I have a 2000 johnson 225 ho that I installed a water pressure gauge on and it doesnt work right. I installed the water pressure gauge line in between the lines that go between the thermostat housings. This line is a 3/8" line. Should the pressure gauge work hooked up here? I started the motor on muffs and the gauge didnt seem to be working so I disconnected the line at the gauge and very little water was comming out. I then disconnected the line at the motor and very little water was comming out. What do you guys suggest? Thanks....Jon