Toro lawnmower surge at idle when blade not engaged

[linkage]

I have a Toro Recycler 20333 lawn mower that starts on the first pull but is surging at idle. I received it as salvage so I don't know if this is a normal condition. I googled the engine, Briggs & Stratton 128T02-3256-B1 and found another person reported the same thing on a different forum (this forum won't let me include the link). Still, it doesn't seem right to me.

I have done these things so far but did not notice a change with any of them.
- I cleaned the carb (disassembly, got all the holes with thin wires) and everything looked ok.
- I blew out the air filter.
- I added a fuel filter (it appears this model didn't include one) and cleaned the fuel line.
- I sprayed carb cleaner around the carb while the engine was running to check for a leak.

What else could it be? I recorded a video of it happening:

 

[Rivets]

When you cleaned the carb did you replace the float needle and seat, plus make sure the the float was sitting level. Surging in you case is the result of a lean mixture condition. This is most often caused by the seat swelling over time allowing the float to close the inlet too soon. This means that the fuel level in the float bowl, resulting in a lean mixture.

 

[Boudreaux In Eunice La.]

Yes I agree with Rivets......... I see 2 springs in the video..... 1 of them does not look right for some reason... Maybe both ????

Something is not right with your setup for sure.... Can you take another video and show us the whole engine and the carb setup ??

Let us know Mon Ami ~!~!

 

[linkage]

Ok. I'm going to buy a new carb since they're $10 and I'll let you guys know how that goes. It's one of those primer-less models with an auto choke. The auto choke part appears to be working but the governor part is (I think) that part that's bouncing back and forth which is causing the surge. The carb has 2 throttle plates basically.

 

[Boudreaux In Eunice La.]

Your carb has 1 throttle plate and a choke plate...... The choke spring looks good to me , BUT the gov spring looks like it's toooo thick and strong..... My new springs I keep in stock do not look like yours....

Your carb is still dirty causing the surging....... More than likely....... Just cleaning the bowl does not cut the mustard, the needle seat and where it sits needs to be cleaned very well..... Where did you get that brand new looking gov spring ???

I hate chineeeeese carbs, always trouble with those, most of the time........

Let us know Mon Ami ~!~!

 

[shiftsuper175607]

I have a Toro Recycler 20333 lawn mower that starts on the first pull but is surging at idle. I received it as salvage so I don't know if this is a normal condition. I googled the engine, Briggs & Stratton 128T02-3256-B1 and found another person reported the same thing on a different forum (this forum won't let me include the link). Still, it doesn't seem right to me.

I have done these things so far but did not notice a change with any of them.
- I cleaned the carb (disassembly, got all the holes with thin wires) and everything looked ok.
- I blew out the air filter.
- I added a fuel filter (it appears this model didn't include one) and cleaned the fuel line.
- I sprayed carb cleaner around the carb while the engine was running to check for a leak.

What else could it be? I recorded a video of it happening:

You took off the springs when you removed the carb to clean...
The guys are saying you have the springs hooked up wrong.

Another carb...10 more...will not fix your problem.
Let them help you get the springs right.

 

[bertsmobile1]

Ok. I'm going to buy a new carb since they're $10 and I'll let you guys know how that goes. It's one of those primer-less models with an auto choke. The auto choke part appears to be working but the governor part is (I think) that part that's bouncing back and forth which is causing the surge. The carb has 2 throttle plates basically.

WRONG

The governor bouncing back & forwards shows it is working 100% as it should.
It is the symptom of the problem, not the problem

 

[linkage]

You took off the springs when you removed the carb to clean...
The guys are saying you have the springs hooked up wrong.

Another carb...10 more...will not fix your problem.
Let them help you get the springs right.

I only disconnected the governor spring and I put it right back the same way. There's only one hole for it to go into. The spring looks new because I sprayed it with carb cleaner since it was covered in gunk. New carb is already on the way, yesterday I ordered the Podoy 799866 Carburetor 491588 Air Filter combo from Amazon for $13.

The governor bouncing back & forwards shows it is working 100% as it should.
It is the symptom of the problem, not the problem

Yeah I shouldn't have said "caused by".

 

[linkage]

The new carburetor has gotten rid of almost all of the surge, but every so often I hear what may be the tiniest bit of a surge. I am watching the governor and it appears to barely move though, so it's not like it was with the old carb. I really thought I cleaned the old carb well but I guess I missed something or the float bowl was bad. Thanks guys

 

[Boudreaux In Eunice La.]

Linkage ,,,,,,, Does it surge when you engage the blades and cutting your grass ????

BTW I re read your post and you said you added a fuel filter.... Not a bad idea, but I noticed if you put a very fine mesh filter on those engines it will surge at idle and full speed.... Exactly like a fuel line going bad on the inside of it....