Fuel rail fitting size

[dray0151]

Wanted to check the fuel pressure on the fuel rail of my 04 F115 TLRC. Does anyone know off hand the size of the fitting on top of the fuel rail for that purpose. The service manual also does not state whether you should release the pressure on that fitting before installing the gauge fitting?

Also I assume with proper fitting an automotive fuel pressure gauge will work?

[fairdeal]

not sure about your specific model -

if you have a Schraeder valve on the rail - that is standard, any "fuel injection test gauge" should screw on

[rodbolt17]

same size as the fitting on your bike tube or your car tire.