Problem with 372xp x-torq shutting off at WOT

[stihl 440]

I've been running this new Husky 372xp x-torq for 1 1/2-2 months now at work and it ran flawlessly until a couple weeks ago it developed a problem shutting off when in the cut or out of the cut at WOT. But it only does it when the saw gets up to temp..i thaught it might be too lean but it de-tuned it clear down to 12,500rpm and it still does it...it was previously running 13,400rpm. No matter how the high,low or idle screws are set it still does it. And when it shuts off its not running out of fuel its just like you hit the kill switch and you cant bubble the throttle to get it back. I had it to the shop once and we put a new fuel filter, stop switch, and tank vent hose on it since i thaught since it only did it once the saw was hot, i thaught it might be vapor locking. I also thaught it might have had water in the tank so i dumped the tank and put brand new fresh mix in it and we still have the problem. But after all that still no go...it sounds like an ignition problem, or maybe something else that im not seeing..but after it shuts off it restarts in one or two pulls...it also is a freaquent problem..sometimes every minute..which is no good when your half way through a tree getting ready to turn it loose. Any of you guys know what this could be?

 

[funky sawman]

Sounds like an ignition module failure, or a wore threw (grounding) kill switch wire

 

[stihl 440]

It also backfires sometimes when you go to start it again when its warm...if that may help..

 

[hamish]

Recheck the tank vent, if the tank vent hose was replaced why? its just a hose lets air in and air out, its the actual vent that does the work and is a easy test with a vac/pressure gauge, as is checking the stop switch with a multi meter, fuel filter is quick visual inspection and confirmation with the vaccum gauge once again

Coil failure does happen but its not very common anymore.

You may want to re-confirm with your shop, and see if they re-bore chainsaw cylinders for the first oversize piston ot not.

 

[watsonr]

Coil problem, I have saw doing the same thing, 7900 Dolmar. New coil fixed it.

 

[zogger]

It also backfires sometimes when you go to start it again when its warm...if that may help..

Well, a true backfire (through the intake) is ignition firing too soon, it is advanced somehow beyond where it wants to run correctly. So ignition woes with a solid state system like that would indicate a coil problem most likely, or somehow the flywheel moved on the crank? If it was the flywheel though it would be all the time, and you said only when hot/warmed up, so that again narrows it down to a coil problem, and the shop should have bingoed to that right off the bat, given your initial symptoms. I mean, it was getting enough gas to run at wot, and that wasn't likely to change unless you were cutting in death valley at high noon in July. But it poof shut off. No sparky/bad sparky/wrong sparky/

Especially after they changed the other stuff and looked at it and *most likely* found nothing wrong with it.

 

[stihl 440]

Well, a true backfire (through the intake) is ignition firing too soon, it is advanced somehow beyond where it wants to run correctly. So ignition woes with a solid state system like that would indicate a coil problem most likely, or somehow the flywheel moved on the crank? If it was the flywheel though it would be all the time, and you said only when hot/warmed up, so that again narrows it down to a coil problem, and the shop should have bingoed to that right off the bat, given your initial symptoms. I mean, it was getting enough gas to run at wot, and that wasn't likely to change unless you were cutting in death valley at high noon in July. But it poof shut off. No sparky/bad sparky/wrong sparky/

Especially after they changed the other stuff and looked at it and *most likely* found nothing wrong with it.

I dont think the flywheel sheared the key or spun on the crank to advance the timing..as they bought two of these saws at the same time and the other one does it some times too..i think maybe husky did advance the timing on the x-torq models over the older style ones like i own, as they never backfire..to be honest this is the only husky that has give me trouble. Our husky shop that we got close here is not that good imo..they just became a husky dealer about a year ago..and the owner doesnt have a saw mechanic in there he does the work himself and he never worked on saws before..so pretty much he dont know too much if you know what i mean. But the thing is still under warranty so he needs to fix it...i told him to check the whole ignition system..wires and all..so we'll see if he gets it fixed. If it was up to me i would just check the wires and put a non-limit coil on it and be done with it...not have to worry about it and run it. I will give the x-torq credit..stock to stock a older 372 wont touch it...they are definetly stronger.

 

[stihl 440]

Recheck the tank vent, if the tank vent hose was replaced why? its just a hose lets air in and air out, its the actual vent that does the work and is a easy test with a vac/pressure gauge, as is checking the stop switch with a multi meter, fuel filter is quick visual inspection and confirmation with the vaccum gauge once again

Coil failure does happen but its not very common anymore.

You may want to re-confirm with your shop, and see if they re-bore chainsaw cylinders for the first oversize piston ot not.

The saw isnt blown up or scored..i pulled the muffler already and checked.

 

[Jacob J.]

Sounds like an ignition module failure, or a wore threw (grounding) kill switch wire

Yep. When those newer blue coils fail, they "clip out" at high speed or full throttle. Then they backfire when you try to re-start.

I've junked two of the newer blue coils already.

 

[stihl 440]

Yep. When those newer blue coils fail, they "clip out" at high speed or full throttle. Then they backfire when you try to re-start.

I've junked two of the newer blue coils already.

That sounds exactly like my problem right there..

 

[fearofpavement]

almost for sure ignition related as opposed to fuel. Change the plug if you haven't (cheap and easy) but I think the coil is the culprit too.

 

[stihl 440]

They sent this saw to the shop first and the dealer said he couldnt find anything wrong with it and de-tuned it to 12,500rpm and said thats where it should run..the way i took it he was insulting my tuning...i told him these are rev-limited to 13,500rpm and they should do 13,400-14,000 with a non-limit coil all day everyday still 4 stroking out of the cut. He told me that would burn a hole in the piston..i said expain the 25+ 371,372's that i have built and or worked on and have never been to the shop since. He said he didnt know..:msp_razz: Anyway..he sent it back and it shut off on me 10 or more times later that day...needless to say i was NOT happy. So back to the shop it went and i said now, put a coil in it like i told him it was in the first place..if the thing wasnt under warranty i would have done it myself. He put a non-limit black coil in it..next day..it run all day like a top. So pretty much any other 372xp X-torq's that have this issue, fix it with a black coil and be done with it. I had it tuned at 13,600rpm and it runs like a top all day long.