Husqvarna 372 Not starting - suspected fuel problem

[Castn'Blast]

Happy to be posting for the first time on this site. Long time lurker, first time poster.

I bought a brand new Husqvarna 372 X-Torq in 2021 and have probably cut around 8 chords of wood with it so far. The saw has been my primary for the entire tree processing workflow: felling, limbing, and bucking. I absolutely baby this thing as firewood collecting has become something of a hobby - something fun to do to get outside on the weekends. I clean it after ever time out, and only run Husqvarna/Stihl brand gas through it. Furthermore - I don't keep gas in it for long and make sure to run it until it's out of fuel for storage.

Leading up to this moment, this thing has been one of the easiest starting saws that I have ever run. Switch on, choke out, push decomp in, three pulls produces combustion, choke back in, one more pull and the saw is running. With that said, last weekend I went out to collect some more wood and followed the standard starting procedure and was surprised to find that I couldn't get this thing to start. Figured that I must have (for the first time) flooded it and let it set for 24 hours. Came back the next day and had the same issue, could not get the thing to start (or even kick).

So thus begins the order of problem solving operations. Here's what I have done so far.
1. Took the spark-plug out and grounded it to the case - saw spark
2. Poured about 1 teaspoon (for volumes, I think in metric so .5mL) of gas down into the cylinder and couldn't get combustion
3. Checked the gas tank and the fuel line/filter don't seem to be pinched, but it is slightly twisted. I can elaborate on this if necessary.
4. Observed that after pulling and pulling (with the choke in/out) I never smelled fuel from the saw.

I'm hoping that there's a simple fix here and that you seasoned folks may have a solution.

Thanks for your help guys, I really appreciate it.

V/R
Castn'Blast

 

[Backstage]

If you suspect a fuel problem, eliminate the variable. get a little can of canned gas and retry.

If you’re thinking fuel delivery, pop open the carb and check it out. You may have debris ingress blocking. Another possibility is the fuel or impulse lines are worn and cracked.

 

[Big_Eddy]

You say you have spark. That’s a good start. Take the plug back out and dry/clean it off well or better still replace it, then try the next step. (I’ve seen several cases where a marginal plug will show spark outside the engine, but not within). Oh - and pull that decomp button back out and don’t touch it for the rest of the testing. If you are having any issues starting, you want all the compression available.

Don’t put fuel in the cylinder. It is too easy to wet the plug. Instead remove the air filter and dribble a small amount of mix into the carb. You should get a pop or two or a few seconds running. If you do but it won’t keep running, then the carb, impulse or fuel lines are suspect. If no pops at all, then on to compression.
Without a compression gauge, not easy to tell, but If the saw pulls over super easy you don’t have compression. Or take the plug out and put your thumb over the hole while you pull the cord. Does it force your thumb off? if not, then poor compression. Or use or borrow a compression gauge and know for sure. You are looking for 150psi or more. Under 100 is bad. Again all with the decomp button left alone I.e.out.

If you get this far and are still not running, its time to go back and look at the spark in more detail. Spark strength and timing. But you indicate it ran well before being put away, so I am not suspecting a sheared key or coil gap problem - yet.

 

[ken morgan]

pull the plug flip it upside down and crank several times it to ensure the case is has not got liquid fuel in it after pouring a teaspoon into it.

If you put too much fuel in it will wash the oil off of the walls drastically lowering your compression.

After doing this change the plug and try with fresh gas.

Seeing a spark in the open with no compression is totally different from a spark in the chamber when under compression.

good luck.

 

[huskihl]

I’d remove the muffler and see if there’s any scoring on the piston

 

[ken morgan]

I’d remove the muffler and see if there’s any scoring on the piston

Yep this too. easy things first.

 

[bwalker]

Spark, fuel, compression. It will start with these three things.
Pick the saw up by the starter cord and see if the saw will hang without falling to the ground. If it holds you have compression. If not pull the muffler.
If no scoring is present throw a new plug in it and give it a try.

 

[bwalker]

pull the plug flip it upside down and crank several times it to ensure the case is has not got liquid fuel in it after pouring a teaspoon into it.

If you put too much fuel in it will wash the oil off of the walls drastically lowering your compression.

