4.0L fuel pressure issue?

RenegadeT

RenegadeT

no shirt,no shoes,no dice
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Joined
Mar 24, 2005
Location
Stokesdale-Greensboro
I fired up my 90 XJ Renix 4.0L, idled for a few minutes, then drove it to a differnt place in the driveway. 10 minutes later, I fired it up, it wouldnt stay running, would shut off after 2-4 seconds. Hooked up the fuel pressure gauge, and it showed a strong 39 psi at startup, but quickly dropped off to zero as it died. Blipping the throttle does nothing to get fuel flowing. Any ideas what to check/sweap/adjust? It was idling fine before, but it was running rich or missing under even a slight load.
I thought there was supposed to be 31psi, then 39psi with the vacuum line to the fuel pressure regulator disconnected. Is it maybe FPR supposed to be wide open at startup, then something electronic tells the FPR to kick down to 31psi, that's where my problem lies?
 
I was gonna say only time i lost any pressure on my 4.0 was when is had a baseball size hole in the block, glad it was something easy!!!
 
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