Concrete Saw: Starts, Runs for a While, Then Dies
Does your concrete saw, start, run for a while, and then die? This is a common symptom, and we have listed the likely parts that could be the culprit. Instead of hiring a costly service to fix the problem, use our expert repair tips to fix your tool yourself. Always refer to your owner's manual for advice specific to your model.
Locate the carburetor underneath the air filter. Remove any covers necessary to gain access to the carburetor. Take out the air cleaner housing and filter. First, check the operation of the choke. The choke should be closed for start up and for the first few minutes, as the engine warms up. If the choke comes off too soon, it will cause the engine to die. If the cable is stretched, replace it by disconnecting it at both ends and installing a new one. This should solve the choke problem. Check that the linkage is not bent out of shape, impacting operation of the carburetor. Now, locate the adjustment screws.
To adjust the carburetor, start...
Locate the carburetor underneath the air filter. Remove any covers necessary to gain access to the carburetor. Take out the air cleaner housing and filter. First, check the operation of the choke. The choke should be closed for start up and for the first few minutes, as the engine warms up. If the choke comes off too soon, it will cause the engine to die. If the cable is stretched, replace it by disconnecting it at both ends and installing a new one. This should solve the choke problem. Check that the linkage is not bent out of shape, impacting operation of the carburetor. Now, locate the adjustment screws.
To adjust the carburetor, start with both screws backed out two turns from the closed position. One should be idle mix and the other high speed. Start the engine, allowing it to warm up for five minutes. You may have to keep the throttle open a bit, allowing the engine to keep running. Slowly turn in the low speed jet, until it starts to die, then back it out another ¼ or ½ turn.
Next, hold the throttle wide open and slowly turn in the high speed, until it really starts to smooth out, rev high, and starts screaming. Then, back this out until it starts to run rough or slows down. Turn it back in midway between these two positions. Keep playing with the low speed needle until you get a rapid, immediate response from the throttle and a good idle with the idle adjustment.
Next, play with the high speed needle, but always back it out from the setting – about ¼ turn or so – from where it runs the smoothest. This setting of backing it out will allow more fuel when under a load and keep your two-cycle motor from running too lean. Next, put a load on it and tweak the settings, just a tiny bit at a time. Also, make sure the oil/fuel is mixed at the proper ratio. Most will start and run with both screws open two turns.
Do not close off the high speed any more than necessary, no matter how well it turns. Some carburetors are fixed, meaning they have no adjustments. Clean out the carburetor with carburetor cleaner as they can easily become gummed up in a two-stroke engine.
To remove and check the muffler, start by removing the recoil and then take off the belt cover on the blade side. Release the tension on the belt by turning the adjusting bolt counter clockwise until it stops. Take out the water line by turning the saw on its side to access the bolt. Walk the belt off the saw pulley and then remove the blade assembly.
Locate the muffler and take it out. Now, start the engine. Let it run for a while and observe. If it appears to run fine without the muffler, try cleaning out the old...
To remove and check the muffler, start by removing the recoil and then take off the belt cover on the blade side. Release the tension on the belt by turning the adjusting bolt counter clockwise until it stops. Take out the water line by turning the saw on its side to access the bolt. Walk the belt off the saw pulley and then remove the blade assembly.
Locate the muffler and take it out. Now, start the engine. Let it run for a while and observe. If it appears to run fine without the muffler, try cleaning out the old muffler with carburetor cleaner and dry it with compressed air. Shake it – if you hear any noise or rust particles are falling out, then replace it.
Install the new, or cleaned muffler, back in the engine. Put the water line back on the saw, followed by the blade assembly. Reattach the belt around the blade pulley by walking it back on the pulley. Reapply the tension by turning the adjusting nut clockwise until it stops. Put the belt cover and recoil back on.
Readjust your carburetor settings to prevent the engine from running rich, causing the same problem to occur. See “carburetor” on how to adjust these settings.