I just replaced the fuel pump bulb on my Stihl FS 250 Trimmer/Brush cutter. It ran fine all day but the next morning it will not start. Spark plug is firing and it has fuel, but it won't even pop! I tried squirting a little fuel in the cylinder, thinking it might be the carburetor, but it still won't respond. Any suggestions? I really need to fix it myself, if you know what i mean.$$$.
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Why won't my Stihl FS 250 Trimmer/Brushcutter start?
- Thread starter fxgardner
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Export threadLawnranger
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An engine needs three factors to start and run properly - the correct air/fuel ratio, sufficient compression (arguably 90 P.S.I. or better) and sufficient spark at the correct time. If one of these factors is missing or out of proportion, the engine will run poorly or not start/run at all. Your task is to find the missing factor by inspecting and testing the systems involved. Which factor is missing or out of proportion in your case?
There are conditions that will prevent an engine from starting even though all three factors are correct such as a plugged muffler/exhaust, old/contaminated fuel and I'm sure there are more possibilities but I won't list them here so I am going on the assumption that one of the factors is missing and that all other components are functioning properly.
You will need a compression gauge to test compression so if you don't have one or don't have access to one you will need to take it to someone who can test it for you. You will also need a spark checker which can be made from an old, working spark plug by clipping off the side electrode and resting the metal hex of the spark plug on the metal part of the engine but this is not as easy as it seems as many engines have plastic shrouds and other obstacles in the way.
Perform the necessary tests and report back with your findings.
There are conditions that will prevent an engine from starting even though all three factors are correct such as a plugged muffler/exhaust, old/contaminated fuel and I'm sure there are more possibilities but I won't list them here so I am going on the assumption that one of the factors is missing and that all other components are functioning properly.
You will need a compression gauge to test compression so if you don't have one or don't have access to one you will need to take it to someone who can test it for you. You will also need a spark checker which can be made from an old, working spark plug by clipping off the side electrode and resting the metal hex of the spark plug on the metal part of the engine but this is not as easy as it seems as many engines have plastic shrouds and other obstacles in the way.
Perform the necessary tests and report back with your findings.
Thank you for your information. Spark is there. Fuel is good. I just took it down to the Stihl dealership where I buy my equipment. There is a magician there posing as a Stihl mechanic. He pulled it about 20 times. Nothing. Took the plug out, put it back in, just like another mechcanic and I did several times. Took the air filter out, put it back in, just like we did. Pulled it a couple of more times. It Started. He made a slight adjustment to the carb. It is now running great. He said "It was flooded!" You'd think with the other mechanic and myself trying to start it for two days, it would've gotten "unflooded" at least once! Thank you for spelling it out for me. The Mechanic's name who fixed it is Dana. He works for Randall"s Stihl Dealership in Beaufort, S. C. Oh. bye the way, there was no charge.
Lawnranger
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If I had a nickel for every flooded two stroke powered piece of outdoor power equipment that came to me, I'd be a much, much richer man. Stihl chainsaws rank among the highest as far as easy-to-flood-engines go.
Lawnranger
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The trick with Stihl is that you choke until you hear it bark, then remove the choke.
I've been preaching that for years but some people never get it. I usually don't charge someone the first time they bring their flooded saw to me but I do show and tell them the proper starting procedure (I even show them in the owner's manual where to read up on proper starting). If it happens again......
The trick with Stihl is that you choke until you hear it bark, then remove the choke.
Too true! In my experience, at the first sign of life out of the two-stroke stuff I have, shut off or go to half choke the moment it pops the first time.:wink::biggrin:
I just replaced the fuel pump bulb on my Stihl FS 250 Trimmer/Brush cutter. It ran fine all day but the next morning it will not start. Spark plug is firing and it has fuel, but it won't even pop! I tried squirting a little fuel in the cylinder, thinking it might be the carburetor, but it still won't respond. Any suggestions? I really need to fix it myself, if you know what i mean.$$$.
Hi Guys, Here is what I did for my fussy Stihl FS 250r trimmer....this after sitting all winter.
1) Removed the idle mix screw and sprayed Seafoam in the screw hole
2) Removed the high mix screw and sprayed in Seafoam in the screw hole
3) Replaced the screws at their factory(owners manual) setting
3) She started right up with one pull
4) I added some Seafoam fuel additive for the first tank only
5) Next season I will be more careful and drain the tank and fully run the trimmer out of fuel.....like it says in the manual ;-)
If your trimmer has a lot of hours I would also replace the spark plug, fuel filter, and air filter. The plug is gapped at 20 grand.
My fs250 has ran great for YEARS. All of a sudden it's flooded. Fuel comes out exhaust when pulling. Took carb apart and cleaned. It started right up then bogged down, and back to flooding. There is a diaphragm in carb. Could that be it??