Briggs 31R headache...

Ok so most everything mechanical sounds like it's working as normal.

Dump the gas and try some fresh E-0 unleaded juice.

Wonder if someone, has been in the carb with a welding torch tip cleaner enlarging the main jet/s?

Choke staying wide open once warm?
Look the fuel is fresh and I am the only one been in the carb. And yes the dang choke is fully open. Also main nozzle/jet and air bleed jet have been remove and make they are clean.
Carb float height excessive?
No; unless, you call dead level [parallel to carb body] excessive.

BTW the needle tip has no wear. And it takes a pin punch to even get the pin out. As that is how I got to the needle and seat. Pressure test of 10 psi held over 30 minutes. No fuel in the plastic float.

might as well give these numbers before someone complains.
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Well its not the muffler, ordering a few crankcase gaskets so I check the internals. Maybe it is the ACR or loose cam lobe. Got to be something I am missing. The last I open one these engines was back in 2024; hence, why I don't the gasket.

The darn thing is actual shooting a flame out the carb at times.
 
Coil kill wire diode gone/going bad? Unplug the coil ground lead to see if problem still exist.
Been there Done that.

I just calling it and returning the mower and the customer's money then writing off all the parts used in the troubleshooting. No point keep throwing parts at it per say. First engine in 18 yrs that out did me and I have had some bad problem makers over the years.
 
Been there Done that.

I just calling it and returning the mower and the customer's money then writing off all the parts used in the troubleshooting. No point keep throwing parts at it per say. First engine in 18 yrs that out did me and I have had some bad problem makers over the years.
I agree with you. Let the customer have it back. Time to throw In the towel, due to time and parts wise.

Appears maybe?? it could be the WIMPY cam area needs inspected and if found suspect as we know not worth time and money installing a WIMPY new cam in those series engines.

Might tell the customer if you see a good replacement engine or complete replacement mower you will let him know.

If the engine were mine I might eventually check the cam, especially the WIMPY comp release area??,but I have some donor engines for parts. I've seen them cams do some weird things, but usually not as erratic and intermittent as you are seeing.
 
I agree with you. Let the customer have it back. Time to throw In the towel, due to time and parts wise.

Appears maybe?? it could be the WIMPY cam area needs inspected and if found suspect as we know not worth time and money installing a WIMPY new cam in those series engines.

Might tell the customer if you see a good replacement engine or complete replacement mower you will let him know.

If the engine were mine I might eventually check the cam, especially the WIMPY comp release area??,but I have some donor engines for parts. I've seen them cams do some weird things, but usually not as erratic and intermittent as you are seeing.
Although it is very frustrating and a huge waste of labor time, about once or twice a year I get one I can not figure out. I charge for parts and a substantially discounted labor rate. You can’t win them all. The equipment keeps coming in and going out, and the piece of equipment you can’t figure out remains. Sometimes for months and you keep going back and can’t get it. Extremely disappointing, frustrating, and big time waster and stress raiser.
 
Have you tried recutting the valves and seats, or at least relapping the valves. When doing so I would also running a valve guide reamer through both guides to make sure they are both in specs.
 
Been there Done that.

I just calling it and returning the mower and the customer's money then writing off all the parts used in the troubleshooting. No point keep throwing parts at it per say. First engine in 18 yrs that out did me and I have had some bad problem makers over the years.
Hi Star Tech,

Sticky intake valves in the guides? Similar problem like the Kohler twin I'm dealing with right now?

Just a thought.
 
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