Check to make sure the little rubber o-rings are in good shape for each accelerator pump. They're the big ones in plain sight on each barrel. Operate the throttle by hand, and see if any fuel leaks around them. If they can't hold any pressure, the the accelerator pumps will shoot fuel out thru the o-ring instead of sending it to the engine.
Just a thought, as its something easy to check.

But really, your fuel level might not be right. Do a search or contact dapbmw on setting the float level properly. You have to do it by actually checking the level of the fuel in the carb, with a main jet removed, using a measuring stick in the top while the engine is idling. I can't remember the exact number. 40mm comes to mind, but thats just a guess and I could be way off.
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1974 2002, 4224479, #74 EP/FSP, daily driver, track toy
1983 Yamaha RX50: 7hp/70+ MPG, in town run-about
1992 Miata: #43 CSP, winter beater