These small pumps don't put out much pressure, As long as you have steady fuel flow you should be good there.
What engine is on this machine..... Model AND Spec numbers ?
Try applying the choke just a little and see if the stumble goes away, If so the carb is running lean (partly restricted main jet) and needs a tear-down cleaning.....
Originally Posted by piston slapper
You never learn anything until you admit you don't know it all...
"Why go out preserved when you can go out beat up, worn out, sliding in sideways screaming, Holy Sh!t What A Ride" !!!