DIY : PTFE line- tank to HPFP + inline fuel filter upgrade

doublespaces

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Oct 18, 2016
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Is there any word on the difference between 1M and any other fuel rail version? Just curious if the drilled rail is necessary with a stock hpfp.
 

JuniorB

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May 9, 2017
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Here’s what I found, the small orfices are off the 535 car, the larger one off a 335.
8675C814-9A0E-412D-B21F-E3D2D97678F9.jpeg
5907DEDF-530C-4D94-87FC-DB4A4135AC98.jpeg
 
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Panzerfaust

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Jul 3, 2018
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So my apologies for the bump and stupid question, but I'll be done a short line replacement + HPFP filter removal in a day or two here.

How do you ensure you dont get fuel spray all over? Obviously when doing anything gas or oil line related its smart to have a rag on top and underneath to catch the excess, but what about built up pressure? Do you guys pull the fuse for the LPFP before doing this? Just let the car sit overnight? Or is there some form of check valve that I'm too blind to notice that will stop the car from giving me an ethanol bath?
 

doublespaces

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Unplug LPFP under passenger rear seat. Wait a day or so. Bring a rag.

Honestly I've never really had an issue but let pressure bleed off a bit first.
 

NoQuarter

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Nov 24, 2017
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Disconnect battery

Tap top of each injector with a wrench to remove pressure

Wrap a cloth over hpfp fuel fitting, release slowly.

On low side, same thing with the cloth. There is not a lot of volume once you catch the initial pressure release in the towel.
 

Jeffman

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Jan 7, 2017
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Better: pull out the fuse to the lpfp behind the glove box. Attempt to start the car. This will zero the pressure in the fuel line as the engine starts for 1 second and stops. You’ll get a code and dashboard error light, but this is easily cleared via MHD or scan tool. After doing this, disconnect the battery and resume your work.
 

Panzerfaust

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Jul 3, 2018
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Better: pull out the fuse to the lpfp behind the glove box. Attempt to start the car. This will zero the pressure in the fuel line as the engine starts for 1 second and stops. You’ll get a code and dashboard error light, but this is easily cleared via MHD or scan tool. After doing this, disconnect the battery and resume your work.
Thank you, unplugging the LPFP fuse and starting the car seemed like it'd be the best option but I wasnt 100% sure on unplugging the battery or not as I never have with any LPFP upgrades or when i did my BL coils (or anything else requiring me to run wiring for that matter) but I'll do it just to be safe since fuel and electricity isn't a fun combination.

Thanks guys, much appreciated! I may be doing a full write up of how I'll have my system set up if anyone is interested since I'll be doing a hybrid of different methods using parts I sourced from a few different vendors to save some cost that comes with N54 fueling upgrades when packaged together, and I plan on having everything in the engine bay rather than under the car for the other DIY'ers without access to a lift.
 
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JohnDaviz

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I have sucked in that thread and love it. Thank you for all the information.

A stupid question to make a circle on that DIY. I bought a rail and want to drill it to 4.5mm. Before i just drill in it :) How did you folks do it to ensure no particles remaining in the rail? And how far do i drill? Is there a specific stop? I don´t want to destroy my rail. Safety First :)
 

NoQuarter

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I have sucked in that thread and love it. Thank you for all the information.

A stupid question to make a circle on that DIY. I bought a rail and want to drill it to 4.5mm. Before i just drill in it :) How did you folks do it to ensure no particles remaining in the rail? And how far do i drill? Is there a specific stop? I don´t want to destroy my rail. Safety First :)

There is no specific stop. But I will say it is very easy to snap off such a small drill bit. I have a bit stuck in a rail right now and not sure how I will go about getting it out yet.
 

Blaster3500

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Nov 5, 2016
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Do you go with a bench drill?
Definitely remove the rail and the pressure sensor at the back. Once you are finished drilling flush it and blow with compressed air. The ID opens up shortly into the rail so you can't really do to far. It's pretty straightforward, take your time and it will be fine.
 
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seb.apprenti

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Nov 28, 2018
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Inspired by martymil’s post I decided to pull my HPFP filter, drill my fuel rail, add an inline filter and upgrade the line from the tank to the HPFP hard line. There are some gains by going straight to the HPFP but people are using a 1/8 npt adapter and the LPFP seals with an o-ring. Everyone says it works, but I decided to just leave the stock hard line. I was not a huge fan of pushloc hose so I looked into PTFE hose. It is much better suited for ethanol. The downside is that generally it is less flexible when compared to rubber hose. It was a tight fit especially for the fuel filter but overall turned out well. I chose to go with Racetronix hose and fittings because they offer quick connect PTFE hose ends. It makes for a clean install. This is a great option if you are just looking to upgrade the line from the tank to the HPFP or are looking to upgrade the line and add an ethanol sensor. Obviously the inline filter is optional when pulling the HPFP filter but I figure it is extra insurance. I do not have results yet due to breaking in a new clutch but will post up logs when I can. Based on martmils and others results it should help a bit on the high pressure side.

Parts list if adding an inline filter (If using an ethanol sensor you will need 2 additional $10 fittings) 7 feet will most likely work but 8 is a safer bet.

Fuel filter element- This was the smallest micron filter I was able to find that was rated for ethanol.

Parts list if just upgrading the line and adding an ethanol sensor- (remove the 2 6an-3/8 quick connect if just looking to upgrade the line)
Drilled fuel rail (11/64 or 3/16 drill bit) Before/After

HPFP filter removed

Mounting the fuel filter (note: this is on a manual trans car. The clutch line had to be slightly bent) Dimensions just to give a rough idea and your results may be different.

Upper line from filter to hard line (90 6an end to 6an 5/16 female quick connect). You will want to remove the intake manifold for easier access to the quick disconnect on the hard line.

Modified stock clips- I use a Dremel to modify the stock clips so the new line clips into place. The two rear clips have a larger spot that is not used so the rear two do not need to be modified.

This stock bracket needs to be bent to give a little extra clearance for the new fuel line. It can easily be bent back to stock

Rear hose/house routing. It runs pretty much in the location of the stock line and does not rub anywhere. It is a tight fit routing it up to the tank. It helps to remove the drive side tank strap bolt for more clearance. I did not measure the exact length on this hose as your results will vary depending on filter mounting.
[/CITATION]

sorry to bring up the subject, my question may be stupid
Do we drill only the entry of the rail or also the six exits towards the injectors?
Is there any point in doing it if we only modify the lpfp?
 

seb.apprenti

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Nov 28, 2018
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sorry to bring up the subject, my question may be stupid
Do we drill only the entry of the rail or also the six exits towards the injectors?
Is there any point in doing it if we only modify the lpfp?