Older 029 starts, runs 10-15 seconds, idles and then dies. HELP

Jim Spencer · July 17, 2014, 08:51:32 PM

After cutting about 30 trees into firewood, my 029 decided to quit. It will start easily run for 10-15 seconds, then will die to an idle for a couple seconds, then quit. I took the carburetor off today, opened the plate that is held with one screw, cleaned the small screen blew some air, reassembled, turned the high and low speed jets to their stops thinking I might loosen debris but there was no change. I did not want to open the rest of the carburetor because I am 79 and shaky. Had the same problem with my 028 and the problem was the small screen was plugged. I just wasn't that lucky today. Saw has very good compression and spark. I am convinced the problem is it is starving for fuel. Will continue to think this until I have eliminated all fuel problems. I can order a carburetor kit including the fuel line and pulse line but hate to fix something that ain't broke. Help! ?? This has been a very good saw.

Jim Spencer · July 17, 2014, 09:00:13 PM

I forgot to ask. How difficult is it to replace the pulse line and the fuel line?
I am quite a good mechanic but recently kind of shaky.
Getting old ain't for sissies.
Appreciate any and all advice.

LeeB · July 17, 2014, 09:46:31 PM

Could it be a plugged vent or plugged fuel filter.

Jim Spencer · July 17, 2014, 10:17:17 PM

checked the fuel filter and I can blow thru it quite easily.
thinking maybe the fuel line is kinked . even if the fuel tank vent is plugged it should run longer than a few seconds.
Tomorrow I will check fuel tank vent. I will also disassemble the carburetor completely clean and reassemble and also will remove fuel line and check it.
thanks for the suggestion.

joe_indi · July 18, 2014, 10:55:25 AM

Jim,
Your saw might have a blocked or damaged impulse line.Take the carburetor and spark plug off.Squirt some fuel into the impulse hose and pull the starter. The fuels should be blown out. If it doesnt happen, and if the line is just blocked, you could try to clear it by pushing about 3 inches of 2mm mowing line through the hose.
If the hose is broken there is nothing else to do but replace it.A bit painful to do, but 'do-able'
Hopefully the impulse has just come off the engine housing and needs to be only pushed back onto its connector.

By the way, the old Hindustan assembly line was closed down recently here is a link: http://in.reuters.com/article/2014/05/25/uk-india-autos-ambassador-idINKBN0E50D820140525
Joe

Jim Spencer · July 19, 2014, 08:01:31 PM

Joe, I checked fuel line, it's o.k. The pulse line has a very weak pulse. I did the check you suggested by removing the spark plug and holding the meter valve open while pulling the starter cord. I could not get any fuel through. I had disassembled carburetor and blew everything out with high pressure air before these checks were done. I tried checking the pulse line on my 028 and it has a noticeable more pulse than my 029. I forgot to run a 2mm plastic line through it to check for being plugged but I doubt very much that it is plugged just from the way it reacted when I put fuel in it. Not much blowing of fuel. I have a carburetor rebuild kit coming on Tuesday which I will use then.
I really think the pulse is very weak. Looking at this 029 I kind of dread trying to change the pulse line but everything points to it being the root cause. Any pointers ? Looks like it could get complicated. :'( Thanks for your help.

joe_indi · July 20, 2014, 04:23:35 AM

Jim,
From your post I assume that one of the following has happened"
1. The impulse hose has come off the engine block
2. The impulse hose is damaged
3. The impulse hose is blocked
4. (Heaven forbid) You have seized rings.

Well we both know the remedies for #3 &4.
Taking an optimistic view, you will need access in the simplest way to the engine end of that impulse hose.
The simplest way is to remove the screws of all the anti-vibration buffers (bushes). This would make it possible to lift the tank housing up and away from the engine block to give you easier access to the impulse hose. Its simple and needs the removal of just a couple of screws.
If you need any help with that let me know.

Joe

ladylake · July 20, 2014, 05:37:50 AM

Check the compression first, low compression = low pulse. If OK I'd put a new fuel line on even if the old one looks good plus cleaning the carb, some have a little screen in the inlet that would act like that. Steve

luvmexfood · July 20, 2014, 10:57:18 AM

I have heard the term impulse line. Am I correct it is the rubber line that goes to the opposite side of the carb from the fuel line and attaches to a brass nipple? Or is it the nipple?

ladylake · July 20, 2014, 12:00:36 PM

Yes on most saws it a rubber line running from the crankcase to the carb, as the piston goes up and down it blows air on the down stroke and sucks air on the up stroke which makes the diaphragm in the carb go up and down which pumps the fuel. Some saws don't have impulse hoses but have a hole in the base of the carb that goes to the crankcase. Steve

luvmexfood · July 20, 2014, 02:37:43 PM

Thanks. I never could quite understand how the fuel system worked. Why there was not some type of fuel pump. Your explaination turned that light bulb on in my head. I see the relationship now. Never did understand how the diaphram was made to move.

Again, Thanks.

Jim Spencer · July 27, 2014, 09:08:15 PM

Still waiting on my impulse hose and carb rebuild kit so I can get back to solving this problem.

SawTroll · July 28, 2014, 02:50:59 AM

Hard to Guess, with a cheaply made like that one.

ladylake · July 28, 2014, 05:29:09 AM

No matter what the quality 2 strokes all work the same. Steve

Jim Spencer · August 01, 2014, 08:37:46 PM

Happy to say my saw is now running like new.
Sorry to say I was not able to identify the root cause of this problem.
The chain brake handle was broken so to replace it I had to make a major disassembly. I had to remove the AV handle, Annular buffers, muffler and plate behind clutch brake housing. Also had to remove handle housing. Had minor problem reassembling chain brake bell crank. I will continue on another post.

Jim Spencer · August 01, 2014, 08:55:41 PM

I replaced the chain brake handle, even though I could not find any defective items, I replaced the fuel filter, fuel line, impulse line, air filter, small screen in carburetor, carburetor rebuild kit.
I was really intimidated by what looked to me to be a job for a highly trained technician but it really was not terribly difficult once I decided I didn't want to pay a fortune to have this done by Stihl. Possibly the fuel filter may have been plugged? Did not seem like it. May have been the fuel pump diaphragm?
I want to thank everyone for their input, especially Joe Indie who has been very helpful. Evan suggestions that are wrong gets the creative juices flowing and are helpful to problem solving. Any way my saw runs like brand new.
It is just too bad I could not contribute much to this great Forum.