I have a craftsman 917298231 tiller, that has a 3hp briggs and stratton motor. The problems seem to be that it is not getting any fuel. The motor will run for a short time when gasoline is poured in the...
Hi, I will try to help you solve this problem by checking the easiest things first. Do you have a shutoff valve under the tank and is it open? Did you check for dirt inside the tank that might be blocking gas flow, and the fuel line also? Have you looked for loose bolts and gaskets at carb that could let air in and prevent suction bringing gas in combustion chamber? When was it last used and how old is the gas in the tank or has everything dried out? As gas evaporates it leaves a sticky sludge that can plug up small ports or like the inlet needle not letting fuel in.
I really think the problem is with the carburetor either adjustment or that it needs cleaning. Look at the carb and maybe even make a small diagram to remember where everything goes specially the governor rod and spring.
Shut off the fuel valve if you have one. If you don't go ahead and remove the carb from engine. Disconnect the governor rod and spring, the ends are just bent in a special way so you can slide them out of the holes by moving the carb in different positions. Remember which holes they come from, (very important) and try not to bend anything. A little patience is helpful. Now remove the fuel line, lift up the carb as you do and get a golf tee or a pencil to plug the fuel line so gas does not come out.
Remove the special bolt at bottom of carb, it has small holes drilled into it that have to be cleaned very well as they are part of the high speed mixture circuit. Look for a very, very small hole drilled on the side of this bolt towards the thread end of it. There will be a slot machined in the threads and this is where this hole is. Make sure it is clean, (do not use any wires to clean these passages as they might be damaged) The high speed mixture adjustment needle is usually part of this bolt machined into it but not always. If it is not then the high speed port is fixed and has no adjustment.
Now you will find the float, gently move it up and down to see if the inlet needle might be stuck which could be the main problem, not letting gas in. The float is held on with just a pin that you pull out to remove the float and inlet needle. (before removing the pin look for a little wire clip that holds the inlet needle to the float. Remember exactly how it is positioned) Now remove the screw situated on the side of carb, it has a spring on it. This is the low speed idle mixture adjust needle. (BEFORE removing either the high or low adjust needle, turn clockwise until GENTLY seated and remember the number of turns for each one)
Now clean all parts with paint thinners or carb cleaner. (NOT rubber parts) Blow low pressure air into all parts. On the outside of the carb look for a small vent hole, either on the low adjust screw side or the other side, it is again very small and has to be clear. (between me and you I sometimes cheat and use, being very careful a small brass wire or stiff plastic to help clean ports and passages when badly plugged. If you decide to go that way, you do on your own.) Before reassembly check needles for any damage like having been seated too hard and they are marked. If any damage and gaskets don't look too good get a carb kit, they are not that expensive.
Now carefully reassemble. A start for the high and low speed mixture adjust needles. The low screw on until lightly seated and back out 1 turn. The high speed mixture needle on the bottom of carb on bowl bolt, turn in until lightly seated and turn back out 11/2 turns. This is what the manufacturers suggest as a start that should get the engine going to make final adjustments, They are usually very close to being right. There is a screw on top of the carb, this is to adjust the idle speed so that when you release the throttle it will not stop on you. Adjust the way you like your idle speed to be at. I hope this gets you going. Final adjust of carb needle screws is not too hard if you take your time.
Do not go too lean, which means not enough gas in the fuel air mixture as it could make your engine run too hot. When you turn a needle screw in (clockwise) there is less fuel and when you turn out there is more gas in the mix of air and fuel. When you make adjustments go 1/8 turn at a time. Another point is when you push on the throttle to get more speed and it sort of misses or hesitates. turn low mixture screw out (counterclockwise) to get more gas in mix until it accelerates without missing.
Reinstall the carb on the engine, (you might need a new gasket, I suggest you get a new one) Be specially careful with the 2 governor linkages on the carb. If you got a carb kit there should be one included.
I hope I have given you enough info to do this. If you do this yourself I am assuming that you have a bit of mechanical experience as this is not that easy to do. I certainly hope this is helpful so best regards and good luck. I will gladly answer any more questions.
Feb 01, 2011 |