ms390 dies and no restart

rk100 · November 15, 2014, 10:44:42 PM

hello, have a ms390, 24 in bar, 3/8 .50 chain. repaced fuel line from tank to carb 4 cords ago due to fuel spraying out st top of tank when engine reved. ran good first cord then secod cord it died about half way thur day and would only restart and die when i tried to rev up, let it sit and polished up the spark plug and then it ran good. did not trust it after this so i installed a new plug, filter in tank and air filter, got new gas and stilh oil mix, and went and cut another cord with no problems. then went back for my 4th cord but right away i had troubles. saw started ok and ran for several cuts and then lost power and died, restarted but died when reved, did this a couple of times and then would not restatr at all. removed plug and polished, checked air filter and let sit while i sharpened chain and then restrted but repeated issues after a few cuts. had a friend along with his saw and let him cut while i loaded but noticed that he had starting fluid along to get his saw going. i do not use fluid in my saw but thought it might be a way to deterime if the issue was fuel or spark so got my saw out and tried to start but no go, tried a little fuid and it started and ran a while then lost power and died, no restart after several trie so i tried the fluid again and got a brief run but died. i origionaly thought it might be the ignition system but now think it is running out of fuel at the carb. what pumps or pulls the fuel from the tank to carb? problem has only happened when hot and after several good cuts, and is very random. what should i be looking at? thank you

Compensation · November 16, 2014, 12:29:29 AM

Had a saw do that before and when I took the Carb apart, it was packed with saw dust. Might try that and if you haven't taken the Carb apart don't worry its not that complicated. As for the starting fluid, I wouldn't recommend that.

drobertson · November 16, 2014, 06:48:28 AM

You might consider replacing the diaphragm, kits cost 10 to12 bucks I think. I did have a faulty new one, so in case the new one does the same, don't always trust the new one. Air leaks are sometimes a trick to find too!