Briggs & Stratton T128T02 3256-B1 No Speed Control

[PK232]

I have a ten year old Toro mower with a Briggs & Stratton T128T02 3256-B1 engine that after the auto choke opens up ( ~ 1 minute) runs full throttle. The normal position of the throttle plate is wide open when the mower is not running and, as near as I can tell, there is no movement of the governor linkage to retard the throttle at any time when the mower is running. There is no manual throttle control, but you can move the throttle plate directly on the carburetor and the engine speed will vary, and if you fully close the throttle, the engine will stop. The spring is the one that came with the mower and seems to be connected correctly, but I have inserted a photo so you can confirm that or tell me what is incorrect.

I did try a few suggested things I found on-line, but I think the suggestions were based on the governor reacting, but not being effective. This does not seem to be the case in this instance, but I am not a small engine mechanic. Any ideas?

 

[Rivets]

This engine/carb is setup for constant throttle, which should be set at approximately 3200 RPMs. My instructions are based on the picture you posted. The vertical spring going from the throttle to the tab controls engine speed. To decrease engine speed, bend the tab up with a needle nose pliers. Bending it down will increase speed. What you are adjusting is spring tension vs governor tension.

 

[PK232]

I will give that a try in the AM. The thing that bothers me is that nothing should have changed and I doubt if the spring has increased in strength. That and the fact it didn't move to retard the throttle at all. Who knows. Perhaps I will get lucky.

 

[PK232]

This engine/carb is setup for constant throttle, which should be set at approximately 3200 RPMs. My instructions are based on the picture you posted. The vertical spring going from the throttle to the tab controls engine speed. To decrease engine speed, bend the tab up with a needle nose pliers. Bending it down will increase speed. What you are adjusting is spring tension vs governor tension.

I finally had a moment to look into your suggestion. What I found is that with the spring unattached at the anchor point, the spring still touched the anchor point with no tension on it. The anchor point is about 1/16 of inch thick so the spring is currently stretched when in place less than 1/16 of an inch. Based on that, my feeling is that bending the anchor point will only change the static position of the throttle and not affect how the governor responds. As a result I left everything as is.

It looks like there needs to be another reason, and all I can come up with is that something changed inside the case. Considering the age of the mower, I will probably go with a new mower at some point rather than disassemble an old one to that extent. I only use it in areas where a riding mower doesn’t do the best of jobs so I can wait for until prices and supplies tend to stabilize a bit. Thanks for your suggestion.

 

[bertsmobile1]

The Governor makes the engine go SLOW
The faster the engine spins the harder the governor pulls against that spring
The spring tries to hold the throttle open
So it is a tug-o-war between the governor & the spring.
I read through your post a couple of times but can not se what your problem is
When the engine is stationary the governor had done its job so it does not pull against the spring , thus the spring will be slack .

With the engine running full speed push the throttle open to increase the engine speed
If you feel the governor pushing back against your finger then it is working as it should
Be careful where you put our other hand when doing this because it is easy to end up with the mower over the top of your other hand OUCH !

 

[PK232]

I understand the purpose of the governor is to slow the engine. In this instance, since there is no manual (user) throttle control, it is meant to keep the engine at a constant speed regardless of the load, i.e., closing the throttle as needed when the blade is disengaged and opening the throttle as needed when cutting grass, always keeping the engine at a constant RPM.

The reason I posted was that it worked that way on my mower for eleven years but it s currently not doing that. The throttle is always wide open.

Rivets suggestion was based on the premise that this lack of movement by the governor to reduced the engine speed was the result of too much spring pressure and that it could be corrected by reducing the spring tension. He suggested by moving the anchor, it would reduce the stretch of the spring and therefore reduce the spring pressure. My reply indicated that in this case, it would not reduce the pressure because the spring was not really being stretched at all. The problem is not that the spring is creating to much pressure, the problem is that the governor does not appear to be creating any force at all.

 

[sgkent]

Are you saying that the engine runs too fast and over speeds?

I don't know but that might be an engine with an air vane that controls the RPM. If so you can check it this way but without removing it.

 

[PK232]

Yes, it runs too fast.

That air vane is associated with the automatic choke, not the governor. I have watched mine work and it works correctly.

Thanks though for the suggestion.

 

[bertsmobile1]

I understand the purpose of the governor is to slow the engine. In this instance, since there is no manual (user) throttle control, it is meant to keep the engine at a constant speed regardless of the load, i.e., closing the throttle as needed when the blade is disengaged and opening the throttle as needed when cutting grass, always keeping the engine at a constant RPM.

The reason I posted was that it worked that way on my mower for eleven years but it s currently not doing that. The throttle is always wide open.

Rivets suggestion was based on the premise that this lack of movement by the governor to reduced the engine speed was the result of too much spring pressure and that it could be corrected by reducing the spring tension. He suggested by moving the anchor, it would reduce the stretch of the spring and therefore reduce the spring pressure. My reply indicated that in this case, it would not reduce the pressure because the spring was not really being stretched at all. The problem is not that the spring is creating to much pressure, the problem is that the governor does not appear to be creating any force at all.

So now we are getting somewhere
Either one of two things have happened
1) the governor has slipped on the shaft ( if your mower has an internal governor )
2) the governor is not working
If it is an airvane governor, some thing is preventing it from moving to close down the throttle
If it has a mechanical governor then it has fallen apart & requires replacing

 

[sgkent]

Yes, it runs too fast.

That air vane is associated with the automatic choke, not the governor. I have watched mine work and it works correctly.

Thanks though for the suggestion.

it can't work correctly or it would slow the engine down to the proper RPM. The throttle spring pulls the throttle open to make the engine go as fast as it can, and the governor then slows it back down to the proper RPM. The two battle between each other. If the governor physically works then the link or spring between it and the throttle has failed, or something has come loose.