Waterpump stopped sucking during winterizing

[bdaball]

I have winterized my coach a number of times. Both air and antifreeze methods. Here is my delema today:
I started the antifreeze process just like always. Very sumple method on the Newmar. Close the hot water tank by pass and change the suction by-pass valve from the tanks to the clear suction winterize line that is inserted into the gallon jugs of antifreeze. Turn the pump on and one by one open the faucets and wait for the pink stuff. When done I usually open all the valves to releave the pressure. THIS time I got three quaters of the way through the coach and the pump stopped sucking up from the antifreeze jugs. Pump would continue to run but not suck. That was evident by watching the clear suction line drain back down. Funny thing though is if you opened up the outdoor faucet valve to test the system the pump would start sucking again. Close the outside faucet and it would stop sucking but continue to run. You can watch it start and stop in the clear suction line.

I removed the pump, hooked it up to a 12v source in the kitchen sink and it would pump extremly well. Thought it migh have been plugged so I put it back in the coach and same thing. Runs but will not suck up the antifreeze. Open the outdoor faucet and it starts sucking although not agressively like when I removed it from the coach. If you loosen the pressure side line from the pump air pressure is released as if it was pumping air. If you open an inside faucet a mixture of mostly air is release with some antifreeze. Almost acts like my water pump has turned into an air pump.

System was fine on last trip of the season. We used tank water and outside source both. Pump is a Aqua-jet 5.3gpm. No visible leaks in plumbing system.

Any ideas?

[bdaball]

I have winterized my coach a number of times. Both air and antifreeze methods. Here is my delema today:
I started the antifreeze process just like always. Very sumple method on the Newmar. Close the hot water tank by pass and change the suction by-pass valve from the tanks to the clear suction winterize line that is inserted into the gallon jugs of antifreeze. Turn the pump on and one by one open the faucets and wait for the pink stuff. When done I usually open all the valves to releave the pressure. THIS time I got three quaters of the way through the coach and the pump stopped sucking up from the antifreeze jugs. Pump would continue to run but not suck. That was evident by watching the clear suction line drain back down. Funny thing though is if you opened up the outdoor faucet valve to test the system the pump would start sucking again. Close the outside faucet and it would stop sucking but continue to run. You can watch it start and stop in the clear suction line.

I removed the pump, hooked it up to a 12v source in the kitchen sink and it would pump extremly well. Thought it migh have been plugged so I put it back in the coach and same thing. Runs but will not suck up the antifreeze. Open the outdoor faucet and it starts sucking although not agressively like when I removed it from the coach. If you loosen the pressure side line from the pump air pressure is released as if it was pumping air. If you open an inside faucet a mixture of mostly air is release with some antifreeze. Almost acts like my water pump has turned into an air pump.

System was fine on last trip of the season. We used tank water and outside source both. Pump is a Aqua-jet 5.3gpm. No visible leaks in plumbing system.

Any ideas?

[Ray,IN]

My pump will do the same at times. Opening a faucet allows it to pump liquid. During the discovery phase of your same method, I found a water screen/filter on the outlet side of the pump was nearly clogged with clear plastic shavings. I couldn't see them until I dis-assembled the "filter" and closely inspected the fine screen wire. I'm assuming it was shavings from cutting openings in the water tank at installation. Funny thing is, the pump worked fine the first year of ownership.