can anyone explain internal workings of the fuel pressure regulator as i think mine is playing up and will be replacing with uprated one soon but wld like to understand how it works anyway.is it a valve that opens to release pressure on idle and closes on boost to increase pressure or vice versa.

 

Roughly put it's a valve that regulates how much fuel that will be returned to the tank (it sits inline after the fuel rails).

It's there to keep fuel preassure relative to manifold preassure (if ratio 1:1), at atmospheric you should have say 3 bars of fuel preassure, a 1 bar of boost you'd then have 4 bars of fuel pressure.

/J

 

thanks for reply.my atmo pressure and idle is 3.5bar and used to be 2.8 with standard pump 3.2 with walbro pump but i think pump is now overpowering the valve hence the upgrade on the way

 

Have your revs started plaing up at idle? I suspect mine has the same fault and the lambda is unable to go closed loop due the incresed fuelling.

MB

 

I would suspect your lamda is dodgy. My car can still run closed loop using 550's on a walbro at 3.4 bar atmo.(Std 95 ECU)
Sometimes the increased fuel press at atmo can actually improve the midrange pick up as they can be a bit weak there.

Andy

 

Thanks Andy,

Mine's a 99Uk with a tek 2.5

Mervyn at PE is looking at it tom. I had it on the select monitor and the lambda reading was high, but moving. It behaves fine once moving, but the engine cuts / nearly cuts when you come to a halt. The lambda is less than 6 months old. The MAF was dropping into -ve numbers trying to keep the revs down, then giving upand going to 0 (safe)

The theory was that the fuel pressure was too high at idle, and the the other gizmo's were trying to compensate, but couldn't go closed loop.

Will keep you posted. Might be a vac leak too.

MB