25 cc weedeater..new carb, new ring and piston, new gaskets, good compression..won’t start. when removing plug and looking into cylinder after …

Chainsaw stalls Chainsaw is 4 years old and has a history of moderate use. After I ran the saw about 1 minute on plain gas (grabbed the wrong gas can – ouch) the chainsaw sputtered and stopped.

It didn't seize, and the pull starter never became more or less difficult than normal. The engine would continue to start if I pressed the prime bulb and engaging the choke, but stall again after 10-20 seconds. The temperature that day was about 50 degrees F and I was running the saw with the “cold plug” installed (per warm weather running).

When it refused to keep running I did the following:
Flushed the fuel tank (that's when I saw the gas had no oil in it).
Ran hardware wire through all of the fuel lines.
Replaced the fuel filter and spark plug.
Cleaned the air filter with a nylon brush and compressed air.

Same behavior (start then stall in less than 20 seconds). I made at least 20+ attempts to start it.

I removed the carburetor and, though it looked perfectly clean, I took off the top and bottom covers then sprayed everything with automotive carb cleaner and blew out the passages with compressed air. The gasket and diaphragm looked new. No pinholes in the diaphragm when held against a bright light. I reinstalled the carb but got the same behavior (start then stall in less than 20 seconds). I again made at least 20+ attempts to start it.

I disassembled the short block and saw that the piston has some slight scoring on it. The ring is clean and I verified that the piston ring has .001 clearance between it and the piston ring groove all the way around with the ring held tightly in place (I was thinking that the piston might have become deformed if it did indeed get too hot when run without any oil premix).

The cylinder wall has no scoring and there isn't any signs of melted aluminum anywhere. The crank is clean as was the inside of the crank cover.

I reinstalled the crank cover using permatex non-hardening gasket goop and torqued the cover bolts to 10 inch pounds. I reassembled everything else per the exploded diagrams in Echo's “parts manual” for the CS400.

During assembly I took note that both the carb gasket and intake boot look like new.

Still the same result: press prime bulb once, engage choke, pull a few times and it starts but stalls after 10-20 seconds.

I'm stumped.

I have a husqvarna 323L string trimmer. I stored it after running the tank & carb dry for about two years. I fueled it, then started it, & it ran for a minute then died like I turned the switch off. Since it would not restart, I found the fuel filter had broken off the hardened fuel line & it sucked gummy crap out of the tank & into the carb. Failing at cleaning the carb, I finally put a new carb on it & replaced the pump, hoses & filter. It has ran good till this year. I winterized it with stabilizer & left it with a full tank over the winter. The gas in the tank was gone when I got ready to use it this year. I filled the tank with premix, checked for leaks, then started it. It would run fine for about half a tank, start idling poorly (lean) then cutoff & refuse to restart till I refilled the tank. I finally found the tank had cracks & was letting pressure out of the tank & apparently this was causing the carb to lose it’s ability to siphon gas out of the tank. So I replaced the tank which came with new hoses & a filter, which I properly installed to the carb. It cranked right up, but when it runs a half tank, the carb quits sucking gas out of the tank. When I pump to prime the carb, it moves the fuel into the carb, but the pump never gets hard like it does when I prime the carb when the motor is cold. I have to keep refilling the tank, prime, & then it starts & runs until the tank gets about half empty. The new fuel filter is down in the gas tank properly, but It will not run after it shuts off until I refill the tank & prime. I’m baffled. New tank, new hoses, new filter, new carb, & I can find no leaks in the fuel system. It runs strong. The 323L is a two-stroke & it always cranks on the second pull from cold on a full tank. Any ideas?

