I bought part number 3-4406. I can't get a boost reading or vacuum reading unless I physically blow or suck on the sensor as HARD as I can. I have the sensor mounted right to the outlet on the compressor housing with no readings. I used a multimeter to check the sensor. At zero boost according to my gauge (sitting in free air) the voltage reads 3.63, according to the reference table for my 50 psia sensor 3.63 volts=about 25 psi but I am getting zero on the gauge. When I blow into it with my mouth I can get 1 pound of boost but voltage goes down, that makes no sense since voltage needs to increase to make the display show boost although the display does show 1 psi. When I suck on it voltage goes up but the display reads vacuum. I take it my pressure sender is faulty or what? Please help, I have been pulling my hair out for hours now, Thank you.

 

 

Try tapping in to the fuel pressure regulator hose for your boost source.
This is the most used location.
I have the same gauge and never had problems with it.

 

x2 or off the intake manifold

 

Either or should work. Mine is off the Im though.