Stihl MS290...New Carb/Plug. Fuel coming out of muffler, won't idle

[clattin]

Hey all,

I just put a new carb, plug, fuel line, fuel filter and air filter on my MS290 (because it wasn't starting and they were really old). Anyway, I can get the saw to run at high idle when I have it in the half choke position (one notch up from full choke), but when I pull the trigger to shut the choke off the saw dies and there's a LOT of fuel coming out of the muffler.

I'm handy but no true mechanic. Is this likely a bad cylinder? Or maybe the carb adjustments aren't correct? This is a chinese Amazon carb and I didn't mess with the adjustment screws when I installed it.

Would love to hear your thoughts!

Thanks,
Chris

 

[KostasVolos]

Carb needs tuning.

 

[ballisticdoughnut]

OEM or aftermarket carb? If aftermarket take it off and toss it in the scrap bin. Get a kit for the original carb and rebuild it.

 

[Old2stroke]

Sounds like the carb is causing flooding. Could be control lever setting, wrong diaphragms, errors in assembly, etc. When you use an AM carb, you have to take it apart and make sure the diaphragms are the right ones and in the right order with the gaskets, control lever is set to the right height and the fuel inlet will pass a pressure test. It is unreasonable to expect the factory setting on an AM carb to be right for your saw. The carb ALWAYS has to be adjusted to get the correct tune for your saw.

 

[Captain Bruce]

Hey all,

I just put a new carb, plug, fuel line, fuel filter and air filter on my MS290 (because it wasn't starting and they were really old). Anyway, I can get the saw to run at high idle when I have it in the half choke position (one notch up from full choke), but when I pull the trigger to shut the choke off the saw dies and there's a LOT of fuel coming out of the muffler.

I'm handy but no true mechanic. Is this likely a bad cylinder? Or maybe the carb adjustments aren't correct? This is a chinese Amazon carb and I didn't mess with the adjustment screws when I installed it.

Would love to hear your thoughts!

Thanks,
Chris

I concentrate on these 1127-series saws, and enjoy the simplicity. The carb from china is your issue. It is flowing fuel beyond the impulse draw, and straight thru the jug, and out the exhaust.

Get rid of that carb, I have dissambled them more than once, to discover missing air passages absent from the mfgering....TRUE story.

 

[thompsoncustom]

Start with tuning the carb even OEM ones need tuned. Your high speed will need turned it but look up some videos if you don't know how to set the high speed.

 

[stihltech]

China Carb/ Always buy at least 2 so you might get one that works. Pressure test the carburetor to verify. You did test spark, correct? A weak spark is a possibility

 

[Sidecarflip]

Chinese are good copycats but don't always make them right. Get yourself a genuine Walbro rebuild kit and rebuild the old one and toss the Amazon crap. Even the Chinese carbs can be rebuilt with a Walbro kit, so long as the internal passages are all there.

 

[clattin]

Ok...sounds like the consensus is rebuild the old carb and trash the new one.

I did take a video of what it's doing.

Thanks!
Chris

 

[Sidecarflip]

Learned a long time ago that Chinese stuff can be good (with proper oversight) or bad with none. I just bought a Veyvor (Chinese) chain grinder for 102 bucks for grinding just rakers. My Oregon (Tecomec) grinder was 210 bucks. Interestingly, the Veyvor is just as good as the Oregon (Tecomec) other than a weak return spring (which I replaced with an Oregon spring, so you can actually get good stuff but, and I say but, it's always a crapshoot. Far as carbs go, I'd get an OEM or rebuilt the old one. Walbro sells rebuild kits and interestingly, the Walbro kit also fits the Chinese carbs.

 

[Patrick1903]

Ok...sounds like the consensus is rebuild the old carb and trash the new one.

I did take a video of what it's doing.

Thanks!
Chris

@clattin Any luck yet?

 

[Ed Penney]

G

Hey all,

I just put a new carb, plug, fuel line, fuel filter and air filter on my MS290 (because it wasn't starting and they were really old). Anyway, I can get the saw to run at high idle when I have it in the half choke position (one notch up from full choke), but when I pull the trigger to shut the choke off the saw dies and there's a LOT of fuel coming out of the muffler.

I'm handy but no true mechanic. Is this likely a bad cylinder? Or maybe the carb adjustments aren't correct? This is a chinese Amazon carb and I didn't mess with the adjustment screws when I installed it.

Would love to hear your thoughts!

Thanks,
Chris

go through the carb while the gaskets are still soft, adjust the float (vacuum diaphragm) run the hi/lo mix screws in and seat them. Back the low out 1 turn the high 2 turns adjust running sometimes the chiny carbs mixer screws are way not the same as a walbro adjustment. In my experience a rebuilt walbro is ten times better, 1 in ten Chiny clone carbs are rejects. They only have one size jet to cover all the engine sizes ms250 to ms390 it don't cut it and they don't care. they already have your money.

 

[stihltech]

1 in 10 are rejects? My experience is 1 in two.

 

[Ed Penney]

1 in 10 are rejects? My experience is 1 in two.

yea, your right, I worded that wrong should have been one outta ten work if your lucky. I don't even buy that crap any more. Even the cheapest crap OPE from China has a Zama or a Walbro on them, they don't even use their clone carbs on their own junk

 

[Sidecarflip]

1 in 10 are rejects? My experience is 1 in two.

Like everything in life, you always get what you pay for

 

[a. palmer jr.]

A lot of times people blame the carburetor when their engine has a small air leak. Best to do a pressure/vac test before buying too many parts. In this case I would check the carburetor first, however.