X5 2001 no fuel pressure at motor

[Hi_reach]

Got a e53 4.4L that just stopped
Replaced fuel filter and fuel pump( symptoms pump couldn't supply enough fuel starved at on 4k rpm)
Getting 60psi at tank
Drove it home 20 k's now
No fuel pressure at motor again
Could it be blocked fuel line or regulator
Does the regulator require vacune to let fuel till the motor
Carnt get access to a hoist till next week to get panel off filter
Is the vac switch on front of block right side?
At Whit's end

[andrewwynn]

How much fuel in the tank? Most often the problem is the siphon jet leaking.

[Hi_reach]

Full

[andrewwynn]

You said 60psi @ pump but what flow rate? Measure at rail and observe when WOT. If drops it almost always means pump is at fault. Pump needs to supply >60 psi I think. It needs to send about 15-18psi back to the left tank plus 50 to engine. (at volume).

It points to the pump at fault.

[Hi_reach]

Sorry don't know wot means
Anyway 60psi don't know flow rate
I replaced fuel filter and drove it home it starved at high revs
So bought brand new pump
But nothing at engine no even dribble
Like it's blocked

[Hi_reach]

Hope to get to hoist this weekend and see if pressure is at filter. When reading I seen broken vac hose would cause no fuel?

[Hi_reach]

Originally Posted by andrewwynn

You said 60psi @ pump but what flow rate? Measure at rail and observe when WOT. If drops it almost always means pump is at fault. Pump needs to supply >60 psi I think. It needs to send about 15-18psi back to the left tank plus 50 to engine. (at volume).

It points to the pump at fault.

Thanks mate but got nothing at rail not even a dribble. Has brand new pump and filter. Would a bad pressure regulator stop fuel from getting to motor

[chedeng]

This is for my 2001 BMW X5 3.0 so I'm not sure if pump / filter are the same as on your car. I am just throwing this out your way to assist with your troubleshooting.

Did you replace just the pump or the whole assembly? This has happened to me after replacing the fuel filter/regulator. Somehow, the new fuel filter/regulator pressure was 100psi (measured at the fuel rail) where it should have been around 55psi. Obviously too much pressure and that caused the little white corrugated hose/tube in the fuel pump assembly to burst open thus pump can no longer supply fuel and it just circulates inside the tank. I replaced the whole pump assembly, returned the "bad" fuel filter/regulator for a new one and everything is good so far.

My educated guess is that hose may have a pinhole leak in that little hose so at high RPM, it can no longer supply proper flow rate.

Also, check to make sure fuel filter/regulator is installed correctly; in / out hoses are where they are supposed to be connected.


A note on the vacuum line connected to the fuel filter/regulator, at least on my car, it is only a "vent" and does not do anything at all. It seems vacuum is not really needed to modulate fuel delivery to the motor.


Keep us posted of your progress.

[andrewwynn]

X5 uses a FPR without a vacuum line. In, out, return. If pressure not regulated coming out it's possible the hoses are not correct.

Was the rail pressure correct after pump replacement then stopped working ?

FPR is almost never the problem it's almost always the pump.

You need to treat the problem from the current symptoms regardless of what parts have been replaced.

Do you still have the original FPR? The odds are nearly 100% the problem is either:
1) pump broken
2) fpr hooked up wrong
3) fpr briken

Most likely pump related like the example above split internal hose spraying gas back into the tank.

[bcredliner]

Are you saying the vehicle ran fine for 20K?