Toro Push Mower Engine Revs Up and Down

[tim the pacesetter]

Thanks. Throttle plate - got it!

I seem to have 2 welch plugs. When disassembling the carb the first time, one just fell out on its own. I didn't remove the other one because it appeared stuck in there. There's
a little groove/hole on the side that I tried to pry up - but I didn't want to use too much force. Should I just go ahead and really try to pry it out?

 

[slomo]

Thanks. Throttle plate - got it!

I seem to have 2 welch plugs. When disassembling the carb the first time, one just fell out on its own. I didn't remove the other one because it appeared stuck in there. There's
a little groove/hole on the side that I tried to pry up - but I didn't want to use too much force. Should I just go ahead and really try to pry it out?

Plugs are glued into the carb body. Can be pretty tough to remove. Remove using brute force and a gentle hand simultaneously. The one that fell out needs to be reintalled and sealed. They make Indian Head Shellac which glues and seals these into the carb body. Glue the plug in then seal the round area.

 

[slomo]

Take a bread tie. Strip off the vinyl or plastic covering, leaving a thin wire. Probe all the tiny holes in the carb body and any jets accessible. Spray with carb cleaner and SAFETY GLASSES. I will inform you that if you get that spray in your eyes, it burns like fire. Don't be all cool and try to spray away from your eyes...... That spray KNOWS where your eyes are and will jump in there before you can spit.

 

[tim the pacesetter]

Thanks for the bread tie tip! That's a great idea. I appreciate the tip on the shellac too.

You are absolutely right about the carb cleaner and how it behaves. The first time I sprayed the carb cleaner on the carb it splattered all over the place - including my face and eyes! It's a miracle none got in my eyes themselves. I mean, I was swiping my eyes with the back of my hand - when that area got hit by the spray too. Next time - goggles or safety glasses. Oh, and I should probably look for the small red spray straw taped to the side of the can next time too. I got lucky - could have been a trip to the ER.

My lawnmower is at a relatives house, and when I went back and snugged up the crankcase breather tube today the engine the surging pretty much went away. The new tube arrived today. I'll install it pretty soon.

 

[tim the pacesetter]

Hey guys, just wanted to come back and thank everyone for your help. It turns out it was the carb, after all. After I rebuilt it, the mower ran pretty close to perfect. But, I sensed a small amount of surging and figured if I got the float positioned right things would be fine. Well, after I reinstalled the carb after the float correction I could never get it to run right again.

The last step I took was to install a cheap aftermarket carb. No matter what I tried I couldn't get it primed - even after I removed the air filter and poured gasoline through the opening there.

In the end, I had the shop install a brand new Briggs & Stratton (OEM) carb ($41) and they were able to get it running great again. All the shop did was remove the "chinese" carb and install the OEM one - plus they put fresh fuel in the tank.

Just did the lawn yesterday so now I'm back in the game. Thanks again for all your help!

 

[bertsmobile1]

Thanks for coming back
I am sure when people come here and see all of the techs advocating to use either genuine OEM parts or certified ones from a mower shop they think we are paid stooges for the industry.
However it is just we see all of the dud ones come in for repair.Naturally people who won the parts lottery & got good don't come in so our opinions are a bit biased.
At a guess about 1/10 of what comes through my gate is faulty ebay/amazon parts used to fix a problem that could have been done easily by cleaning &.or adjustments.

 

[tim the pacesetter]

Thanks, Bert. I was lucky to get an OEM carburetor for my roughly 15 year-old Toro 20038 mower for $41. The chinese/after market carbs were running anywhere from $10 (this carb didn't fit) up to about $30. So, at $41 for an OEM replacement this seems reasonable. I could have used the original carb but since I had my hands on it (meaning I could have damaged it somehow) I figured it would be cheaper to just put a new OEM one in. This way I wouldn't have had to pay a tech to rebuild the original one.