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Hello, I have an MS260 and I went to start it this afternoon and it just wouldn't start. It almost acted like it didn't have gas. So I checked the tank and it didn't have much so I added a but more. When I'd pull on the pull starter it didn't sound like it normally does. Like it just didn't have enough oomph to get itself started. Like I said it acts like it may not getting fuel but not quite the same symptoms I guess is the right word. It's hard to explain. Just using the saw all the time I've gotten used to how it acts. It was working fine yesterday. I used it a good portion of the afternoon. The gas is also fine. It's a fresh mix.

I thought it may be the fuel filter. So I started to fish it out and as I was getting the filter through the gas tank opening the fuel line just ripped apart. I barely put any pressure on it at all. I was just adjusting the filter so it's make it through the tank opening. So I'm assuming the line had a crack in it or something similar and it was sucking air. At least I'm hoping so I don't have to do any further investigating.

Now to get to the point... Is there a way I can test the filter to see if it is clogged. I'm going to replace it along with the line obviously, but I can't get to the parts store until probably after 5 tomorrow and they close at 5:30 so I was to do as much troubleshooting as possible to figure out what all I may need so I can grab it and get this thing fixed by tomorrow night. I can't be without the saw when the weekend comes. I lost too much valuable time today.

So I was wondering if there is a way to test to see if the filter is clogged just to help me be more certain it was the line and the filter. Also, what else should I check while I am repairing the fuel line? I'll have things moved around and undone so I'd rather check it all then to make things quicker / easier?

Thanks.

You can blow through the filter to see if it is clogged. Will be hard to blow through if plugged. Most likely the problem was the fuel line, I replace several every year on stihl chainsaws. Mostly the ones on the ms170-180, 250, and 290. Something that could pop up is if the line has been split for any period of time, it can allow dirt to enter the carb, and plug the internal screen. I wouldn't pull the carb unless it doesn't run right after line and filter replacement

ILENGINE said:

You can blow through the filter to see if it is clogged. Will be hard to blow through if plugged. Most likely the problem was the fuel line, I replace several every year on stihl chainsaws. Mostly the ones on the ms170-180, 250, and 290. Something that could pop up is if the line has been split for any period of time, it can allow dirt to enter the carb, and plug the internal screen. I wouldn't pull the carb unless it doesn't run right after line and filter replacement

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Great info! Thank you.

To check the filter, put it in a bowl of water and blow through it slowly.
If OK you should see uniform tiny bubbles coming from all over the filter.

Don't leave the filter in there too long without blowing as water can clog the filter just as effectivly as dirt.

Personally considering the cost of a replacement it is a no brainer, get a new one.
Check & clean the carb as previously adviced

bertsmobile1 said:

To check the filter, put it in a bowl of water and blow through it slowly.
If OK you should see uniform tiny bubbles coming from all over the filter.

Don't leave the filter in there too long without blowing as water can clog the filter just as effectivly as dirt.

Personally considering the cost of a replacement it is a no brainer, get a new one.
Check & clean the carb as previously adviced

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I find that some times the two cycle fuel filters have a one way check valve in them. Don't know about your filter but if it dose this wouldn't work. Also why not a bowl of fuel instead of water? You aren't blowing through this filter with your mouth are you??

This may sound strange, but it could also be something plugging the muffler. I recently had a friend tell me he found Stink Bugs inside the muffler on one of his Stihl saws. If exhaust can't get out --- fuel/air mixture can't get in.
I recently had the #*#! Stink Bugs blocking the fuel line in my Ventrac -- I had to get them out of my gas tank and blow air back (with compressor) thru the filter into the tank.
Once the fuel line, filter, and tank were clean -- everything runs fine.

reynoldston said:

I find that some times the two cycle fuel filters have a one way check valve in them. Don't know about your filter but if it dose this wouldn't work. Also why not a bowl of fuel instead of water? You aren't blowing through this filter with your mouth are you??

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No an old coffee jar so I can get it close to my eyes ans see right through.
All fuel down here is dyed with a fairly intense dye.
And I blow throuhg it with the same pressure pump I use for testing the carb & fuel tank with.
I suppose I could use an alcahol which was clear.
You have to be able to see the actual bubbles as they emerge from the filter.

Blowing air our while in water is a lot different to sucking water into the filter and water blockages only happen with the felt ( Wabro ) type filters which I will no longer be fitting after the stock I have runs out.

I changed the fuel line and filter tonight, but it still won't start. The carb looked very clean. I inspected it pretty well before putting it back in. The air filter seemed functional. When I pull on the pull start the saw just gives a few little putters and just won't start. I'll check the spark plug next I guess and then the muffler. This thing just went from working perfectly to randomly not. Really odd.

Pull the carb off but leave the fuel lines connected.
Open the throttle completely and blow through the carb .
A vacum cleaner tpe blower works best but failing that you can use a compressor with a big bore air duster.
You should get a continious stream of atomised fuel coming out of the carb if all is well with it.
If it breaks up , flutuates or just dosent happen the problem is in the carb.
Naturally no smoking, point outlet out side and this can get you time inside if you do it in California

Have you inspected the primer bulb for hole or cracks. Replace if you find even the smallest one.

bertsmobile1 said:

Pull the carb off but leave the fuel lines connected.
Open the throttle completely and blow through the carb .
A vacum cleaner tpe blower works best but failing that you can use a compressor with a big bore air duster.
You should get a continious stream of atomised fuel coming out of the carb if all is well with it.
If it breaks up , flutuates or just dosent happen the problem is in the carb.
Naturally no smoking, point outlet out side and this can get you time inside if you do it in California

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You want me to blow through the butterfly? I don't have a compressor as I live in an apartment. Closest person I know with one is my father an hour and a half south.

@BlazNT
The saw does not have a primer bulb.

Well yes that was the idea, however your circumstances sort of kill that idea.
You mimiuk the operation of the carb and thus can see if it actually working or is blocked up.
Just a short cut I use to cut down the diagnosis time.
Not having a workshop makes this a bit on the impracticable side for you.

Thanks everyone. I pulled the spark plug off and it looks like it is due for a replacement. I knocked off some of the grime with a piece of fine sand paper and dabbed it kind of dry. It needs replaced but I don't think it is the issue. My scrench isn't really long enough to get the spark plug out without taking off the top cover but the screw on the top is very tight and I was close to stripping it a few times so I left it on and just positioned the scrench and finally got the plug off and then back on. I pulled the muffler and tried to start without the muffler.

Neither worked. When I pull on the pull start it sounds like it is trying to suck (almost sounds like trying to maybe suck air?) but cant in a way.