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I have a B & S Brute 22" 675 3 in 1 self propelled mower. The problem is that it won't idle. I can start it and then if I manually close the choke vane part way it will rev the engine. It appears that the engine won't idle without partial choke.

Also, what is the concept of this engine with the auto-throttle? Is the speed supposed to be idle and then it tries to keep the engine from dying when you actually begin to cut? This seems unlikely. Is it supposed to be running full rpm? Or is it supposed to be some kind of fast idle? I guess this would be good to know to be certain that the auto-throttle is adjusted properly. However, I'm not certain how to check the rpm separately from the choke issue. I could really use some help with this.

I think the first issue is that the engine doesn't run well with the choke fully open. And, of course, the choke opens fully just as soon as the engine speed comes up to idle.

Today's mowers do not have a control for idling. They are designed to run at top speed all the time. If you have a throttle control on the hanle that would be a different story. If that is the case, please post the model and serial numbers for both the mower and the engine.

There is no manual throttle control; that seems to be controlled by internal centrifugal weights probably running off the camshaft. This then turns a shaft which moves the throttle lever on top of the engine under the plastic cowling and metal cooling shroud/rope starter. I've seen older designs that used this to prevent over-speed (throttle governor) but never for primary throttle control. Okay, so when I get the other fixed I'll have to set this to idle at high rpm.

Now, how do I fix the choke control? It won't idle without partial choke. Or are you saying that if I increase the idle rpm the choke won't matter? I'm having a hard time telling if something is not working right or something is out of adjustment. This not like any I've ever dealt with before (having idle and mixture screws).

The mower is a BTPV22675E

I didn't see an ID plate on the engine. There just seems to be one number stamped in the shroud:
126T05-4678-B3 09041456

Does the choke open fully after you start the engine? If it does, the auto-choke is working properly.

Rivets said:

Does the choke open fully after you start the engine? If it does, the auto-choke is working properly.

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Yes, that is what I was saying at the top. The choke is closed and the engine starts easily. Then the air from the flywheel blows the wind vane which opens the choke up. Then it won't stay running unless I partly push the lever back (partly close the choke). What should I adjust? Is it just that the throttle is too low of an rpm? It is not currently idling anywhere near max rpm.

Do not adjust the choke!!! It is working properly. I am going to find a thread that has picture to help out. Be patient.

Rivets said:

Do not adjust the choke!!! It is working properly. I am going to find a thread that has picture to help out. Be patient.

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I don't understand what you are saying. As far as I can tell there isn't any way to adjust the choke. I'm asking if I just need to adjust the rpm higher.

I said be patient. I understand what you want, but you keep talking about moving the choke. I'm trying to find you some pictures to help.

Do a search in this forum to find this thread. Re: b+s engine running very slow

Go to post #22 and tell me if you have a large spring like #1 connected as shown or to a vertical retainer.

Tell me what you find. If you have no spring or a different set-up let me know.

Rivets said:

Do a search in this forum to find this thread. Re: b+s engine running very slow

Go to post #22 and tell me if you have a large spring like #1 connected as shown or to a vertical retainer.

Tell me what you find. If you have no spring or a different set-up let me know.

Click to expand...

I assume you mean this picture:



That looks nothing like mine. If you need pictures of mine that is no problem; I'll take some.

Here are some pictures.

My suggestion would be to go through the carb thoroughly. Give it a proper cleaning and don't forget the bowl screw hole. Get a can of compressed air and blow through all the holes/carb jets. You can also use the wire from a bread tie or a pin to poke through the holes.
With the bowl off, reattach the carb to the engine and connect the fuel line. Use your finger to manually lift and lower the float to ensure that fuel flows through. Yes there will be some fuel spilling so do have shop towel handy to absorb the splashes.
Once you can verify that fuel has a steady flow, disconnect the fuel line and put the bowl back on. Don't overtighten the bowl screw either.

Good luck.

Please take some pictures, I'm a little confused as to which carb you have.

Rivets said:

Please take some pictures, I'm a little confused as to which carb you have.

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Are you saying that you need more detail? I already posted 6 pictures. Look at the top of this page.

