B&S 675 engine won't idle

[brehm62]

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.

 

[Rivets]

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.

 

[brehm62]

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

 

[Rivets]

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

 

[brehm62]

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

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.

 

[Rivets]

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

 

[brehm62]

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

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.

 

[Rivets]

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.

 

[Rivets]

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.

 

[brehm62]

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.

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.