i have a 25cc craftsman blower bought used,wont start. i have good spark, getting fuel, changed spark plug. St

Question

what i need to know if there is sheer key, and if timing is adjustable

Answer 1

Timing is not really adjustable on small 2 cycle engines, the lack of a valve train (replaced with a reed valve) lack the requirement for valve train components, therefore timing is controlled by engine vacuum (fuel) and the rotation of the crank (spark timing). My first suggestion is the carb, on a 2 cycle the carb is the most complicated piece of hardware and because it is designed to handle a more viscous liquid then pure gasoline it can get gunked up. Try spraying some engine start spray into the carb a few times and try to run the motor on open choke with no gas in the tank, if the motor still doesn't start then you could have a stuck reed valve. If the carb does turn out to be the issue try cleaning it throughly and use premium gas in your oil/gas mixture.

Answer 2

I'm gonna guess that you've got a Briggs engine in your craftsman. To start off the term 'died' is a very vague term. If it will crank a little bit but then it hangs in mid-turn then your valves could be out of adjustment. A way to test for that is to turn the flywheel on the top of the engine until you get past the hard spot (which is called the compression stroke), and then try to start it again. Another thing to look at is your new battery. If you didn't get the battery cables tightened down all the way then your starter will only turn at half speed and not engage the bindex gear. You could also have a bad ground on your starter solenoid. If you are adventurous enough and know what to look for you could try to cross-arc the posts on the top of the starter solenoid (usually located on the right wall inside of the engine compartment with a red cable running to the starter) with a screwdriver. If it cranks when you do that, then its likely its a dead solenoid. There's a whole slew of things that can go wrong that might just need professional servicing. Self diagnosis can only go so far if you don't know what to look for.

Answer 3

The two most likely items are the carburetor and compression. The carb is a diaphram type and it needs to be rebuilt every few years. It is an easy job and costs about $15 to do it yourself. The kit comes with instructions. Compression is important, without enough it will not start. With the sparkplug in, slowly pull the starter cord. You should feel definate hard spots as you pull the cord out. If it pulls out smoothly without the hard spots the compression is probably low. This could be caused by worn rings or damaged cylinder walls. You can replace the rings cheaply but it is a more in depth repair job. They do make cylinder/piston kits for them also. The cost may be more than the machine is worth. If it is made by Poulan I would susect the cyliner is bad. Remove the carb and the muffler and with a flashlight look at the cylinder walls. See if there are scratches. This would indicate the need for replacement.

Answer 4

A commonly overlooked problem on those 2-cycle engines is the exhaust. If you remove the muffler and take it apart, you'll find a fine mesh screen which is a spark arrester. Carbon build-up on this screen will restrict the exhaust flow and cause the engine to lose power and then not start. Another common problem is fuel lines. The rubber they're made of eventually hardens and cracks and then the engine can't draw fuel from the tank.

Answer 5

Gas was probably left in it and went bad in the carb bowl. Try dumping out the old gas and put in fresh. If you've already tried that, small carbs are a pain to repair and adjust. You'll probably have to take it to a repair facility.

Answer 6

yes there's a shear key, its under the fly wheel, and no its not adjustable, does the engine fire ? smoke come out of exhaust ? put some gas in the spark plug hole
put plug in then start, will it run ? gas line ,problem

Answer 7

you need to take it to a repair center. Dont tell them you bought it used, just ask them to take a look at it. a lot of craftsman products can be fixed for free at sears repair centers, but its not widely known.