# Toro 621 Power Clear QZR - Only runs on choke



## ChrisPeace

Hey guys,


I am responsible for a fleet of snow blowers, all of them 621 Power Clear QZR's. I can do some very basic repairs, like pull cords, chute repairs, servicing the auger assembly, etc...

I do have one snow blower in particular that I'm just feeling over my head on.

It will ONLY start and run when on full choke. If I let it run for a few minutes it will struggle through running on half choke, but will die within seconds of me taking the choke off. 

I had read somewhere that it could be running lean, and since I did have a fuel leak I figured I would start there. I took apart the carburator, put a new float kit in (while I had it apart) and replaced the gaskets on either side of the carb (which is where the leak was coming from).

I now have NO leaks, but the problem persists. 

Any ideas guys. I'm really in a jam here and could use some troubleshooting.


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## detdrbuzzard

hello chris peace, welcome to SBF!! sounds like the carb is plugged up and you need to clean it. and if there is a fuel filter on your machine change it also


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## ChrisPeace

Buzzard, I took the carb off, and sprayed it pretty thoroughly with carb cleaner. Is there anything I need to do past that? When I had it off the machine I took the liberty of replacing the carb float and gasket, and I'm certain I did that properly. 

Any other suggestions? I'd love to have a list of small things to try. I honestly feel like maybe there is something simple here that is causing the problem.


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## db9938

Welcome, and does the bottom of the carb have a screw with a spring in it?


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## detdrbuzzard

did you take the needle out and clean it when you had the carb apart


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## ChrisPeace

Yes I took the carb apart and cleaned everything. 

If by the "needle" you mean the spiked needle that is spring loaded on the carb float then that was replaced with a brand new one, along with the float and the gasket. So everything in the carb is new essentially. 

The model I have is this one:

Toro | Power Clear® 621 QZR (38458)

If you go to the Manuals Tab, there is a Parts Manual which will show you exactly what I'm dealing with. 

I'm left with a couple ideas:

1) I see no "filters" such as air or fuel filters listed at all. So I'm not thinking there is any issue with air or fuel flow in the traditional sense.

2) Can someone please explain to me what the "Governor" does? I was looking at the blower and I see there is a hooked spring coil (Page 10 of the manual...shown as #1). It is adjustable. 

What is it "governing"? I'm left with a sneaking suspicion that this could be causing my problem and with a little adjustment it'll be OK, but its a hunch based on no experience whatsoever. 

Thanks so much guys! Almost a foot of snow coming by tomorrow night and if I could get this blower running by then it would really do a ton to help keep us from freezing to death.


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## detdrbuzzard

it might just be the lean condition that most new carbs are set to form the factory


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## ChrisPeace

William, 

Well this machine has worked in the past. We haven't had any issues in it until this year. It was stored in a dry location without any gasoline in the engine. I made sure I poured them out and that I ran the engine completely dry on all of them prior to storage.

If you look at the parts manual you will see that spring with the hook that goes through the plate with a couple holes in it. It looks like it controls the tension on that spring. 

What would making these adjustments do?


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## ChrisPeace

Actually its a solid linkage piece with a spring wrapped around it. I think its only there to help the thing snap back to position when it isn't engaged.


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## db9938

Did you back the "spiked" needle out, after hand tightening it? One and half turns, is a good place to start. 

Otherwise you would lean the engine completely out. 

The governor actually adjust the throttle in relation to what is commanded by the throttle control. As long as you did not touch this, or knock it out of position, then I would not suspect this.


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## ChrisPeace

OK, guys,

I have made some progress. I have disassembled the carb yet again and I don't know what I did, but there is a two piece mechanism in the carburetor. Its in the center shaft that goes from the fuel bowl into the upper chamber. I think some fiddling with it has allowed me to run it without any choke whatsoever, but now I'm faced with the problem in this video that I shot of the snow blower.

The first step shown is on full choke. The engine is noticeably quieter.

Second step is half choke. At this setting the blower runs the way the rest of them run without any choke at all. The engine does not struggle and it it will blow snow powerfully without any problems.

Third step is no choke at all. You'll notice the engine is running with a rhythmic stutter. It will blow snow but it will do so very weakly and you have to approach the snow very very slowly or else the motor will die. 

I think I'm on the right path in looking at the screw piece that is in the center of that fuel bowl shaft. Should I be tightening this screw piece or loosening? Loosening would seem to put LESS fuel into the chamber because the screw piece will start to block the two small holes on the side of the shaft that fuel goes through.

Anyway, heres the video:


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## db9938

Pm'ed you.


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## ChrisPeace

Problem solved! Thanks guys.

Turns out I was right. "Loosening" the screw for the nozzle actually obstructs the two fuel inlet holes = leaning out the engine. Tightening it has the opposite effect. 

Snow blower runs like a champ now!


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## lthomas

*Toro 621*

Hi Chris,

I seem to have the same issue with my Toro 621r, could you explain in detail exactly what you did to rectify the issue. 

Thank you in advance.


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## CleanCarburetor10

Hi Chris - Main reason why the engine runs at ½ choke is because the carburetor emulsion tube is plugged. This is the brass part that is mounted in top of the main jet. Even if you drain the fuel out of the carb, the capillary effect will keep the fuel inside the very small holes drilled along the emulsion tube. Remove the main jet and emulsion tube, replace them and you’ll be fine.
Watch this video: 






Stay tuned for CleanCarburetor kit that will prevent the small engines carburetors from problems like this. It’s something that it doesn’t exist on the market at this point. Check:

AT&T Website Solutions

in about 2 months.


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