Author Topic: 026 stihl won't stay running (Read 27238 times)

wannabeonetoo · « **on:** October 24, 2008, 08:57:09 AM »

Hi folks;
Got a question for you stihl experts out there. My buddy has a stihl 026 which he went to fire-up this week and couldn't keep it running.
I was with him yesterday and tried again to no avail. He put a new carb kit in,adjusted it to the specs in the manual,new gas. Set the choke, 2 pulls and we had ignition !!! Went to give it a little throttle ...BLAHHH..it died. This would go on as long as we were willing to play the game.We even tried tweeking the jets as it was idling , no go .
So...what are we up against ?? and to do ??
This saw is in good condition,never abused,not many hours on it , always had the correct gas/oil mix.I don' think he wants to pay the $70/hr the dealer charges between the two of us we're handy enough to tackle most anything.
Thanks for any help given
Steve

ladylake · « **Reply #1 on:** October 24, 2008, 06:39:18 PM »

Most likely the carb is still gunked up, gas goes bad fast these days. Use Stabil and try to get gas without ethonal. I just went through the same thing with a Husky 55, hit the throttle and it dies. On my third atempt at cleaning the carb it finally works good. I took the needle valve out and all of the plastic and rubber and soaked it in acetone for 10 minutes, I don't know if that helped but it works good now. Try opening both jets up 1-1/2 turns 1st, if that doesn't make it run richer it would be the carb. Steve

sawcollector · « **Reply #2 on:** October 24, 2008, 10:59:42 PM »

I agree with ladylake that the carb may be gunked up but lets pretend we are a fuel molecule and we want to find our way to the combustion chamber.
First the fuel filter must be clear. No gunk in the tank. So the saw has been sitting for 2 years so all the old fuel has turned to varnish, then you just put E10 in it and dissolved all the gunk in the bottom of the tank and now the filter is clogged up. So let's make sure the filter is clear and not plugged up. Pop it apart and inspect the polymer filter element and be sure it is clear and not fouled. So next be sure the fuel line does not have an air leak. Pressure test the fuel line to no more than 10 PSI and it should hold. Now pressure test the carb to 10 PSI and it should hold. That means the fuel pump diaphragm is OK and the needle is holding like it should. These are the basic tests for any fuel system analysis. Now you said the engine idles and dies when given the gas so that means the low side circuit is open and delivering fuel at idle but as soon as the throttle is opened the engine dies so we now can assume that the high side discharge nozzle is blocked and not delivering fuel. So the fuel molecule can make it's way to the engine trough the low side. I would suggest that you open the H screw a couple of turns and try starting the engine and revving it up at full throttle and keep blipping the choke open and closed to see if you can flush out the H side with fresh fuel and get the H side check valve to open up and let that fuel molecule through. The saw is running lean so be careful so you don't keep it running lean and score the piston. Either it will clear up real fast and be rich so you can tune it back to the proper setting. For that saw with a bar and chain attached it should be running about 13500 RPM.
So if this does not solve the problem the carb may be fixed by soaking it in an ultrasonic cleaner but in my experience the check valve may be ruined and probably not working any more. Sorry to be so negative.
Check the basics but if the carb has sat with fuel in it for any length of time the carb probably is ruined and will need to be replaced. The H side check valve is very delicate. The nozzle is replaceable but requires a special punch to do it right.
Check it out and post what you find.

wv logger · « **Reply #3 on:** October 25, 2008, 08:39:47 PM »

my dad had one and it did the same exact thing..it had a hole in the fuel line..took us forever to figure it out..you might want to look at that

joe_indi · « **Reply #4 on:** November 01, 2008, 07:54:22 AM »

Steve,
You say that on choke the saw fires but off choke it dies out.
Check the impulse hose.
This is the ribbed hose that runs from the crankcase to the carb.It supplies the impulses for working the fuel pump.
You can test the fuel pumping system very easily.
Remove the metering chamber cove(the one fixed with 4 small screws).
Put the carb back onto its mount.
Fit the fuel hose.(Check the white plastic nipple onto which the fuel hose is mounted.It should not be loose).
Keep the metering lever pressed down and crank the engine without the spark plug.
If everything is working fuel should spurt out through the metering needle.
If no fuel is spurting, trouble shoot from here in reverse into the fuel tank.
The small strainer above the pump diaphragm, the pump diaphragm, the air passage from the carb to the impulse hose, the fuel hose, the nipple I mentioned earlier and the pickup body.
By the way, was the spark plug wet or dry?
Joe

wannabeonetoo · « **Reply #5 on:** November 02, 2008, 07:26:24 AM »

Thanks for the tips guys,my buddy has left to go deer hunting for a couple of weeks so we won't have a chance to work on the saw .
We have lots to look at now ,thanks to the info. given to us here

.He has one of my Stihls with him to use if need be.
I'll be going to hunt with him a few days this week so I'll take any new info. to talk over in the evenings.
Thanks for the wealth of good information

It's great to have such a knowledgeable network to tap into .
Steve

wraylow · « **Reply #6 on:** November 04, 2008, 03:06:19 PM »

you should also check the boot that connects the carb to the cyl. sometimes they rip if the saw is hung up and pulled on , the rubber mounts stretch and the boot is also stretched. If it has the black ribbed fuel line that is the most likely culprit. they tend to dry rot and crack .

wannabeonetoo · « **Reply #7 on:** February 26, 2009, 09:58:06 PM »

Well it's taken me this long to get it back from him !!!!
The fuel pick-up line in the tank was completely disintegrated

. It was in 3 pieces,shrivelled up and brittle !!
So I replaced it and added a carb kit.
It took a little coaxing to get going , but when it did it was as good as ever

I suspect it was the ethanol in the fuel . I have him talked into hi-test and marine stabilizer from now on.
I'm still in shock over the deterioration of the line !! This is my first experience with the hazards of ethanol in fuel (if that was the culprit).
What other problems are you experienced motorheads seeing , and what should I keep an eye out for

?
Thanks for your help guys.
Steve

Al_Smith · « **Reply #8 on:** February 27, 2009, 04:32:08 PM »

The ethanol didn't eat the fuel line up,old age did .

I've repaired saws that were old enough and had sat long enough that the fuel line was just jelly in the bottom of the tank .The last they had ran before they got shelved was way before they got the bright idea to put hi tech moonshine in the gas .

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