Intek V-Twin Governor Issue (is it dead?)

[bond-007]

Engine:
Briggs & Stratton Intek V-Twin model # 44S777-0011-G1 with about 100 hrs on it

Current problem:

• When I start the engine, it immediately wants to rev to full speed (and beyond)
• It seems to be operating as if it is ungoverned with throttle set to idle

History:

• This is after a carb rebuild to correct a varying engine speed under load
• Carb rebuild went as expected and seemed to fix that issue
• Factory manual suggests adjusting governor post rebuild and the maximum no-load speed appeared to be a few hundred RPM lower than specified
• I was adjusting the idle RPM and max no-load RPM (with digital tach) by bending the appropriate tabs per the service manual
• Everything seemed to be fine, so I wrapped up and pulled the mower into the garage

Troubleshooting:

• The next time I started it, it immediately decides to rev to full speed, so I shut it down
• Checked/adjusted static governor
• Bent the tabs back the way I found them as close as possible
• No difference
• I can force idle by holding the throttle closed but if I let go, it just goes to wide open throttle
• I have pulled the carb off to inspect and ensure the throttle plates are still attached, as I have read this as a potential issue for uncontrolled idle. They are still attached.

Questions:

• Is the in/out play shown in the video indicative of the governor having failed?
• What is the definitive testing/troubleshooting for governor operation (before going through removing the engine and tearing it down)?
• What am I supposed to feel if the governor IS intact and working/how it should react?
• Any other potential culprits to consider?

Video shows governor linkage with play inward and outward which I find troubling at the marked timestamp in description as well as general overview showing the governor linkages and operation

 

[Bellcrank]

https://www.thepowerportal.com/disp...pairManuals/272144VanguardTwinCylinderOHV.pdf . Section 5 for governor adjustment.

 

[bond-007]

Never got the notification email the thread was updated. Thanks for the comment.

44S777-0011-G1 is supposed to be manual # 273521, which I followed for the carb removal, rebuild, reassembly and static governor adjustment.

At this point in diagnosis, what I need, is some sort of procedure to tell me if the governor mechanism in the crankcase has failed. I believe that would be to disconnect the linkage from the throttle plate, manually control the throttle and observe if the lever arm moves with changing engine RPM.

If it doesn't move, then the governor mechanism has failed (and it isn't some other issue with air/fuel/spark)?

It just seems very unlikely that this mechanism would fail in 100 hrs of operation and even more mysterious as to how it was working fine up until the engine shut down and the next start it has totally failed.

 

[bond-007]

I just found this handy troubleshooting chart.

Trying to understand how/why they want the governor spring disconnected (which pulls the throttle open) in the previous step and then in the next step you move the throttle plate to WOT with the expected result of the engine returning to idle.

 

[bertsmobile1]

Yes , the flow chart is badly written.
The spring is removed so you can feel for binding / restrictions
It HAS to be replaced when the next test is done

 

[bond-007]

Well, this definitely explains my problems:

 

[Scrubcadet10]

Looks like it is time for a new governor gear P/N 793338
Once you get all of the old pieces out of the sump and block, i always use a magnetic tip tool, a good magnetized screwdriver should work, i run it around all inside it to be sure of getting any last piece of metal debris out. Granted they usually break into the big pieces you see, it's not worth it to not do it.