Anyone know what the fuel pressure should be when the car is running.

I know that the fuel pressure is tested with the vacuum line disconnected but I just installed a digital gauge, and was wondering what the pressure should be with the vacuum line connected and under normal circumstances.
I just did a quick check with the vacuum line disconnected it was at 42.5PSI.

With the Vacuum line connected it went down to about 37.5PSI

What should I be aiming for as far as fuel pressure goes?

305 TPI Chev IROCZ.

 

Both of those numbers are right in the ballpark. With the vacuum line connected the pressure should drop a little(from the disconnected pressure) while the engine is idling. When you floor it the pressure should go up near the pressure you had when the line was disconnected.

 

Sweet thanks for the good info.