Goped problems

I just recently bought a goped sport and I rode it today and when I tried to accelerate it just boggs out and doesnt want to accelerate it the primer doesnt fill all the way by the way it's just literally half way filled the goped is fine and runs and starts right up I just need help on what this could be somebody please help me? Thanks..I really appreciate it...☺ btw wasnt sure if this was the best place to post this

What's a "primer"?

If acceleration is poor, it usually means the controller can't put enough current into the motor, either because the battery sags in voltage too much (eitehr because it's made for low current use and can't handle the high current, or because it's defective or not fully charged, etc), or because the controller's current limit is too low (which is usually to protect the motor against overheating).