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Walbro 450 Installation - the only fuel pump you need

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  • Walbro 450 Installation - the only fuel pump you need

    Been a while since I posted on here properly but I'm still about the the Alpinweiss is still making me giggle like a girl.

    After looking in to fitting a Bosch 044, I was pointed in the direction of the Walbro 450. This is a seriously neat little piece of kit and makes the 044 look (and sound) like something the Victorians made. Priced at £130 or so, it's good value and requires no special parts to fit, though I took things a bit further. The 450 also outperforms the 044, is silent and there are similarly sized, larger capacity Walbro pumps that people lie Audrius are using with 700bhp (with larger lines), so it's tried and tested.

    For the simple life, the 450 can just be put in place of the original S2 pump (and RS2 pump, though an S2 hose will be required). I tested the pump in the original position, with the only remotely tough thing being the swapping over the electrical plug, which took about 5 mins (I'm ashamed to say I used to the crimp connectors) and removing the top sleeve in the basket using a couple of flatblade screwdrivers (as it's too narrow)... It all works, however the perfectionist in me noticed that it wasn't quite right, so I decided to investigate.

    With the pump, the S2 hose fits straight on and I cut the plug off the OE pump and crimped it on to the supplied connector tails for the 450. When happy with it all, I'll remove and solder everything direct, so that it has only one connector. It's so simple to do that I was quite surprised.


    I decided to see how neatly I could do the job and it was easy and took about 2 hours, including learning and pondering.

    Having failed to remove the basket in the past, I tried a few methods, however a pair of mole grips on either side give me the rotation required, it was removed quickly and easily, there is a tool that does it 3037 or something.

    I had a spare basket (from an RS2, which is nearly identical), so could afford to mess it up, so decided to remove the strainer using a Stanley blade. This enabled me to see what was going on and take photos

    image_76937.jpg image_76935.jpg

    The first thing I noticed was that the top of the pump was narrower than the bottom, the second was that that the 450 was sitting a little higher than the OE pump, despite being the same length and the third was that the intake wasn't in the right place and could be obscured.

    So, to solve the size issue, well at least help with it, I purchased some fuel safe foam sleeving, which perfectly slid over the pump and gently braced it against the side of the holder. This cost less than £5.

    The height issue was due to the ridges inside the original holder, and held the intake of the 450 about 3cm higher than the OE pump. This would only be an issue with the tank being really, really empty but still, it's not quite right. Let loose with Mad Dog's favorite tool (a Dremmel), i removed these ridges, allowing the 450 to drop in nicely but still being a tight fit against the return pipe. This enabled the pump to push the pump further in but also highlighted the changes required to the holder. As I'd removed the filter to see what was going on, I decided to use new filter included in the fitting kit, which fitted perfectly and has the added bonus of preventing the pump from coming out, if it were to become a little loose.

    image_76934.jpg image_76938.jpg

    Again with the Dremmel, I enlarged the hole in the basket and chopped off the boss at the bottom and the 450 sat in place perfectly. Result

    image_76941.jpg image_76936.jpg image_76940.jpg

    With the filter fitted, I was able to install the whole thing back in the tank, taking time to adjust the hose on the pump first and then using my 2 mole method to rotate it back. Next, I used a little red rubber grease to help the tank seal slide in place perfectly, where it had caught when dry - top tip as a pinched seal can lead to leaking, fumes and other nasties.

    image_76943.jpg 20200123_105321.jpg image_76944.jpg 20200123_110836.jpg 20200123_110845.jpg

    The final thing was to install a 30A fuse in position 12, not sure if this is needed on our cars the correct thing is to fit a direct to battery harness) but it'll have to do for now and internet wisdom seemed to point to higher than normal current draw on the 450.
    Cheers'en, AndyC
    1994 ABY Coupe - Projekt Alpinweiss

  • #2
    Nice write up mate Good to see you're keeping yourself busy.
    91 Modded 3B
    14 A6 Avant Black Edition


    • #3
      Really nice write up mate...Hopefuly 7A has the same basket i want 450 or 525 pump as well . The more volts you put in pump, more power you can bring on
      Audi Coupe Quattro 2.3 20V


      • #4
        Many thanks for the very explicit documentary.
        the foam sleeve, what is the material and where did you find that?
        Last edited by ChErRyMoOn_S2; 23 January 2020, 17:05.


        • #5
          As above, nice write up.


          • #6
            I have one of these pumps waiting to go on my coupe so this is really useful.. Thank you...


            • #7
              great write up. this should be a sticky


              • #8
                Cheers all. Didn't get up to much last year due to illness and a new baby but enjoying some tinkering this year.

                Tom, 7A is likely the larger basket, I'm sure you'll be able to swap with someone fitting an 044, as the large basket, maybe even with some cash your way.

                I need to sort a relayed connection next, Error does a harness to save cutting anything.
                Cheers'en, AndyC
                1994 ABY Coupe - Projekt Alpinweiss


                • #9
                  I think this pump will deliver way more fuel than a 7a needs unless it is seriously tuned. Nothing wrong with making sure your fuel supply is up to the job though!

                  My 7a got a larger power supply wire to the pump including the wire inside the tank from white plastic cap to the pump...

                  The wire really is tiny.

                  30amp fuse in separate holder to finish off and I got 150ml more per minute just by doing that. Couldn't believe it but measured by disconnect delivery pipe at rail and pumping into jug.

                  Worth doing whatever pump you have


                  • #10
                    The factory wiring is marginal for the stock pumps when new. 25-30 years later with a high powered pump you’re asking for a fire by fitting a higher rated fuse.
                    An 044 at 6 bar draws around 13A. Way too much for a 1.5mm2 wire, even more so an old oxidised one.
                    Panthero Coupé quattro 20vt
                    Indigo ABY coupé
                    Imola B6 S4 Avant


                    • #11
                      Yeah, 30 years old tiny brittle wires are the serious problem. I want to solve this before i put an new pump in.
                      Audi Coupe Quattro 2.3 20V


                      • #12
                        useful info, thanks a lot.


                        • #13
                          Last edited by slacky; 29 January 2020, 14:45.
                          Cab 2.3E


                          • #14
                            Great post
                            Would this be same basket/design as an Urs6/4?

                            Many thanks

                            Sent from my iPhone using Tapatalk
                            Cab 2.3E


                            • #15
                              Good info !!!!