Timbtb
just how many "quarts" of water are in the piping of that tankless
Yes there is water in there, not 10 gallons, but there is water
try connecting an open hose to the output side of the water heater
a weak pump would trickle water at a slow rate and NOT cycle on off, because it would not build enough pressure for the pressure switch to open and shut off the pump
not a high enough flow rate for the the tankless to fire up
There IS a Restriction/Blockage someplace
could even be mineral deposits inside the tankless
