HP 500 carb electrical and temp issues
 

What causes an alarm to sound sound on a marine engine, all gauges read normal but alarm is sounding,

For the alarm, there are only 3 things with senders that will set the alarm off. High Water temp, Low Oil pressure and Low drive lube. Disconnect each sensor one at a time when the alarm is sounding. The alarm sensors use a tan wire with blue stripe. If the alarm does not stop sounding when one of the sensors is unplugged, then the tan/blue wire has a short somewhere and is grounding out.