If you're measuring on the nozzle side of the metering valve, you'll see "0" at idle on a gauge.
On the pump side, it'll be in the 10-15 PSI at idle depending on how many PSI your main check valve is set at and typically, a main would be 1-2 PSI on a naturally aspirated setup.
If you run a 5-10 PSI main check valve, not only will your leakdown percentage be artificially low, but the idle fuel pressure on the pump side will be more like 15-25 PSI.
Also, a secondary check valve (off your metering valve) could affect indicated idle fuel pressure. I typically set those about 18-20 PSI and that will limit things in the idle position.
Spud
