I just installed Auto Meter electric fuel pressure gauge.
With key off gauge reads 2#'s,turn key on zero's out,start engine and gauge only reads 2#'s again.I checked grounds and power all good.I installed sending unit in place of schrader valve on fuel rail of Radix.I am thinking a defective sending unit since gauge zero's out like it is suppose to with key on.
Any thoughts?

 

The first autometer electric fp gauge I got was faulty but it was not 'reseting' like yours is. We had another gauge to test and confirm it was the gauge.

 

I had to cycle mine for like 10 times to have it read correctly. Air in the line? Mine works fine now and has for 2+ years.

 

When you say air in line do you mean in sending unit as electrical gauge has no line?

 

UPDATE: Problem fixed with new sending unit from Autometer.

Talked with tech from Autometer and he had me run a few test with multimeter.First test was red to black to confirm voltage,13.5 volts.
Second test was red & purple together was suppose to be 2.9 volts,but was only showing trace amounts of voltage.Third test was red to gray which was supposed to be .5 volts but registered 0. I faxed receipt to autometer and had a free replacement sending unit in 3 days.Hope this might help someone in a search someday.

 

Good deal!