Toro Push Mower Engine Revs Up and Down

[tim the pacesetter]

Hi folks. My lawnmower revs up and down when try to use it. I think this might be called, "hunting and surging". The mower is about 10-15 years old.

I made a 10-second video and I'm hoping someone can view it and offer possible solutions.

Video Link:

Toro Carb before.mp4

drive.google.com

 

[mechanic mark]

Order a carburetor rebuild kit using numbers & manufacturer of your engine. Remove carburetor & disassemble completely & use an ultrasonic cleaner or just google how to properly clean a carburetor before rebuilding.

 

[tim the pacesetter]

Thanks, Mark. I'll look into carburetor rebuild kits and cleaning methods. I appreciate your help.

 

[bertsmobile1]

Step by step instruction with good photos are found on the out door power info site

 

[tim the pacesetter]

Thanks, Bert. I visited the site but when I searched for my Toro model number (20038) it didn't yield any results. From what I understand, it has a Briggs & Stratton engine. I'm wondering if I should check the engine for its own model number. I'm a few miles away from the mower location so I can't go look at it at the moment.

 

[bertsmobile1]

Yes check by engine make & model not by what it is fitted into
The carbs are all the same regardless os who is fitting them

 

[tim the pacesetter]

Thanks, Bert. I appreciate your help and for providing the outdoor power info link. Personally, I'd go straight for the rebuild. However, I have a relative that wants to install a new, non-OEM product. I'll wait until this $10 new carb bombs and then do the rebuild

 

[slomo]

That mower is definitely a keeper. Do what you can to get her running. Hard to find a better mulcher than that one. THAT was back when Toro made good pushers.

Definitely a dirty carb or fuel tank issue. Something is limiting fuel flow.

Remove fuel tank and flush it out.

Install new fuel line. Filter and a shutoff valve are good ideas too. Cheap also.

Like others said clean and rebuild the OEM carb. Don't go to ebay or amazon looking for Chinese carbs.

 

[tim the pacesetter]

Thanks, Slomo. I'll start with the carburetor first, and maybe move on to the other maintenance. I'm glad to hear this mower is a keeper. I'll take of it for sure.

 

[slomo]

On a mower that old I would do:

1.Clean and rebuild the OEM carb. This is your most likely issue. Also check for vacuum leaks.
2.Flush fuel tank and install new fuel line and filter if you have room.
3.Pull the head and de-carbonize the cylinder, head and valves. This is in your engine manual you need to download.
4.Remove the metal engine fan shroud. Clean the top, bottom and all around the block. Remove all grass, dirt, oil and bugs from the cooling fins. Clean the entire engine like it was new. As Bert said, there is clean and then there is CLEAN. Look behind the muffler and such. Go all CSI on her. This procedure is also a must do, in your engine manual.
5.While you have the head off, check valve clearance.