Cheap Pump

The two thick walled O-rings go behind the gauge and the back of the hose. If you forget to put them in, you get exactly what you describe. There are re-build videos on youtube and there was a thread around Xmas that linked everything.( oops, the thread wasn't here, it was a bargain gateway thread). Don't bother sending it back, as you need to disassemble all hand pumps and re-lube regularly to keep them working well. Search for rebuilding a chinese 4500 psi hand pump on YT.