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Thread: DIY: Upgrading Fuel Pump Assembly

  1. #1
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    DIY: Upgrading Fuel Pump Assembly

    Measured the fuel pump pressure, one side was hitting 70psi and keeping the pressure, the other hitting 60 and bleeding off to 0 within minutes.
    While running at idle in line pressure gauge was showing 40psi on one side and the other 36psi.
    We took the pump assembly out and changed out two hoses, it helped a bit but the problem was still there.
    Decided to upgrade both pumps with 255LPH pumps. At the same time got rid of those twisty hard lines that I was pretty sure were leaking at the connectors and installed submersible fuel lines directly connected from the pumps to the assembly.
    Replaced all the cracked wiring.
    The pump holder needs to be modified at the bottom so the new pumps would fit. Basically an existing hole enlarged out to fit new inlet. Very easy! The aftermarket pumps come with a jacket that makes them a perfect snug fit inside the holder. The hardest part was fitting the hoses, use heat and lube


    Sent from my SM-G925T using Tapatalk
    Last edited by dragon850; 09-14-2017 at 11:30 PM.

  2. #2
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    Great info!
    Is It holding a balanced pressure now and not overwhelming the regulators? Be nice to get a crack proof fuel carrier.

  3. #3
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    Quote Originally Posted by 8eights View Post
    Great info!
    Is It holding a balanced pressure now and not overwhelming the regulators? Be nice to get a crack proof fuel carrier.
    The fuel pump assembly is re installed on the car. Have not run the pumps yet because I am changing the fuel filters and the molded lines, I will post another thread tomorrow on that procedure with some cost saving tips! I am very confident in this set up, 220psi line directly to the carrier nozzle. Unlike the OEM pumps, these can rotate inside the holder allowing for straight shot and eliminating stupid plastic twisted hard lines!
    Yeah cracks in the carrier itself is a deal barker, thankfully my car only has 48k miles on it so plastics are not terribly degraded. However fursideup had some success re sealing the carrier with a special Loctite epoxy!

  4. #4
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  5. #5
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    Started the car today, seemed to run really well. Pumps are strong, filled up empty fuel filters and rails in seconds.
    I recommend using FI ABA clamps only.

    UPDATE: I highly suggest using Walbro GSS340 pumps instead of the above pictured CNT racing pumps due to quality (fitment will be identical). Here is the link to Walbro Pump: http://www.ebay.com/itm/Walbro-GSS34...53.m1438.l2649
    You will need to buy 2 kits to install Walbro pumps, you will use submersible line, pump sleeve, filter sock and electrical connector, toss the Chinese pump that comes with a kit in a garbage or use it for emergency spare:
    http://www.ebay.com/itm/High-Perform...FZEsOF&vxp=mtr

    UPDATE 9/10/17: A second set of warranty CNT racing pumps is starting to fail, started the car in the AM and it ran on 6, there is power to both pumps but no fuel from 1. Restarted the car and it fired on 12, so one pump is becoming intermittent. Just ordered a set of Walbro GSS340 pumps from above mentioned Ebay link. However as I educate myself further on fuel pumps it seems that many Walbro pumps sod out there are Chinese replicas that look 99% identical to the real thing so when I receive my Walbros I will do my best to identify them as genuine or fake and post and update here.

    Update 9/13/17
    Received the Walbro pumps from the ebay seller in the link mentioned above, it was a great price so sounded a bit too good to be true but I personally verified that indeed these are genuine Walbro and not fake knock offs.
    I removed the link to the CNT racing pumps as I was very disappointed in the quality, they just did not last...



    Update 9/21/2017: Installed Walbro pumps, car started right up. Pumps operate in silence, I could hear just a very slight whine if I put my ear to the pump cover.
    One thing that is absolutely essential is to order 4 pump isolators, the old ones are actually disintegrating and contaminating your tank! Here is the link: https://www.fcpeuro.com/products/bmw...nt-16141180474

    UPDATE 10/4/2017 : After Walbro install realized my fuel rail pressure was 75psi lol, after much discussion with cartoonz and testing we determined it was not the FPRs that were being overwhelmed, it was sending units fuel return part. At idle it could not flow the volume of fuel being returned to the tank. Solution is simple, drill small hole (smallest drill bit) in the U section of this part. All is good now. Walbro gss 340 is a beast!
    Hook up a fuel guage and test your pressure before doing this, to see if your pressure is also high.

    Last edited by dragon850; 10-05-2017 at 12:23 AM.

  6. #6
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    Quote Originally Posted by dragon850 View Post
    ...Also don't recommend soldering the new wires in, just extra unnecessary work..use crimping tool and connectors to seal wires together.
    ...and you were doing so well demonstrating best practices before that... lol Hey, are these "coated" too?
    solder & heat shrink is far superior to a crimp connector, just saying...

  7. #7
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    Remember once I get 5k boosted miles you gonna have to admit the coating works right here on the forum I believe that was the deal lol


    Additional important info by dragon850:
    Fuel Pump upgrade sticky UPDATE
    Want to make everyone aware of the changes I made to fuel pump upgrade thread sticky, the CNT pumps I have used turned out to be pretty poor quality. Since the original post I have done a ton more research into fuel pump technology, Walbro utilizes gerotor design vs practically all Chinese pumps use vane design that creates higher internal friction and because they usually utilize sub par quality materials vane pumps fail fairly soon.
    I apologize to anyone that followed my lead and purchased originally recommend CNT racing pumps , if you did, use them till they are dead then go with Walbro GSS340.
    https://www.bimmerforums.com/forum/s...-sticky-UPDATE
    Last edited by shogun; 09-16-2017 at 01:44 AM. Reason: added update

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