Originally Posted by oaseeker
.. I'm just surprised they didn't incorporate some type of warning system other that power loss (like a buzzer or something).
DT55 usually has a 'Water' warning system, activated by a float switch in the cylinder head, but yours may have been removed if it has a water pressure gauge? When the water jacket fills, this float rises and switches off the warning light and buzzer. If this system is working ok, then the red 'water' light in the monitor gauge will show and the buzzer will sound when the ignition is switched on, but the engine not running. Lower than normal water pressure would be acceptable to this system, if there is sufficient flow/pressure to fill the block/head and activate the float switch. If the pressure/flow is insufficient and the float switch activates, then the motor will go into 'guardian' mode and restrict itself to around 3000RPM.
BTW, sounds like your impeller needs changing