Sounds like you have the manual, so go to page 17 and set the low and high screws to what it says to. Follow the steps on the following page to get it set correct for your elevation, operating environment. I run these pumps on mile long hose lays and it is all about how well you can adjust the carb. Also run 24:1 in them as I'm sure you don't have the new $7k Watson that runs on 50:1.
I've checked the mixture screws.. As per the manual, 1 turn out from seated. Although they weren't exactly 1 turn out, they were pretty close ( low a touch rich, high just a touch lean). I put them back adjusted as they were. Starting and warm up performance is fine, and, it takes throttle up without an issue. But, no matter what.. about 90 seconds to 120 seconds after going to full power, it just slowly dies. One thing that I haven't tried, is to tweak the high screw as it starts to die ( from running great, to stopped is about 15 to 20 seconds). Popping off the air filter and spraying fuel into it as it dies, is on the "to do" list. But, what has been tried, is squeezing the primer bulb as it dies.. That kills it immediately.
Then the whole crew runs over.. things get pushed. .. levers get moved.. starter gets yanked. again and again and again.. fuel line gets disconnected and reconnected... Finally, it stutters into life.. and the cycle repeats itself. The working definition of insanity, is repeating the same action, and expecting a different result
Yes, we can be a dysfunctional family.
Running environment ..500 ft. above sea level... 70F to 80 F. Hose lay of 50 or 100 ft.
The downloaded manual shows an original print date of 2015, and it is marked " Revision 2", which implies changes from original printing. As per the graphic .. it looks identical to our rather used unit.
As per the revised ( 2015 original, revised ver.2 manual)...
GASOLINE: 87 octane unleaded automotive gasoline (maximum 10% ethanol)
OIL: High quality two-cycle mixing oil with API-TC, JASO-FD and ISO-L-EGD certification (e.g., Amsoil Saber® Professional Synthetic)
FUEL MIX RATIO: 50:1 (gas to oil)
Note: Not enough emphasis can be placed on the use of correct gasoline and oil mixture. Using less than the recommended portion of oil will cause overheating and possible engine damage. Using more than the recommended proportion of oil will cause spark plug fouling, erratic carburetion, excessive exhaust smoke and rapid carbon deposits.
Could the revision(s) be that recommended use of premium synthetic oil was the reason for the 50 to 1 ratio recommendation?
In my Landscaping company, I had 2 LawnBoy mowers that were marked 32 to 1 .. I fed them 70 to 1, Pre3mium Ethanol free Premium, a splash of SeaFoam, mixed with Amsoil Saber, and they loved it. Bought used, and then I put hundreds of hours on them without issue. But, there's no way I would have tried that if I wasn't using a premium synthetic. Same mix that went into line trimmers, blowers, chainsaws. It was easy to just have 1 or 2 . 2 stroke cans, with identical mixes.
24 to 1 vs 50 to 1 is literally half the lubrication.. I can't see that there were changes in the engines that would only require half the lubrication. But then again, engine design, requirements of lubrications, etc., etc., aren't anything that I have any expertise in.