Getting live data from my Freestar shows Fuel System as OL-Fault. Open Loop I get that but what does Fault refer to? Is there trouble in the fuel supply, like bad pump or fuel pressure regulator? Interesting to note the PSI runs up like 78.4 during the fault , other times getting live data it runs without Fault and pressure is around 40 PSI, correlation perhaps?

 

There is nothing like getting bad info from a malfunctioning tool. When you get irrational or way out info from a tool there may be a compatibility issue between the tool and the vehicle.
The fuel pressure regulator may be located in the fuel pump module in the fuel tank. How about some info like , year, engine, and reason you are doing the checks.

 

It's a 2005 Freestar 4.2L Auto, keeps throwing a P0193 code. FRP sensor has been changed, vacuum lines appear fine. Trying to figure why the high pressure reading and inconsistent fuel pressure from live data.

 

Does your scan tool show desired fuel pressure and actual fuel pressure?
The reading compares fuel pressure to intake manifold vacuum not atmospheric pressure as a shop gauge would. Fuel trim info needs to be known to determine if there is a potential fuel pump problem. The sensor sends the info to the PCM which in turn determines the pulse width signal the fuel pump driver module will send to the pump assy. If you cannot access this info a different scan tool will be required in order to get that info so we know where to go next.

 

My scan tool (Innova 3040) shows the actual FP, not desired FP. Tried to find it from several sources online to no avail, one recent source claims 35-70 PSI. Either get a reading of mid 40's to the usual 78 PSI. Fuel trims on B1 hover around 5% and vary according to terrain and speed, while B2 generally falls into - 20% range to highs of -30%. These are the STFT . Could these indicate trouble in the fuel pump, as well as Oxygen sensor in B2? Or more likely a difficulty with injector issues on B2
Thanks for your help and input on these

 

It isn't a tool malfunction or bad information. When the ECU/PCM tries to go into closed loop but can't (for any number of reasons) then it gets reverts to open loop due to the fault. Hence open loop fault.

I bet that the ECU/PCM doesn't allow closed loop if the fuel pressure is not at the expected value (which might include an intermittent type issue like a dodgy connector, slowly failing sensor, or even intermittent fuel pressure issues).

I'd start with having an assistant drive and monitoring the fuel pressure as you drive. Check the factory service manual in the recent post to see if it has the proper fuel pressure.