338 XPT won't idle

[Toyboy]

Doing this from a distance.
Friend of mine has the above saw and replaced carb. He's telling me he can't get it to idle (running fast). I told him to readjust L (open) and idle screw then get back with me. To me it sounds like L is tuned lean. Am I missing anything ??

 

[RedneckChainsawRepair]

If just not carb tune and old mix.

Worst case could be a impulse line, intake boot ripped, carb rebuild time. Seen them all on these.

 

[Toyboy]

Well, he still can't get it totally correct so he's selling it to me. New carb, chain and gas/oil caps. Maybe a couple more smalls.
I don't need it but couldn't argue price.

 

[Toyboy]

Well I picked the saw up today and spent several hours trying to solve this problem. It'll start, run, and rev good but getting it to consistently idle has eluded me. It'll idle and then it won't. Just about the time you think finally, it'll die again. It doesn't seem to be sensitive to carb adjustments on L even though it's a new Zama.
I thought this would be somewhat easy tune, but instead it's getting to be just the opposite. Had the carb off twice looking for something.....anything that would give me a direction. I'm stumped.
Suggestions....

 

[EchoRomeoCharlie]

Air leak. You need to do a pressure test.

If it's not the crank seals, it's an intake boot or something. It's sucking air from somewhere other than the carb.

 

[Toyboy]

ID tag has 334T ???? By looking at the DOM do you think it's worth putting more $$ in to fix whatever it needs ??

 

[EchoRomeoCharlie]

Depends on where it's leaking. If it's just an intake boot...probably worth it. If it's crank seals, and you can do the work yourself....and you really like/want the saw....maybe worth it.

If you have to have a shop fix it, probably not worth it.

 

[Franny K]

View attachment 1168994
ID tag has 334T ???? By looking at the DOM do you think it's worth putting more $$ in to fix whatever it needs ??

I would say a 338xpt new edition would be the best choice on that platform. Not sure what is better or worse vs the 334 here. The anti vibe is quite impressive especially the one at the rear. The air filter is the real problem, gets dirty and eventually you damage it. There is the white and the black solid parts ones for mine. It is supposed to have an automatic compression release which for me must be working.

 

[RedneckChainsawRepair]

I really liked the 338's and all they needed was a muffler mod. To me they had the best balance etc using. Even over my 200T.

I just didnt care for how the 338's were built though. But it worked.

Ended up selling all 3 when the 540 came out. Boy that was a kick in the nads. Wished I would have kept one of the 338's.

There is updated air filter used on them. Get that and check the boot and seals for a leak.

 

[Toyboy]

It appears the boot and impulse line is fine but looking like I need a new coil. That couldn't be causing all the problems could it ??

 

[EchoRomeoCharlie]

I've never had an inconsistent idle problem be a coil issue. That's not to say it's impossible...but almost always what you're describing is caused by an air leak.
If you can't or don't have the equipment to run a pressure test on the saw, you can do the following:

Run the saw, spray some brake cleaner by the crank seals. If idle changes when you spray it, you have bad crank seals. You can also spray by the intake boot. Same thing. If idle changes, wherever you sprayed is the air leak. Obviously you don't want to do this a lot as the brake cleaner will remove all the oil from inside the saw...but it's a cheap way to check for air leaks.

 

[Toyboy]

Your right, I do not have the capacity to do a pressure test. I will use your brake cleaner test when it's in a condition to run. I've not been able to find crank seal in part list or even part # for them. Could it be they're using sealed bearings instead ?
I've been looking at coils on eBay and was wondering if anyone has used the aftermarket coils? If so, what brand/seller to use OR, has anyone on here have a good one they will part with.
Husky # 54404 70-01

 

[Chevboy0167]

https://www.partstree.com/models/334-t-husqvarna-chainsaw-sn-20040100001-20051000000/crankshaft-3/