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Discussion Starter · #1 · (Edited)
I cant seem to find a write-up on how to replace the fuel pressure regulator on my 1997 540i (m62). It is not in the Bentley manual either. Does anyone know how to?

Background:
I recently did a fuel pressure test using the Bentley manual, here are the results which led me to want to replace FPR.

According to Bentley:
Connect to fuel delivery line in engine bay for both tests
All e39 vehicles: 50.76 ± 2.9 psi

System Pressure (pump only/engine off):
17psi
Residual Pressure:
engine on: 20psi
I then turned Off engine after idling for 1 minute and the pressure then dropped all the way to Zero in like 1.5 sec..

Bentley states if it does not maintain pressure to check for leaky injectors, fuel lines, and check fualty fuel pump check valve. I did not see no leak in either injectors nor lines. It states to test fuel pump check valve by squeezing fuel delivery line after engine shut off to see what happens. since no pressure was maintained it points the fault to be in the Fuel Pressure Regulator..

I also tried pressing the gas but the gauge would barley shake while staying at 20psi.
Also, the fuel pressure specifications seem very broad... would 5psi be as good as 50psi ???
Also, according to a thread to test FPR health your suppose to take off vacuum hose while engine running. The gauge should jump up to 10psi more. I saw no change at all.
The vacuum line was dry aswell. no moisture. so thats good I guess...
 

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fuel pressure is not very broad.. it should be at 50 with 5% drop when turned of and hold steady. your pressure of 20 is too low. and given the fact that it drops to zero is an indicator of leaky injectors or bad fpr. goto realoem and put in the last 7 of your vin to find out what type of system you run and where to find it. Most are next/with the fuel filter just under the drivers seat accessed from below the car.
 

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Discussion Starter · #3 · (Edited)
for sure ill order the o-rings and fpr. is there a proper way to take off? Besides my idea of depressurizing fuel lines, get small bucket n rags and try to yank it off lol? Its on the fuel rail btw
 

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nope just dont mix the lines up when you reassemble them..
 

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I wouldn't do the orings until after the fpr.. fprs fail MUCH more than the orings
 
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