i can't get my water puppy to prime

having trouble getting my water puppy to pull water. i can't even get it to empty a full sac. i've attached a diagram of my setup. i tried to get the elevation fairly accurate so can get a good depiction of the flow and gravity impact. could it be that i need a new impeller?
thanks for your help!

How long have you been using it? They suggest to change the impellar after 500 hours. If you ran it dry, that number would be less.

I am currently using a 1140GPH self-priming pump. It uses a bronze impellar, yet still pulls a suction.

i think that this is the original pump, so it is probably at 780 hours. visually it looks okay, but maybe it is too flexible or there might be a slight wear spot that causes it to let a little air come through, thus not creating enough suction to pull the water up?

I have the same pumps and you need to change the impellar every 1 - 2 years. The original black rubber impellers dry rot and do not pull very well.

get yellow ones from a MC dealer, they work better than the old black ones

someone got the part number on those yellow impellers? I need to order a couple more.

Probably the impeller especially after a winter lay-up. You may also want to make sure the check valve is not sticking closed.

replace the impeller, it's quick and easy and is probably the issue.

changed the impeller and am still having problems. i actually think the problem lies within the design of the system. i do not have a check valve between the pump and the Exit thru hull, which is allowing the pump to suck air instead of water. hopefully this will be the cure!

Check it by dumping water down the exit thru hull. Your exit should be above the pump. My bet is you created an air lock in the system or the existing check valve is stuck. Tap on your check valve while running the pump.

The check valve between the pump and exit should not be necessary. You would place a check valve in this location if you did not want liquid to flow back into the line.

If none of that works, you have had a mouse nesting in the line over the winter.

How about the obvious, if you would ever admit it, is you intake valve open?

there is no intake valve.
from reading the description of the jabsco water puppy, it says that it needs to be air tight in order to self prime. my other two pumps both have the check valves between the Exit and pump (there were on when i bought the boat)...i just figured the same as you...unnecessary. but after reading the product description and thinking about it...it might be the cause.?

and i am certain the check valve between intake and pump is on in the right direction

Those aerator type pumps bleed water slowly back through the impeller when they aren't going, so a check valve between the pump and the thru hull keeps the ballast in the sacs. Either side of the pump would work though.

Have you checked the voltage you are getting at the pump? Is the pump running in both directions? If it sounds like it's running it's probably getting enough power but still might be worth checking.

It should prime OK with a full sac above it, apparently those pumps are supposed to prime up to 3 feet above the water line.

One thing I was told when our pump (Ballast Puppy) stopped working was that the impeller can get stuck after a long lay up period, so (if you don't change the impeller) you could stick some dish washing liquid or Vaseline in there to make sure it isn't sticking to the housing.

(Message edited by jtnz on April 15, 2008)

(Message edited by jtnz on April 15, 2008)