044 stumbles at idle....

[Davey83]

hi all, I have a friends stihl 044 at the moment and it's giving me grief! Usually I will figure out 90% of small engine issues but this one......
so I recently gave it a new piston and ring as it was slightly scored and I cleaned up the original cylinder, so I know the compression is great.
After I rebuilt it I ran one tank through it and noticed no running issues, I tuned it slightly fat as I always do for engine longevity.
Anyways he claims he used it once and said it ran great, and now the second time he went to use it it kept stalling out when he put the saw down, since running the saw myself it runs great at wide open throttle but when you let it idle it stumbles and gets worse and worse until it stalls out then it's very hard to start.
I removed carb and gave it a new diafram kit, new needle, changed fuel filter, and some fresh fuel, (just incase his fuel was bad.
After all that, it's still the same.
Also I re inspected the piston all ok.
I've checked fuel line and impulse hose, ok.
I'm now starting to think crank seals
But I thought bad crank seals make the saw lean out and idle up not down.
Any advice would be great. !

 

[jb-chainsaws]

Can you not re-tune it and see if it holds the tune? Could still be a carb issue, but I'm Interested to hear what others suggest

 

[backhoelover]

need to do a pressure and vac tester.

 

[backhoelover]

depends on the size of the leak. ive seen seal looks so bad that the carb fuel pumps couldnt pull fuel from the gas tank. i haver also seen where the seal would only leak above 6000 rpms. also make sure that the tank vent is good

 

[merc_man]

Pressure vac test the fuel system and motor as mentioned above.

Sent from my SM-J320W8 using Tapatalk

 

[SixGun]

If you don't have the tools for vac/pressure test, just go ahead and do the crank seals.
They are pretty cheap and not too hard to do. Get a couple extras if its your first time.
Also check the intake boot for a rip.

 

[huskyboy]

Lean out the L just till the idle barely starts to climb and then leave it. Mine had the same issue if it was tuned too fat on L. The fuel pools in the intake on those saws and a correctly tuned L screw migitates that.

 

[Davey83]

thanks for the replies, at this point I removed impulse hose and intake boot and closely inspected them, there ok and free of any splits plus the clamp was tight. I have orderd a set of crank seals and going to try that, I do not have a pressure/vac tester unfortunately I should invest in one though.
ill keep updating the progress

 

[Davey83]

I just wanted to give an update on this saw,
so I completely removed fuel tank and thoroughly checked fuel hose and intake boot, they are perfect, the tank vet breaths to.
I then replaced crank seals and checked crank movement while I was at it, there was no movement and bearings spin smoothly,
also the coil has correct air gap and the key for the flywheel is not sheared
I also pulled carb back apart and made sure all my diaframs were fitted correctly and that the metering lever was at correct height
all was ok.
so I'm very confused as to why its still runs good at WOT but when you let it idle it has an uneven idle that stumbles and slowly gets worse than stalls out
its almost like its flooding itself, I'm thinking of replacing the carb but I would not like to waste more money.
I should also note I did a base gasket delete when I rebuilt saw but I don't think this would have anything to do with it......would it

 

[Davey83]

one other thing,
I was looking online at carbs for the 044 and including HLsupply website and I noticed they have a universal carb that will bolt onto a 044 and 046 but when I compared the carb off this 044 to the 046 carb it has a smaller throat size ?

 

[Davey83]

hi there, just an update if anyone is interested, i have fixed the issue with this saw!! and as mentioned above i defiantly need to invest in a pressure/vac tester so as it turns out i had an air leak coming from the cylinder base, you see i done a base gasket delete to this saw and it happened to blow out some sealant as there is a small cavity on the sealing surface of the cylinder where i assume an impulse fitting may be used on some models but it created a very small sealing surface for the sealant to work, as ive done at least 30 base gasket deletes in the past trouble free i did not consider an air leak at all.
a good learning curve for sure.
the piston on the intake side has had a bit of wear unfortunately due to this air leak but no scoring. i will reuse it. and ive now fitted a base gasket to bring it back to stock.

 

[Davey83]

hi there, just an update if anyone is interested, i have fixed the issue with this saw!! and as mentioned above i defiantly need to invest in a pressure/vac tester so as it turns out i had an air leak coming from the cylinder base, you see i done a base gasket delete to this saw and it happened to blow out some sealant as there is a small cavity on the sealing surface of the cylinder where i assume an impulse fitting may be used on some models but it created a very small sealing surface for the sealant to work, as ive done at least 30 base gasket deletes in the past trouble free i did not consider an air leak at all.
a good learning curve for sure.
the piston on the intake side has had a bit of wear unfortunately due to this air leak but no scoring. i will reuse it. and ive now fitted a base gasket to bring it back to stock.

 

[huskyboy]

hi there, just an update if anyone is interested, i have fixed the issue with this saw!! and as mentioned above i defiantly need to invest in a pressure/vac tester so as it turns out i had an air leak coming from the cylinder base, you see i done a base gasket delete to this saw and it happened to blow out some sealant as there is a small cavity on the sealing surface of the cylinder where i assume an impulse fitting may be used on some models but it created a very small sealing surface for the sealant to work, as ive done at least 30 base gasket deletes in the past trouble free i did not consider an air leak at all.
a good learning curve for sure.
the piston on the intake side has had a bit of wear unfortunately due to this air leak but no scoring. i will reuse it. and ive now fitted a base gasket to bring it back to stock.

Most saws get wear on intake skirt even after low hours.

 

[Adirondackstihl]

You ever figured out why it cooked the first time?

 

[Davey83]

You ever figured out why it cooked the first time?

It never was cooked so to speak but it was the original piston and had quite a bit of wear as this is a high hour saw, so it was more a case of giving it a freshen up.

 

[Adirondackstihl]

I'm thinking you just haven't hit the sweet spot combination of "L" & "LA"

Sounds like it's too rich on L
Lean it out some and back the idle out some to equalize the idle RPM.
Which should be approx 2800

 

[Canadian farm boy]

I'm thinking you just haven't hit the sweet spot combination of "L" & "LA"

Sounds like it's too rich on L
Lean it out some and back the idle out some to equalize the idle RPM.
Which should be approx 2800

Agreed. It sure sounds like its to fat on the L setting.