Need Help. Toro MX4250 Surging

[Bartman71]

bertsmobile, thank you for all the quick responses! :thumbsup:

I ordered the proper cleaning tools from Amazon and they'll arrive tomorrow. Wow!

My carb has the name Huayi engraved on the top of it. I assume this is the company who makes the carburetor. I'm not having much luck finding information in this unit from the internet including the site you sent. Is there a way to tell which circuit is the highspeed and which one is for idle?

 

[bertsmobile1]

Should be on the parts breakdown.
Main jet is the high & idle jet will be the idle.
Your carb will be copy of one on the page I sent.
It is a Chinese copy.

 

[Bartman71]

I'll clean it again tomorrow.. One more question though.

The engine surges when running at full throttle without the blades engaged. It stops surging when I have engage the blades without changing the throttle (still on full). I just wanted to make sure this problem would still be the idle/low speed jet?


Thank you!
Bart

 

[bertsmobile1]

The engine is governed.
There are 2 circuits in the carb
They are not independent but overlap.
At WFO 95% of the fuel comes through the main jet & 5% through the idle jet or around those sorts of amounts.
So untill the throttle is open far enough for the main jet to fully overwhelm the idle, a blocked idle will cause surging
flat out without the blades running or the mower moving the throttle butterfly is barely open .
When you put a load on the engine then the throttle opens up wide thus bypassing the idle jet problem.
Get some one to sit in the seat & work the controls while you watch the throttle open & close.