Sounds like a regulator problem for sure, if it has too much fuel and fires off without the pump.
Live dangerously and take a chance on this. Or you could just drop in a new assembly Some people I know will reverse the leads to a fuel pump to try to free things up, I'm just not sure that this would help you with a regulator. 10 PSI of air backwards through the regulator???
https://www.bikebandit.com/oem-parts/2006-suzuki-boulevard-m109r-vzr1800-fuel-pump/o/m147607sch520453