As silly as this will sound, run down to bunnings (hopefully you aren't in Vic) and get a bottle of this
https://www.bunnings.com.au/mechanic-in-a-bottle-120ml_p0169259Sounds stupid - mechanic in a bottle. I hate snake oils as much as the next person, but once I find one that actually works, I recommend it.
I have soaked diaphragms in it neat and neither metering or fuel pump diaphragms hardened or were damaged (old ones became slightly more plyable but not perfect)
I had a badly gummed up talon trimmer carby - cleaned as well as I could. Would then run on choke, but not off (even idle - non adjustable carby). Tried some sort of liqui Moly carby clean additive - did nothing.
Drained fuel and put in this stuff and within 5 minutes it would run off choke and rev up reasonably (bit boggy still)
Just today, I suggested a friend get a bottle for his sanli which would only run well on choke, and would stutter and spontaneously stall at idle or part throttle.
He added a bit more than prescribed ml per L to the tank, shook back and forth - I listened over the phone as he started it and it started surging badly - told him to be patient. 3 minutes later it suddenly came to life - idle went smoother and up (he put idle up before to stop stalling). Would accept throttle fine.
Will this fix a carby that has sat for 10 years full of stale fuel - No. Will never replace a carby teardown, but it get rid of the stuff you can't reach
Peter Brock reckoned his energy polariser made a 'shi*house car good' - this additive makes a Shi*thouse carby passable, and reasonable ones better
Unfortunately, it won't help my 'new' ryobi chainsaw. Guy brought it over and straight up told me he was an idiot and grabbed the wrong fuel can. Piston not awful, but its not so good.
Edit - should also say I have no vested interests in the manufacturer (B3C fuel or something like that) or GA spares (who distribute it)