water pressure gauge hookup

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

Don't go there, goes into the bottom of the block look down in near the welch plug that has the serial number on it that's where the nipple screws in.

Thanks once again sir. I really do appreciate the help. It took me a minute to find it but I finally found it. Now I just have to find a hardware store that has them....Thanks again, Jon http://www.bassboatcentral.com/boardstuff2/beers.gif

Home Depot or Lowes usually will carry 'em.

Great, I have to swing by Home Depot tonight anyhow. Thanks, Jon