Problem with test of 1s system - advice required please

[Cret]

Hi guys

I've got a 1s system that I bought of my friend ages ago and am just trying to test it out now before I start drilling things on my car!

Now I know it worked fine when it was on his car but it was removed quite a while before I bought it from him.

I've hooked it all up on the bench but cannot get it to pump water.
I have primed the pump using a syringe) and water flows through the pump & out the other side when I push the plunger on the syringe so I know it has water in the pump.

The reservoir is above the pump.
The pump vibrates and makes noise so I believe it is 'trying' to pump water through it, but nothing comes out of the pipe. I know there is no restriction from the tank to the end of the outlet pipe because I can pressurise the tank and water flows through.

I have got the pump hooked up to a 13.8v 3-5amp mains power supply to test it.

Can anyone tell me what might be wrong? I'm dreading that the pump might have somehow gone faulty while it has not been used as I suspect it would cost me a fortune to get it fixed and I can't afford that.

Thanks in advance for any help

Jim