045 idles at WOT when hot?

[Stihl-in-Ky]

Have been milling with my 045 after second cut or so saw will start to only fast idle with throttle wide open.If left sitting and running may straighten out.Does anyone have a clue.So far I have replaced the spark plug,fuel pickup cleaned the carb then replaced with a used carb,checked exhaust port for carbon,checked ignition it has the bosch electronic ignition did not know what to look for there. Also thought it might help to choke it some it dies as soon as you touch the choke. Saw rens like a charm and starts great up to that point. Any help would be appreciated greatly.

 

[Scooterbum]

Sounds like crank seals.You need to pressure check your saw.Also check your carb gaskets real close for air leaks.
You can take a can of carb cleaner and spray the seals and carb base and if it returns to idle ,You've found your leak.Good luck Steve

 

[Lakeside53]

Assuming it idles just fine once it's going, it isn't seals. Sounds like it's too rich. Pressure test the carb (via the fuel hose in the tank) - you may have a leaking inlet needle because of a bad seat.

 

[Stihl-in-Ky]

Have already put on another carb it is used but what is the chance both carbs have the same problem?

 

[Lakeside53]

Anything is possible.... but the only way you'll know is to pressure test your carb/saw.

 

[Scooterbum]

I did'nt understand your post at first.Check the spark plug wire and see if it is shorting out anywhere.I had one that was rerouted by someone and they had it laying against the flywheel.It would start and run fine until it warmed up then it would barely run at WOT but would still idle fine.It was on an old Mac 610.Also check all your wiring connections and possibly disconnect the kill switch.Good Luck.

 

[Jacob J.]

Pressure testing the carburetor will show if the inlet needle lever is set wrong, the inlet needle seat is bad (as Lakeside53 was referring to), if the metering diaphragm is sucked in, or if there is foreign material blocking the needle or lever. If you're not sure about pressure testing or don't have a tester, just eyeball the metering area for foreign materials or things out of place.

You did replace the carburetor, but was it rebuilt before being installed? Any diaphragm carburetor that had sat may need to be rebuilt. Even if it wasn't used. I've pulled brand new carburetors off the shelf that I ended up having to put kits in because the rubber diaphragms had deteriorated.