Have a craftsman 16″ chain saw 358.360260. Could not initially get it started after it had sat for a couple years with fuel stabilizer in it. When I went to use it the fuel had all evaporated and the fuel pick line was rotted. I replaced that with some difficulty but finally got it on. Saw still wouldn’t start. Replaced the fuel filter. Still wouldn’t start. Pulled the carb apart and cleaned and recleaned everything. Diaphragms were good and I didn’t adjust any of the mixture screws because as I said it ran fine before storage. Non of the carb passages were clogged. Fresh gas 40:1, good spark plug and good spark. Airfilter is good. Engine has maybe about 4 hours of total run time on it. It’s a ZAMA (?) carb. It will run for about 30 seconds when I manually prime it by pouring a small amount of fuel directly though the carb. When I was disassembling the carb the vent hose that goes back into the fuel tank seemed to have a small out of ?substance? in it which I cleaned out. It was right at the end the of the hose that goes back into the fuel tank and not up by the carb. It didn’t appear to be like your typical gummy deposits/varnish though. I hope it wasn?t some type of spongy check valve stuff that is supposed to be in there. That might explain some of my problems. Anyway, I also can not seem to get the primer bulb to fill. When I open the fuel tank, look in side and depress the primer bulb, air bubbles come out of the fuel filter. But when I let the bulb reexpand there’s no fuel that gets sucked up the hose. I can however seem to fill the primer bulb when the fuel tank is full and the chainsaw is laying on it?s pull cord side and the bulb is depressed a bunch of times. The saw will also start and run again for about 15 seconds then die. It’s definitely not getting/fuel and probably running out . Thanks.

25 cc weedeater..new carb, new ring and piston, new gaskets, good compression..won’t start. when removing plug and looking into cylinder after priming and attempting to start there doesn’t appear to have any fuel in the cylinder. plug is new.. other than running over it with a D9 tractor is there any hope..A.T.

I have a craftsman 25 cc string trimmer with fuel problems. After winter, ran tank of good fuel through it and it worked fine. Added fuel (unknowingly with water in it) and it ran on a slow idle and finally died. Drained fuel, took carb apart and cleaned, blowed out carb and reassembled. Still only ran on a slow idle – no throttle response. Took cover off with air cleaner and it ran fine. Seems to blow too much fuel out where filter sits. Put filter back on and runs on slow idle. Almost seems it is flooding, but have not adjusted anything, just cleaned. What do I need to do next?

I have a John Deere L118 Limited Edition (w/ 20 HP B&S engine), which I purchased about 8 years ago. It ran well with few problems up to late this summer. I believe the problem started when I accidentally filled the tank with some stale gasoline – the tractor turned over, but would not start. I drained the fuel tank and filled it with fresh gas, but it still would not start. When I use starter fluid, the tractor starts for 4-5 seconds, and then cuts off. I installed a new fuel filter. The connections in the fuel line seem tight, so while the problem might be the vacuum fuel pump itself, I do not think it is due to a leak in the line. I disconnected the fuel line at the carburetor — fuel flows through the line at start up. But when I put the fuel line directly into the air intake (with some starting fluid), the engine still cuts off in about 4 seconds. I am not sure if the pump simply is not drawing enough fuel into the carburetor. I understand that, if it is a problem with a safety cut-off, the engine would not start at all (even for 4 seconds). My thought was that the problem may be a gummed up carburetor, but that would not explain why the tractor does not start when I feed fuel directly into the carburetor. Any thoughts about other things I can try before bringing the tractor to a mechanic?

Replaced primer bulb and all fuel lines still getting air in lines. ran pretty good for about 10 minutes now will start with choke but dies in a few seconds. Cannot rev. up. cleaned under both plates but did not replace any gaskets on carb. After turning carb on its side it quit sucking air into primer bulb but same results. Not positive of routing of fuel lines they broke off before I could see how they were run.

I have a John Deere LX280 that won’t start. Have good spark, good fuel flow through fuel filter, and fuel in the carb bowl, but no fuel at the either of the plugs. Suspect either the safety shut off switch under the seat, or the solenoid under the carb bowl, but not sure how they are designed to work, or how to bypass them for troubleshooting purposes. Can anyone help shed some light on how the seat switch and carb bowl solenoid work, and offer any suggestions for how to get fuel to the plugs?