diesel hand pump
I had to disassemble the pump first, the check valves at the input and output were wrongly positioned. In between was a kinked paper seal. It looked as if someone had just thrown the innards in there and screwed on. In fact, the hose connection on the output side does not quite fit into the thread. The thread on the hose connection is too long and must be turned off. If it is simply tightened by force until it fits, the valve diaphragm will inevitably be crushed at the outlet! Maybe the pump works a bit with just the input membrane, but I will not try it.