I have been having trouble with my Jabsco Waterpuppys(model 18220-2121). They are designed to create a vacuum that will pull in water up the intake. Because of this, the rubber impeller is very tight in the housing and sometimes hangs in one direction when I try to change the direction (IE- Fill vs. Empty). I put a little grease on the outside walls or housing where the impeller sits. This solved the problem. Will a petroleum based grease eat the rubber impeller. What other grease can I use that won't damage the impeller, or is the petroleum OK?
I always run the pump in the reverse direction for a second after filling/emptying so that it is ready to go in the next cycle. That way it does not have to reverse while dry. Completly solved my problem.
A higher guage wire will probably solve your problem for good. I had the same issue with the jabsco pumps in my mastercraft. I would re-lube them with silicon and they would be fixed for a few weeks. When it was re-wired with 8 guage wire, it was fixed for good. These pumps pull over 10 amps and if you are running 12 or 14 guage more than a few feet, there will be a voltage drop.
Not only have I had the same problems with my water puppy, but my impeller has a plastic hub, which is now stripped. Now I can take the cover off, turn on the pump and watch the shaft spin and the impeller stay stationary!
The Jabsco ballast puppy has the same size impeller, but has a brass sleeve so the motor shaft can't slip. I'll get you the part number if you can't find it. You can buy the replacement impellers from depcopumps.com We can't sell parts or pumps unless they are for someone who bought a system from us per our deal with Jabsco.