Husqvarna 440 xtorq won't stay running - help please

[jstroder]

This is a fairly new saw with little use. The saw will run but after about 30 seconds it starts running very rough and then dies. I replaced the carburetor, fuel lines, and primer bulb but still runs like crap. It seems like an air leak, does anybody have any ideas??

 

[s sidewall]

Check fuel tank vent, spark plug?

Steve, Samsung On5 using Tapatalk

 

[ncfarmboy]

Do a pressure/vac test sounds like a vacuum leak. Possible areas are crank seals, Intake manifold were it bolts to cyl. and transfer covers. I have a 450 does the same thing 3new carbs 3 coils passes press/vac test ($45.00 block off plate for blocking off carb). Pressure tested fuel lines, new crank seals, anaerobic sealant on everything that bolts on. Still haven't figured it out.
Shep

 

[s sidewall]

Spark screen for carbon build up?

Steve, Samsung On5 using Tapatalk

 

[Westboastfaller]

Here we go again
Yeah I have some ideas.
buy two saws the same.
At this point buy more parts.
That should do it
Next question please. J/k

 

[Westboastfaller]

This is a fairly new saw with little use. The saw will run but after about 30 seconds it starts running very rough and then dies. I replaced the carburetor, fuel lines, and primer bulb but still runs like crap. It seems like an air leak, does anybody have any ideas??

What would possess you to buy all those things? You seem to believe it's fuel/fuel-air related? Maybe so but your post lacks clarity don't you think? Sounds like piston/compression issue. Got hot or straight gassed if I was allowed one guess.
Its just a guessing game. You have got to either put a little more time into writing or put up a video.
The alternative to that is buy more parts and doing unnecessary labour in the wrong area. Fair?

 

[s sidewall]

Sounds like the last saw we worked on don't it, post a like to it please.

Steve, Samsung On5 using Tapatalk

 

[hangfirew8]

This is a fairly new saw with little use. The saw will run but after about 30 seconds it starts running very rough and then dies. I replaced the carburetor, fuel lines, and primer bulb but still runs like crap. It seems like an air leak, does anybody have any ideas??

Test the compression. Pull the muffler and see if it is clear or clogged or loaded with fuel. Take a look at the Piston and cylinder and see if they are scored. How much carbon inside? Replace the spark plug, its cheap. Inspect the intake for cracks and gaps.

-HF

 

[Westboastfaller]

Sounds like the last saw we worked on don't it, post a like to it please.

Steve, Samsung On5 using Tapatalk

hard to say. I hate when people use the word "run" without a description. Is that to mean "idle" or runs perfectly in all areas for 30 sec then shakes and stops. Then I would lean towards top end or clutch.
He has written no description to support why he thinks what he thinks.
Don't think he would have vent issue in 30 sec unless he was cutting hard then it's possible. the chain will race up then cough out unless you open the fuel cap. One of the easiest things to check.

 

[hangfirew8]

Jstroder you know if u have a vent issue if you remove the cap immediately after it stalls, and there's a vacuum noise of air rushing in.

I have a 435 that has had no problems, same saw just lower compression. But I also have a small stable of errants that have or had just about every malady known.
-HF

 

[jstroder]

The spark screen is clear, I installed a new spark plug, I removed the muffler and didn't see any scoring on the piston. The L and H screws are 1 1/2 turns out each. I didn't do a pressure/vac test because this is practically a new saw and I didn't figure the crank seals or intake manifold had blown out already, also I just haven't had the time to do it. I was hoping maybe someone else had the same saw with a similar issue and could offer a solution. Below is a video of the saw running and then stalling out. It does this every time.

 

[Ozhoo]

I'm late to the party... set the carb to 2 on the low side and 2 1/2 on the high, give her a go.

 

[SierraMtns]

I'm late to the party... set the carb to 2 on the low side and 2 1/2 on the high, give her a go.

What he said...

Should like it needs more fuel.

 

[Westboastfaller]

Yeah it's definitely appears it's not regulating air fuel. It doesn't appear that it is in the low jet ajudgments to me... If all is working properly then the carb would set it to a certain behavioral mode but it goes from a lean "race" to coughing out (starve) at idle. Any personal experience with a leak with similar symptoms where the saw won't rev up fully would be from a loose cylinder and separated at the base.
Manifold leaks may run erratic cold or from movement but generally go to a steady race when hot.

If you handed the saw to me I would make sure the cylinder is down and in tact. look at the case also quickly.
Then I would get I little squirt bottle
and fire it up then sqirt and hit the trigger. If it runs up good then a would turn back and close out your problem. Did you check impulse port was clear when you did the carb? It very much resembles an inadequate
impule. if it's not a mass lower leak
Don't know the model at all but those are the two things that fit the best. I'm making the assumption that the new carb is perfect at this time.
but never to be ruled out.

 

[ncfarmboy]

Do a pressure/vac test sounds like a vacuum leak. Possible areas are crank seals, Intake manifold were it bolts to cyl. and transfer covers. I have a 450 does the same thing 3new carbs 3 coils passes press/vac test ($45.00 block off plate for blocking off carb). Pressure tested fuel lines, new crank seals, anaerobic sealant on everything that bolts on. Still haven't figured it out.
Shep

Put another new coil on it problem solved.
Shep

 

[jstroder]

I finally got around to working on this again. Did pressure/vac test and sprayed everything with soapy water, didn't see any bubbles anywhere. Pressure/vac held for several minutes as it should.
The only thing I could think that was causing my issue was maybe the carb was not seating on the intake manifold correctly. I reassembled everything and very carefully re-installed the carb. I cranked it up and ran pretty good. I tuned the carb a little more and seems to idle and run as it should now.