Sorry missed those, working on second cup of coffee, quess I need to make it stronger. The larger spring needs more tension. Bending the metal plate out, where the spring is attached, will increase your engine speed. Do it in small increments as too not over rev the engine.

Rivets said:

The larger spring needs more tension. Bending the metal plate out, where the spring is attached, will increase your engine speed.

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No, I can increase engine speed by loosening the clamp on the throttle arm and moving the arm very slightly and then re-clamping. I included an arrow in the picture to show where this is.

Do it in small increments as too not over rev the engine.

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This I wholeheartedly agree with.

That is not the throttle, it is the governor, please do not adjust here unless you have had experience. Let's back up. You originally said that the engine will not idle. It is not set up to idle. Once the engine starts, it is designed to come up and stay at full throttle. The only speed adjustment on this engine is to raise or lower the top engine speed by changing the spring tension I talked about earlier.

Rivets said:

That is not the throttle, it is the governor

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Yes, a self controlling throttle is a governor.

You originally said that the engine will not idle. It is not set up to idle. Once the engine starts, it is designed to come up and stay at full throttle.

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Yes, I did not realize that the engine was supposed to idle at full rpm. Now that I know that I can adjust the governor. In other words I should think of the mower engine more like a generator motor. Naturally this is different from any other lawnmower engine I've ever seen.

The only speed adjustment on this engine is to raise or lower the top engine speed by changing the spring tension I talked about earlier.

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There is no spring tension adjustment. I can however adjust the position of the governor arm.

You are not getting it. The governor is not adjustable. It is designed to be set once and not changed. This setting is done with the engine not running and with the throttle in the wide open position. The speed of the engine is adjusted by the tension on the spring. If this is not making sense to you, my suggestion would be to see a service tech, as by doing what you are saying is putting yourself and anyone who is around this running unit in danger.

Refer to the last picture in the first series that you posted.
The governor spring is the one running front to back, or alongside the spark plug lead.
There is a small tab where it's hooked on that you can bend forward just a bit.

Okay, I think I have the information you need. I can start the mower and it will run for about one minute. The speed seems fine. Then after that it begins to die. Manually altering the throttle has no effect (so it is obviously not the governor). However, manually partially closing the choke makes it rev higher. So, what does that indicate? The float bowl is not keeping up?

What does that indicate? It means that when your engine is hot it starts running lean. Where would I start. First, remove the fuel line and make sure the fuel is running freely. If it is I would have someone build the carb.

Grassbandit said:

My suggestion would be to go through the carb thoroughly. Give it a proper cleaning and don't forget the bowl screw hole. Get a can of compressed air and blow through all the holes/carb jets. You can also use the wire from a bread tie or a pin to poke through the holes.
With the bowl off, reattach the carb to the engine and connect the fuel line. Use your finger to manually lift and lower the float to ensure that fuel flows through. Yes there will be some fuel spilling so do have shop towel handy to absorb the splashes.
Once you can verify that fuel has a steady flow, disconnect the fuel line and put the bowl back on. Don't overtighten the bowl screw either.

Click to expand...

I think you're right; I need to check the float bowl. It may not be getting fuel fast enough to keep up with the engine.

I have this same mower. I let my nephew barrow it and somehow he broke off the little piece that controls the choke. Does anyone know where I can find another one? Also, all the parts that I will need to fix it?
thanks

justicejamesb said:

I have this same mower. I let my nephew barrow it and somehow he broke off the little piece that controls the choke. Does anyone know where I can find another one? Also, all the parts that I will need to fix it?
thanks

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partstree.com

Simple, just take your model numbers to your local repair shop and they can get you the parts you need.

justicejamesb said:

I have this same mower. I let my nephew barrow it and somehow he broke off the little piece that controls the choke. Does anyone know where I can find another one? Also, all the parts that I will need to fix it?
thanks

Click to expand...

jackssmallengines.com has parts break down and usually ahve the parts in stock

Were you ever able to figure out the problem? I'm trying to fix the same mower/issue for a friend. I've taken everything apart including the carb and can't find any obvious issues. Like you, manually closing the choke allows it to rev (seemingly) normally.