Vacuum gauge inop

[Francisco]

While doing a run up, I noticed the Vacuum gauge was not working it was CAVU, and I wanted to make sure the giros where ok - they are. So what can cause the gauge to stop working?

Also the Rear engine Fuel Pressure ( Fuel Flow) middle in the dual gauge is not working. We replaced the Mechanical fuel pump during the annual and the pump works find any suggestions?



Any help is appreciated

Francisco