Motorproblems on Stihl MS 250 C

[MartDalb]

Just gonna throw down stuff I have experinced with different machines.
Perhaps you can check some of it....

Clogged fuel filter, yeah it sounds stupid, and it's rare, but I have lately had 2 machines which would stall and only just run idle, filters were clogged, I could hardly blow/suck air into it.

Faulty fuel line, can cause weird issues, suck in air, but can give enough fuel to just hear it start up, then die.

Fuel tank vent/breather, I had a ms250 that would go, but die fast, turned out the nipple for the tank breather was broken, had to drill a hole and use the rubber/grommet solution that some of the MS250 uses.

I might think of more ......

 

[Penge58]

A new non-original carburettor cost here in Norway about 450 NOK. And that is only the carb. I don't know what an original costs.
From ebay I get a complete kit with gasket, airfilter, fuelfilter and hoses for just 165 NOK inkluding postage.

 

[MartDalb]

A new non-original carburettor cost here in Norway about 450 NOK. And that is only the carb. I don't know what an original costs.
From ebay I get a complete kit with gasket, airfilter, fuelfilter and hoses for just 165 NOK inkluding postage.

Sounds about right....
The trick is to find someplace on ebay/amazon, that has descent quality aftermarket carburators etc.
There are some really ****** ones out there..... but also solid ones for sure.

 

[Penge58]

Just gonna throw down stuff I have experinced with different machines.
Perhaps you can check some of it....

Clogged fuel filter, yeah it sounds stupid, and it's rare, but I have lately had 2 machines which would stall and only just run idle, filters were clogged, I could hardly blow/suck air into it.

Faulty fuel line, can cause weird issues, suck in air, but can give enough fuel to just hear it start up, then die.

Fuel tank vent/breather, I had a ms250 that would go, but die fast, turned out the nipple for the tank breather was broken, had to drill a hole and use the rubber/grommet solution that some of the MS250 uses.

I might think of more ......

The fuel filter is new, replaced.
I will tear it down again and check the rest, including the membrane on the carb. If not the new carb set turns up in a couple of days.

 

[Penge58]

regarding that saw....

it sounds like it wants to go, but not getting fuel for it.
What happens if you hold the throttle and try to start it, after choke pulls.

A good guess is a faulty carb for sure.
I would like to see it from the inside, needle, height, membrane, gaskets etc.

The more pics the more we can try to help really...

I will check what happens if I hold the throttle when I start it

 

[Penge58]

Sounds about right....
The trick is to find someplace on ebay/amazon, that has descent quality aftermarket carburators etc.
There are some really ****** ones out there..... but also solid ones for sure.

https://www.ebay.com/itm/Carburetor...e=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649

 

[MartDalb]

The fuel filter is new, replaced.
I will tear it down again and check the rest, including the membrane on the carb. If not the new carb set turns up in a couple of days.

Make sure to check, fuel line, and the seating of it, does it seal tightly in that little hole?
Check if it's cracked, I usually use a pressure testure with a little nipple, but eyes and sucking into it also reveals issues, just make sure the tank is clear of fuel

Check the breather while you are at it. With the fuel lid closed, suck air into the fuel line, it should let you suck, but not blow (insert funny line about blowing and sucking here).

Also, pictures of that carb if anyway possible?

It's a damn hard job finding the issue sometimes, and we can only trust/hope that you have done the "engine" rebuild as it should. Oil seals sit correctly, and gasket/sealing correctly applied etc.

 

[MartDalb]

Items in that kit looks ok, except for that impulse line...looks a little off to me, but heck it probably works just fine. I trust you compared your carburator to the one in that kit right?

 

[Penge58]

Make sure to check, fuel line, and the seating of it, does it seal tightly in that little hole?
Check if it's cracked, I usually use a pressure testure with a little nipple, but eyes and sucking into it also reveals issues, just make sure the tank is clear of fuel

Check the breather while you are at it. With the fuel lid closed, suck air into the fuel line, it should let you suck, but not blow (insert funny line about blowing and sucking here).

Also, pictures of that carb if anyway possible?

It's a damn hard job finding the issue sometimes, and we can only trust/hope that you have done the "engine" rebuild as it should. Oil seals sit correctly, and gasket/sealing correctly applied etc.

Thank you for your help and hints.
Any particular parts, angle or so you want me to take carburettor pictures of ?

Yes I hope I have done the rebuild correctly. The engine was complete when I got it so I I have not been inside the engine block or worked on the piston.

