Testing fuel pressure

[acarr6]

What's the best way to test fuel line pressure on our cars? I know the non M have a valve on the fuel rail... any ideas? Was thinking I can pull off the LPF sensor. I just want to see if it holds pressure after I prime it, don't need to actually start the car.

[deansbimmer]

BMW's ISTA-D diagnostics software provides an ABL to read the system's fuel pressure- that's the normal method. If a faulty sensor is suspected and you need to cross reference the sensor's readings with a manual method then there is a special pressure gauge tool used at the sensor's location. That is the only location pressure readings would be able to be obtained.

[BPMSport]

Any OBD diag tool/reader with live data support should show this data.

[Compman]

What about if you're trying to see if the fuel pressure drops over night?

Once you turn the car ignition on the fuel pump will prime.

I'm hunting down a cold start issue and I want to see if my fuel pressure is dropping over night

[deansbimmer]

Then you'll have to install a mechanical gauge in the pipe. There is a special tool for this or many have fabricated an in-line Pressure gauge for connection there.

[active_m]

Originally Posted by deansbimmer

Then you'll have to install a mechanical gauge in the pipe. There is a special tool for this or many have fabricated an in-line Pressure gauge for connection there.

I'm currently tring to chase down a cold start issue myself and want to test fuel pressure with a mechanical gauge. Would you happen to know the part number for this special tool needed or where I can source it?