Stihl 261. Starts when cold. Fails to restart when hot.

[Bfitzgerald3]

Ran the saw for quite awhile yesterday... 3/4 tank, some down time here and ther to move branches around. Then it woldnt start. Set it aside, went back, started right up. Ran for awhile, again with short stops, and the problem came back. This morning, cut for maybe five minutes with the usual intermittancy, same ole same ole.

Ive run maybe five tanks of gas through it since purchase. Seems like things shouldnt be breaking.

Airfilter....nice n clean. No gunk on the cooling fins..seems pretty clean.

Readjusted carb to factory settings.

I do hear a sucking sound when opening the gas tank...not sure how to check th vent, but think it may be an issue.

Other ideas?

Thanks!

 

[yomax4]

If you remove the air cleaner cover you should see the vent hose on the bottom left right above the gas cap but under the cover. Mine pinched off and I had the same issue. I found a smaller harder plastic hose that I slipped inside the regular one. Worked for 10 years.

 

[s219]

What is your warm start procedure? You are not choking the saw when warm, correct?

 

[s219]

Also, the fuel tank should be at a slight negative pressure when running so you should hear sucking inward when opening the cap. The vent is only there to relieve over-pressure.

 

[Bfitzgerald3]

Start procedure....first start, choke, three pulls, relieve choke, pull...usually takes off on first or second unchoked pll. When hot, i try with no choke three, maybe four times. Until recently, this worked. Now, I then choke it up, pull a few, relieve choke, will often start, but not keep running.

I know i said i heard sucking, but honestly, it cold be a blowing. Seems like theyd sound roughly the same.

Could this be vapor lock?

Tomorrow, i'll take a peek a the vent and see if i can distinguish between sucking and blowing sounds.

 

[s219]

And the gas is OK, not old or anything? Saw hasn't been stored with ethanol gas in it for more than a couple weeks?

A hot saw with warm carb can alter things a little bit. Shouldn't impact you unless there is something wrong and your carb settings are a little marginal. Then it can be enough to have an effect.

If there is a pressure issue in the tank, you can crack the cap before you try to start the saw warm, and see if that eliminates the problem -- it's a simple test.

BTW, I said the wrong thing in the previous post, the vent is there to relieve suction, not over pressure! Must have been past my bed time. There can be a little suction when you crack the cap, but if it's a great big hickie sound, then I suspect maybe the vent isn't working.

 

[s219]

The other thing to check would be the coil -- they can crap out when they get hot, and cause issues. I guess it would be good to determine if this is a fuel issue or a spark issue.

 

[Bfitzgerald3]

Unfortunately, gas has sat in the saw for months. Worried about ethanol issues. Bought new gas today, but didnt have the chance to put it in and give her a run. Tomorrow morning,i'll be clearing some more dead fall...hopefully new gas wll make the difference. Ethanol...crap.

Anone know where a source of non alcoholic gas may be? Someone suggested a marina.

 

[s219]

Well, your carb might be buggered up then -- seen it many times. Ethanol gas is a real PITA for chainsaws. I never let it sit in mine more than 2 weeks. Months could be very bad. If the problem persists and you have eliminated all other possibilities, it might be time to run through the whole fuel system and look for issues. Might need a carb kit.

You can google for non-ethanol gas to bring up a few websites that track availability. Marinas often have it, but the octane is probably going to be 87.

 

[yelbike]

Next time it won't warm start, crack the gas cap to relieve any possible lock and than try again. At least you'll know the problem is or isn't the cap or vent. Good luck.