 

[MartDalb]

This would be my choice, I trust CTS carb, have been using their parts for a while now.
Just for future projects

https://www.amazon.de/Vergaser-021-...placementKeywords=stihl+ms250+vergaser&sr=8-1

 

[Penge58]

Items in that kit looks ok, except for that impulse line...looks a little off to me, but heck it probably works just fine. I trust you compared your carburator to the one in that kit right?

Yes I compared it but of cause t here might be things I have overseen.
When I ordered it I still had hope on the old one to work.

 

[MartDalb]

Thank you for your help and hints.
Any particular parts, angle or so you want me to take carburettor pictures of ?

Yes I hope I have done the rebuild correctly. The engine was complete when I got it so I I have not been inside the engine block or worked in the piston.

So the Engine is an "aftermarket" engine? preassembled

 

[Penge58]

So the Engine is an "aftermarket" engine? preassembled

Yes. This is the one
https://www.ebay.com/itm/Engine-Mot...e=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649

 

[MartDalb]

Ah. This might turn out to be the issue. Not saying it is.
Lets just still hope the carburator, or a faulty fuel line etc. is the issue.

But I will tell you my story with aftermarket preassembled engine.

Bought myself a Farmertec engine for a Stihl 023, which had me pullling my hair out, so I finally gave in and bought a complete engine.

Got the engine, fitted it, fired it up, and it went, broom brooom, then died 15 seconds after.
After that, it would only sputter and sound like it wanted to run, but didn't.

I took the entire engine apart, only to find a ******, and i mean ******, solution to the bearing holding the crankshaft to the piston arm.
It could more or less not turn with that useless bearing, or...it wasn't really a bearing, just round metal on the metal arm.
I can post a picture later if need be.

I don't and won't ever trust aftermarket Engines.

You can try and test the engine you have.
Take the starter/robe cover side off, and turn the engine by hand, using the flywheel.
It needs to feel completely smooth and easy to turn that engine around.

 

[Penge58]

Ah. This might turn out to be the issue. Not saying it is.
Lets just still hope the carburator, or a faulty fuel line etc. is the issue.

But I will tell you my story with aftermarket preassembled engine.

Bought myself a Farmertec engine for a Stihl 023, which had me pullling my hair out, so I finally gave in and bought a complete engine.

Got the engine, fitted it, fired it up, and it went, broom brooom, then died 15 seconds after.
After that, it would only sputter and sound like it wanted to run, but didn't.

I took the entire engine apart, only to find a ******, and i mean ******, solution to the bearing holding the crankshaft to the piston arm.
It could more or less not turn with that useless bearing, or...it wasn't really a bearing, just round metal on the metal arm.
I can post a picture later if need be.

I don't and won't ever trust aftermarket Engines.

You can try and test the engine you have.
Take the starter/robe cover side off, and turn the engine by hand, using the flywheel.
It needs to feel completely smooth and easy to turn that engine around.

Thanks.
I will check that by turning the flywheel.
Is there a way to test the vacuum nipple ? When the piston goes up it should produce a vacuum that sucks fuel into the carburettor ?
Can that function be testet in any way ?

 

[MartDalb]

found the items in the bin...

See where my screwdriver points, that is an OEM Stihl bearing, you can just barely see the needle bearing underneath.

The top one...crappy aftermarket, metal on metal, no real bearing.
The engine will NEVER run correctly, if that metal on metal isn't 100% smooth.
Mine was surely not, you can clearly feel the metal touching and thereby killing the engine running.

 

[PV Hiker]

Disconnect the impulse line and put a dab of oil on the end. While moving the flywheel around the oil will move in and out of the line

 

[MartDalb]

It can be a little troublesome to take it off....if you can varify each end is connected you should be good.
The fault will be carburator, fuel line or bad engine.

 

[Penge58]

Disconnect the impulse line and put a dab of oil on the end. While moving the flywheel around the oil will move in and out of the line

Thanks. I will try that tomorrow. It's midnight here now

 

[Penge58]

found the items in the bin...

See where my screwdriver points, that is an OEM Stihl bearing, you can just barely see the needle bearing underneath.

The top one...crappy aftermarket, metal on metal, no real bearing.
The engine will NEVER run correctly, if that metal on metal isn't 100% smooth.
Mine was surely not, you can clearly feel the metal touching and thereby killing the engine running.

Thanks.
I will check by the flywheel tomorrow.