I recently Installed a water pressure gauge. On a 1987 force 125. Used the 1/8 npt port on top of the cylinder head. At idle it's almost always zero. Climbs to about 6 psi while it's first running then after it's warm I only get between 2-4 psi even at WOT. But if I rev it in neutral I can get 10 to 15 psi. Is all this normal? Boat runs well and does not overheat. 110 degree thermostat water pumps good from pee holes. Anyone know normal pressures for this engine? Thanks for any help