impreza fuel pressure
 

what controls fuel pressure to the fuel pressure regulator mine seems to drop off after first ignition on it idles but wont rev and fuel pressure drops off is it just the pump that controls this ive just replaced it with a new walbro and still no good wondering if I have a blockage cant find any leaks but the pressure on the gauge goes down steadily after initial ignition on.

The FPR is on the offside fuel rail. If you pull the vac line off of it I believe standard pressure at tickover will be about 3bar. I will wait for somebody to confirm that. If the pump is fine then maybe a blockage, dirty filter, duff FPR? Could also maybe be a leak somewhere you can't see? Like injector o rings. Can you smell fuel? Check in the bay under the car and at the exhaust.

exhaust does smell like its running rich ive replaced filter and fuel pressure regulator still no good theres no leaks under the car at all what symptoms will an injector o ring leaking give or whats the easiest way to test cheers

Maybe get a garage to check the system holds pressure? If a seal is leaking you will loose fuel pressure as the fuel passes by the injector and just pours into the cylinder. This obviously wouldn't be good as it will destroy your oil and wash the bore. If it gets really bad the cylinder will fill with fuel and hydrolock. It your oil normal? Does it smell of fuel?

As well as an o ring you could have an injector stuck open?

This is all guess work from reading stuff on here and the web so I may be wrong. I am sure some experts will answer at some point.