After doing this change the plug and try with fresh gas.

Seeing a spark in the open with no compression is totally different from a spark in the chamber when under compression.

good luck.

No need to be paranoid about a little fuel in the cylinder. When a two stroke is cold litteraly every internal part is coated with raw gasoline in a liquid state. Only after the engine is warm will the fuel change state to a gas where after it can be combusted. It's for these reasons that two strokes smoke alot when cold and require alot of extra fuel to start via the choke.

 

[ken morgan]

No need to be paranoid about a little fuel in the cylinder. When a two stroke is cold litteraly every internal part is coated with raw gasoline in a liquid state. Only after the engine is warm will the fuel change state to a gas where after it can be combusted. It's for these reasons that two strokes smoke alot when cold and require alot of extra fuel to start via the choke.

fair enough, but when I had that weak coil issue on frankensaw 6 years ago the first thing everyone told me was pull the plug, flip it upside down so that the sparkplug hole was facing down and crank it repeatedly to insure that the crankcase did not have a lot of fuel in it... then new plug and test. it worked then, sure it will work now.

 

[bwalker]

fair enough, but when I had that weak coil issue on frankensaw 6 years ago the first thing everyone told me was pull the plug, flip it upside down so that the sparkplug hole was facing down and crank it repeatedly to insure that the crankcase did not have a lot of fuel in it... then new plug and test. it worked then, sure it will work now.

Holding the throttle wide open with the choke off accomplishes the same thing.

 

[1hp]

spark arrestor screen dirty?

 

[Castn'Blast]

Hey all,

Thanks for all of your input, I really appreciate it. I finally got the saw running today. The culprit was a dry diaphragm in the carb. I took a little fuel and put it in the air intake and a few pulls later she was running.

It was an extremely hot and dry day when the problem first occurred. Also, my saw was completely empty of fuel and had been sitting in the back of a hot truck as well. A little fuel to wet the diaphragm was all it took.

Again, thanks for your input and I hope this helps someone else!

Castn'Blast

 

[Old2stroke]

Holding the throttle wide open with the choke off accomplishes the same thing.

Only if you want to do a LOT of pulling and the crankcase isn't full of fuel.

 

[bwalker]

Only if you want to do a LOT of pulling and the crankcase isn't full of fuel.

Nope, only takes a few pulls.

 

[Husky77]

if your using husqvarna/stihl fuel why do you empty the tank to store the saw? this fuel is not like petrol it can be left in. Anyway if your not getting fuel through I would test your fuel pipe for leaks but another think to watch is a stuck fuel meter needle (if thats what its called) it often happens when saws are stored dry and a tiny bit of oxidation on that part will give you hours of grief. Its a simple fix, your using good fuel so leave it in and that will never happen. good luck

 

[The Shooters Apprentice]

Personally I never run my saws out of fuel. I find if I run them dry and then let them sit awhile they are very difficult to get running again.

 

[Castn'Blast]

if your using husqvarna/stihl fuel why do you empty the tank to store the saw? this fuel is not like petrol it can be left in. Anyway if your not getting fuel through I would test your fuel pipe for leaks but another think to watch is a stuck fuel meter needle (if thats what its called) it often happens when saws are stored dry and a tiny bit of oxidation on that part will give you hours of grief. Its a simple fix, your using good fuel so leave it in and that will never happen. good luck

I guess that it's really just an old habit. I have my A sawyer cert from the FS and that's what they taught us to do. I suppose that I was always worried that it could cause fuel lines and other rubber/plastic parts to become brittle (but that's just my hunch). I'll start leaving fuel in my saws. My dad has done it for years and has had no problem. Thanks for your response!

 

[Castn'Blast]

Personally I never run my saws out of fuel. I find if I run them dry and then let them sit awhile they are very difficult to get running again.

Do you run your saws often? I.e. like at least once a month? Or are you letting them sit for prologued periods of time? Nonetheless, I think that you're probably right. Stable fuel is fine to be left in saws for the 4 months out of the year that we might not be running them. My only concern is that fuel lines, etc. may become brittle with prolonged exposure to a solvent like petrol. Thanks for your response!