Sink waterpump..

[Retro82]

Good morning everyone, having a problem getting a new waterpump to pump water from the tank in the back of my van . I've checked the small push switch byte fridge with a multimeter works fine and checked there's current at the end of the wires where it connects to the pump, so I thought it must be the pump so ve bought a new one.. No new one doesn't pump either! Can't understand it please help

[ghost123uk]

I've checked the small push switch byte fridge with a multimeter works fine and checked there's current at the end of the wires where it connects to the pump,

There should only be voltage on one of the wires (obviously when the switch is "on").
Did you remove the wires at the pump to test for voltage ? (you should )
Did you "earth" the meters black probe onto some bare metal when testing for volts on the wires ?

One wire to the pump should be "live" with 12 volts (when the switch is "on").
The other wire from the pump should go to an earth point.
I would remove both wires from the pump, turn the switch "on" and check with your meter which wire to the pump is "live" . Then make a note of which wire it is and connect it to the pump. If you then temporarily "earth" the other connector on the pump it should run. If it does, you then simply need to trace the wire that normally goes to the terminal you just earthed, and make sure the end furthest away from the pump is connected to an earth point.

Takes longer to type and understand than to actually test and do

[AdrianC]

No new one doesn't pump either!

When you say "doesn't pump", do you mean that nothing's coming out of the tap, or that the pump's doing nothing?

Assuming you've got +12v and a good earth, as John describes, then the pump should whirr. If the pump's whirring, then it's trying to pump. Try sucking through the pipe from the tank, see if there's a blockage or a split in the pipe. If that's OK, then the pump might just need priming to help it suck.