The weather here's around 15-25C, nothing extreme.

The carburettor is an EL46, no hesitation off idle issues, and from a cold start it's fantastic. Sometimes after a warm restart (or one that's just on the edge of getting it going again) it can be a little reluctant to idle until it gets back up to temperature, and sometimes needs a few blips to get itself sorted out. When I say warm here, if it's running, I stop it to roll a few logs and start it again within a minute or two I'll call it hot, and those starts are fine. Warm would be maybe up to 10 minutes or so, and much more than that I'd be expecting it to get stuck again.

I have been having an ongoing issue with really fine dust getting past the filter. I think it's the crappy bark on these gum trees. I'm pretty confident I'm on top of the problem now that I've got some spray oil for the filter now, and have started running a small line of grease around the outside edge of the filter holder in case it's getting around the filter (I found a thread about that). I took the carburettor off last night and cleaned out some obvious fine dust (that I really hope hasn't done damage to the cylinder), I haven't tried it again yet.

I did come across a comment (that I can't find now), where someone described exactly this problem as one of a few known issues that Husqvarna were working on, but the author had not been active on that forum for quite some time. He mentioned in the brief comment that it was related to a check valve in the carburettor, I think he said impulse line but I can't find the comment right now.

It's possible that this has always happened with this saw, I'm a home owner with a nice saw because I knew eventually I'd get around to the job I'm doing now. Previously I'd only really do 1 tree at a time, or take enough of a break between cutting to not notice. We finally got around to having 20 trees dropped more safely than I could do them, so now it's clean-up time and I'm out there any time I can get away from work.

Possibly related, it does sometimes (not often) seem to get itself flooded on a restart even though I'm not using the choke (just fast idle). When this happens I can get it started as you'd usually start this saw while flooded (throttle + knee + lots of careful). I think this is unrelated but just thought I'd throw it in here.

Can anyone give me some ideas of where to go from here?

 

[chainsaw wizard]

we had two 562xp's come through our shop with a similar issue..try to put an up-dated breather and plug...part # 513751501 and 537051801..this worked on both saws..Husqvarna tech support can walk you through this..