Foot operated pump, won't now prime...?

[SteelCruiser]

Have 100 litre water tank">fresh water tank in keel.
Got dirty "floaties" ( white specks ).
Unbolted the 56 nuts, & took off inspection hatch.
Cleaned out and refilled.
.
Now the foot operated pump only pumps air.
Tried filling the hose with water ( with tap on top of tank closed ) and then quickly trying to open tap and get pumping.
That little bit of water comes out, but then still only air coming out?
Suggestions?

[tenchiki]

I'm gonna make a wild guess that you damaged the pickup tube when you cleaned out the tank, and now the tube has a leak, probably right at the top.