Hey fellas
The toilet won't bring IN any flush water...the joker valve is in the DISCHARGE fitting and the tank--and therefor the tank vent--is at end of the discharge line. So why would you think that either one would have anything to do with the toilet intake??
That TWO toilet pumps don't work indicates that the problem isn't in the toilet pump, but in the plumbing. If there's a vented loop (anti-siphon device) in the intake, it needs to be between the pump and the bowl. If it was installed in the intake line between the thru-hull and the pump, it would pull in air, preventing the pump from priming.
Or, the first pump may have the problem Vic outlined and the second pump is defective. IMO, you have the best excuse anyone could ask for to return the second pump and upgrade to the Raritan PHC ...check that out here:
sbo.com PHII PHC LBA