VR_Life

Ok so what's wrong with this picture :

1) Fuel Pump -> Pressure Gauge -> FPR -> Fuel Rail -> Injector

Shouldn't it be :

2) Fuel Pump -> FPR -> Pressure Gauge -> Fuel Rail -> Injector

Assuming Pump is running at a higher pressure than the FPR, then the pressure before the FPR, A) = Pump pressure, while the pressure after the regulator B) = actual Fuel Pressure (which is what I'm really after ... :-)

A) Not Equal B)
Correct setup is 2) ... right ?

Too many years & frazzled brain cells, forgot all my undergrad physics, help me close an argument - thanks

Pop3

you need to see the pressure for the injectors so I'd say 2)

Jeff Vader - boscoj

they both provide valuable but different information. edit I think I just proved myself wrong . . .

Thomas_A

On most injected cars, the FPR is on the return line to create the pressure upstream.

Pump -> Gauge -> Rail -> Injectors -> Return -> FPR -> Return to tank

Jeff Vader - boscoj

and while I'm not 100% sure how these things really work I think there is a fundamental difference in FPR operation on turbocharged systems.

So I guess there is only a need for one guage, so I guess my previous post is wrong.

I found this picture in a document I have . . .

<img src="http://66.134.70.69/files/audi/fuel_system.jpg">

VR_Life

Can't imagine what's valuable except pressure at Injectors ... but hey, I'll bite ... what's is it ?

VR_Life

So the gauge does need to be after Fuel Pump / Filter and before the FPR !

VR_Life

So gauge between 3 &amp; 4 on your dia - looks like I lose the argument ;-)

Jeff Vader - boscoj

well I was assuming the post FPR pressure would be injector pressure. I guess not . . .

Jason @ Streetwerke

FPR regulates return leg back to tank, which regulates rail pressure in effect.