I have a 8 year old Stihl weed eater that is giving me fits. Sometimes it will run 10 seconds and when you restart it, then it might run 3 minutes next time. Recently it is getting less and less. I did put an EBAY carburetor on it early this spring. When it runs it has good power. Have been running Stihl 2 stroke oil with no alcohol gas. I don't think the exhaust is plugged. New spark plug this spring. Didn't know if anyone had experienced this and had found their problem. Thank you.
- Thread starter andy r
- Start date
zuhnc
Member
- Location
- Macks Creek, MO
I have two Stihl 4-Mix engines on the pole saw and straight shaft brush cutter, as well as a Stihl 023L chain saw. Run Amsoil 2-cycle oil at 100:1 mix; been running for years with no issues. No screen plugging or carburetor issues not caused by me. I had to replace one carb due to very fine dirt in the fuel, which clogged up the passageways; no damage to the engine, thank goodness. Couldn't clean it adequately. I also use regular 87 octane pump gas, with Sta-Bil in it, as I keep about 50 gallons on hand for these tools, the zero-turn and 8N tractor.
You might have a plugged tank vent. Does the time vary if the tank is full or empty? Faulty crankshaft seals can cause poor running, as well, due to loss of vacuum in the crankcase. Checking the screen would be the easiest thing to do. zuhnc
This post was edited by zuhnc on 07/08/2021 at 08:50 pm.
You might have a plugged tank vent. Does the time vary if the tank is full or empty? Faulty crankshaft seals can cause poor running, as well, due to loss of vacuum in the crankcase. Checking the screen would be the easiest thing to do. zuhnc
This post was edited by zuhnc on 07/08/2021 at 08:50 pm.
No, I did not replace the fuel lines. Did I hear that they crack? Maybe it starts to suck air? I will add that when it was quitting last week, once it stopped, if you filled the fuel tank clear full if would run until the tank was down about 3 inches from the filler cap then seem to stop again. Refill the fuel tank it would run until it was down 3 inches from the filler cap.
MarkB_MI
Well-known Member
- Location
- Motown USA
I had similar problems with mine. I replaced the carb with one off eBay, not much improvement. Bought an OEM carb, no change. Replaced the fuel lines and it runs like a champ now.
M-MAN
Well-known Member
- Location
- Bostic, NC
Sounds like you got the lines crossed and it is pulling fuel in from the return line. The return doesn't go all the way to the bottom like the line with the filter. If they are on correctly your filter line is bad.
That's quite possible--I had that happen recently to an old Weed Eater I got for free. Lines had cracked causing erratic operation and then had been put back on wrong. Put on new lines, routed correctly, and it's now running fine. Typically, though not cast in stone, the SMALLER line is the feed line and will go from the fuel filter to the carb body while the larger line is the return line and will come off the side of the primer and go back to the tank--usually only going in an inch or less. Many WILL run with the lines reversed, but not well, nor for long, and you can chase your tail doing adjustments when all you need to do is reverse the lines.
Steve@Advance
Well-known Member
Sounds like a bad fuel line inside the tank. Stay with the factory rubber lines. They are better than the clear yellow Tygon, fit better, last longer.
Could be the lines are reversed, the line by the primer bulb is the return line, the other is the pick up line.
Be sure to blow out the filter or replace it and that it lays flat in the bottom of the tank.
This would be a good time to dump and rinse out the tank.
There may be a tank vent line with a setscrew screwed into the open end of the line. Remove and clean the screw, it vents by letting a small amount of air vent around the threads of the screw.
Could be the lines are reversed, the line by the primer bulb is the return line, the other is the pick up line.
Be sure to blow out the filter or replace it and that it lays flat in the bottom of the tank.
This would be a good time to dump and rinse out the tank.
There may be a tank vent line with a setscrew screwed into the open end of the line. Remove and clean the screw, it vents by letting a small amount of air vent around the threads of the screw.
This is what I found with my Stihl weed trimmer stalling after about 15 minutes of running. Would only restart with maybe 3/4 choke and could run with partial choke a few more minutes and then no more restart 'til next time cold again. The studs and nuts that hold the carb in place reach into the air cleaner. The nuts needed snugging up. There would be enough expansion of the studs with 15 minutes of engine heat allowing for enough vacuum leak around the base of the carb to starve out for fuel. With nuts tightened it runs perfect.
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