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I can't offer much feedback since I'm not familiar with Suzuki motorcycle fuel systems; and, have no access to a wiring diagram or service information for this fuel system.  Anything you can share in that regard will improve your chances of getting feedback.

Did you have the sample rate at 1M/s (sample interval at 1us)?  Adding two waveforms: voltage on power side and voltage on ground side... will help give us a better picture of the situation.  I don't like the sharpness of the top and bottom peaks either.  However, all commutator segments have sharp top and bottom peaks and their amplitude is not huge so I am inclined to ignore them as possibly normal for this pump motor.  What was the fuel pressure during this capture?

I would focus on duplicating the loss of power concern.  Interrogate the owner about length of ownership, service history, type of fuel, fuel additives, fuel age, refueling habits, driving habits, distance and time elapsed from starting engine to experience the symptom, etc.