I just got a Sunpro vacuum gauge for my 97 ram 1500 and it started at 0 when the truck was off and once the ignition turned on for the first time it jumped to about 20 while the car was idling. But when i tapped on the gas the needle stayed where it was, i drove down the street at varying speeds including full throttle and the needle never really moved more than +/- 2 units. Im pretty sure it is supposed to be jumping all over as I hit the gas but it isnt. Am I tapped into the wrong vacuum line? also my check engine light has been on for a while with a p0441 error code, maybe that could be causing the problem? Also even when the ignition turns off the needle stays on about 20.

Ill attach a pic of the line I tapped into in case it does happen to be the wrong one. The hose is the clear/blueish one to the upper right.

 

You're on the wrong side of a check valve there. Follow that line back toward the manifold and you'll find the one that's biting you.

 

You want to tap into a line that has (intake) manifold vacuum. I can't tell from your photo which line you've tapped into. If you have selected a good line and the gauge reads poorly or low, it probably means you have leaks somewhere (eg throttle body to manifold gasket, the vacuum fittings or lines themselves, possibly bad gauge, etc).

The check engine light isn't really important as far as getting the gauge to work properly since if your manifold vacuum was really as bad as the gauge is reading, the truck would be running very poorly, and you'd notice. However one of the possible causes of that error is a bad vacuum line. See http://www.obd-codes.com/p0441

 

So anywhere between that point and the manifold with a T-piece will work? I was told that just tapping into an open port that was plugged off would work.

 

As UnregisteredUser, you're likely tapped into a vacuum line with a check valve, which the whole point of is to trap vacuum for the HVAC and cruise control.

 

Yes indeed, an port that is currently plugged is the best place. In that line you're presently tapped into, if you follow it back toward the manifold you'll see a little plastic dude about as big as three stacked quarters in the line -- that's the check valve that's causing the gauge to stay high. Get your tee between that and the manifold, or into some unused port, and you'll be golden.