I have a Holley blue pump I went to the track and after my first run I noticed only 3 psi. When I got it home in the garage where I could hear it I heard the electric motor running and it it sounded like it was blowing air back into the tank.I think it's the check valve.Has anyone done a rebuild on these?

I have done one before.
I order the rebuild kit from a local hotrod shop. I think summit or Jegs may have the kit in stock.
It comes with an assortments of gaskets, some replacement fuel pump viens or blades(however you call it) and a regulator spring.

You can get the pump apart by unscrewing all of the screws on the bottom( watch out for those pump blades falling out), then separating the pump from the motor by unscrewing those long screws that goes through the motor to the body.
It's not that hard.
Have fun and check for leaks afterwards......

Yes they are pretty simple. Just order the rebuild kit and you'll be fine.