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Discussion Starter #1
Hello, I own a BMW e46 330i from 09/2000. I recently went to change the fuel filter and notice the vacuum hose running up to my car was loose. I tried looking up possible connection points for it but they have other hoses on them. If anyone can tell me where the line is meant to go that would be great (video/images are also appreciated.)
 

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Goes on the "F" connector which is on the rubber air intake bellows rear of air cleaner . Beside DISA valve.
 

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Discussion Starter #5
Goes on the "F" connector which is on the rubber air intake bellows rear of air cleaner . Beside DISA valve.
I checked that area and it has a hose that connect to the engine unless that hose isn't meant to be there?
 

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Does the hose line connect directly to the fuel filter
The "hose" is actually only hose at the ends. There is a small plastic tube that runs the majority of the distance. Hose is used to connect the tube to the pressure regulator on the filter and to the previously shown lower port on the F connector.

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Hello, I own a BMW e46 330i from 09/2000. I recently went to change the fuel filter and notice the vacuum hose running up to my car was loose. I tried looking up possible connection points for it but they have other hoses on them. If anyone can tell me where the line is meant to go that would be great (video/images are also appreciated.)
There is only one line with a rubber hose at each end. Goes to F connector at the top of the upper intake boot. It controls the fuel regulator so loose is not good. Measure the filter nipple and get the right size hose . The orange hose in the engine bay picture.
 

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the people’s mod
2004 330Ci 115k miles
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Just FYI, that hose does not have vacuum and does not control the fuel pressure regulator.
Vacuum is after the throttle body and the F connector is before.
It’s just an air vent line.
 

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the people’s mod
2004 330Ci 115k miles
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Out of curiosity, where is the air coming from?
There is none.
The fuel pressure regulator needs an ambient air reference and BMW chose to have it filtered.
Also, if the diaphragm ever ruptures the leaking fuel/vapor would go into the intake (safety, emissions, etc.)

The DISA vacuum diaphragm has a similar port that vents to atmosphere.
 

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Just FYI, that hose does not have vacuum and does not control the fuel pressure regulator.
Vacuum is after the throttle body and the F connector is before.
It’s just an air vent line.
You sure about that? I have never traced it from top to bottom but I reached my conclusion
about the F connector because the tube at the filter end is a hard plastic with a short length
of rubber hose attached and the only like tube I can see at the top is the one where I indicated.
Also had the TB off twice and don't recall any hoses being attached to it. If there were an
open port there my trims would be huge. They're not. They are close to zero. I can't
see a hose attached to the TB on RealOEM either. So where on the TB is the FR tube
attached? I wouldn't mind taking a look at it.
 

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Is there vacuum at the F Connector, yes. Albeit minimal at best. Because it's in front of the throttle plate and not in the intake tract.
BMW used to have fuel enrichment (Ever since Bosch L Jet fuel injection) provided by vacuum connected to the then LARGE fuel pressure regulator. On tip in of the throttle, some injection enrichment was needed. By the loss of vacuum (connected to the intake tract at the time) acting on the then large FPR and it's large diaphragm the fuel pressure saw a momentary rise in pressure of about .5 Bar. This added in the extra fuel needed for smooth acceleration.

Fast forward some 4 generations of Motronic and all of the fuel enrichment is handled through widening the injector pulse. Much more precise and such is needed for better control of tailpipe emissions. An advance over the rather crude system of years ago.

Furthermore the very small diaphragm of the newer FPR would need a VERY STRONG vacuum source to have much of an effect upon it.
The hose is provided as a safety path in the event of a rupture of the diaphragm any fuel passing through would be sent into the intake.
 

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Discussion Starter #16
There is only one line with a rubber hose at each end. Goes to F connector at the top of the upper intake boot. It controls the fuel regulator so loose is not good. Measure the filter nipple and get the right size hose . The orange hose in the engine bay picture.
Thank you for that but now that only opens open more question. Mainly there are two hoses in the image with the small hose connect on the F plug and the hose that connects to the fuel filter down next to intake should i swap out the hoses?
925236
 

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There is none.
The fuel pressure regulator needs an ambient air reference and BMW chose to have it filtered.
Also, if the diaphragm ever ruptures the leaking fuel/vapor would go into the intake (safety, emissions, etc.)

The DISA vacuum diaphragm has a similar port that vents to atmosphere.
So my Covid addled brain thinks that it is vaccum that pulls air through the air filter and down the intake boot once the throttle plate is opened. What am I missing?
 

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Thank you for that but now that only opens open more question. Mainly there are two hoses in the image with the small hose connect on the F plug and the hose that connects to the fuel filter down next to intake should i swap out the hoses? View attachment 925236
I have just being tcontracdicted by others on here that the bottom one I indicated is nothing to do with the fuel regulator so I am just waiting for them to clarify the situation. I always thought it was for reasons explained above and from other threads on this forum.

 

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I have just being tcontracdicted by others on here that the bottom one I indicated is nothing to do with the fuel regulator so I am just waiting for them to clarify the situation. I always thought it was for reasons explained above and from other threads on this forum.

I don't think there is any dispute that the lower f-connector hose runs to the fuel filter. I think the only commentary is whether it functions as vacuum or not. BaliDawg was just indicating that the Disa has a valve but it does not have a hose.
 
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