ok guys i just installed ISSPRO gauges. the fuel pressure gauge was readin 10 at idle and about 7 when i would get on it. Now when i start it and idle it sits on the pin and doesnt budge, and when i get on it it rises to about 5 then never moves from there idle wide open nothing. Could the gauge have gone bad, or could it be a lift pump. I have a bd diesel lift pump on it for now. let me know what you all think thanks guys!

 

Hard to tell without puting a mechanical gauge on it.

 

We need some details here - how is it plumbed?? 1/4" line, 1/8" line?, isolater? Where are you taking the measurement from? Needle valve or pressure snubber?

Its always handy to have another pressure guage (any kind) that you can use to verify the operation of your incab gauge.