The pumps operate with a PRESSURE pulse.-----A 2 nipple pump mounts directly over the pulse port !---All you need on those is a nipple ( pump cover ) for fuel in.----And 1 nipple for fuel out.----The 3 nipple pumps do not mount directly over the pulse port.----No such thing as 2 outputs on these...
When prop is off ,the motor behaves like it is in NEUTRAL even if it is in gear.----Sounds like motor is running on one cylinder,----Or blown head gasket.----Or shock absorber below water pump is binding.---All easy to check out in my opinion.
Inspect all wiring on this motor.----And test run with another tank and hose.------Test run with the timing light.-----In my opinion it should be easy to find the issue !!
Most outboards drain themselves.----If in normal running position .----If the passageways are not plugged by silt / seaweed.-----Make sure drain holes on gearcase are clear too.
Compression test values should be posted.-----Model # should be posted.-----There are 2 different 115 HP models in 1996 year.----But I think this is the 60 degree looper.
You have discovered the basic principle pf refrigeration.----When a liquid vaporizes it needs heat.-----It gets the heat from the metal around it.-----Parts will get cold.-----This is why aircraft have a " carburetor heat " system to prevent icing.
