GRT Avionics

I have an EIS4000 with the GRT fuel pressure sensor. O-360-A1A with an Airflow Performance Fuel injection system.
When I power up the EIS it is reading 7-9 PSI before I turn on the fuel pump. When I turn on the fuel pump it appears to read normally in the 30's. Not sure what is cause the erroneous reading.

Although it did just strike my the the Airflow Performance has a fuel cutoff that is used to shutdown the engine. I also turn the fuel selector off at shutdown. Could there just be residual pressure in the system? Open for any suggestions.

Could be left over pressure. When you first installed the system with no fuel in the lines what did the pressure read?

It read zero. Next time I am out there I will open the bypass and fuel selector so pressure can flow back through the system and see what it does. Thanks.

My oil and fuel pres vdo senders both do this, but appear normal when running. Possibly the diaphram/spring/lever/potentiometer thingy is sticking inside.