Water inlet problem

[Pablo1]

I have a 2009 Coachman VIP 545/4, and, at the end of last year drained off the water system, and left the hot and cold drain taps in the open position. To be rady to start the season, I have been purifying the aquaroll, and then I usually pump this through the system, allow to stand overnight, then pump through clean water and away we go. I connected the pump, closed the drain taps, ensured the kitchen tap was open and switched on the pump (caravan connected to mains electric). Pump whirred, tap coughed, then nothing. Pump ran for several minutes ( enough to fill heater tank), but nothing through taps. Opened each drain tap in turn, and water runs out. Checked in aquaroll, and hardly any water has been used.
As water comes out of drain taps, I assume that pump is working ok, so am at a loss as to why water is not getting through to taps.
Anyone got any suggestions? All gratefully accepted and tried!!

 

[Damian]

Is your pump an inboard or drop in type?

 

[Pablo1]

Hi, Damian,
It's a drop in (Whale - I think) pump, one of the pistol release type. By the way, I don't fit filters into the Ultraflow housing.

 

[woodsieboy]

Hi Paul
We have 545/4 Pastiche, our pump is Truma Ultraflow with the pistol grip fitting,we have had a similar problem to the one you describe,and the pump light in the control panel would not always stay on. I traced it to lack of pressure in the system caused by the water filler pipe in the pistol grip not being a tight fit.I replaced the metal clip on the pipe with a jubilee clip that I could tighten and not had a problem since then.My other thought is that you must have a drop in pressure somewhere else in the system.As the pump has not pumped a lot of water out of the aquaroll but the pump has been running I would try a different pump and if you get the same result it points to water problem rather than 12v.