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Here I’m going to show you how to install a Walbro 450 fuel pump with an STM bulkhead fitting.

Reason: The 450 has trouble with the feed o-ring seating when installing which causes lean condition at WOT, this eliminates that issue.

Product links:
Walbro 450:

https://www.extremepsi.com/store/product.php?productid=30208

Walbro install kit:

https://www.extremepsi.com/store/product.php?productid=27665

STM -6an bulkhead fitting:

https://stmtuned.com/products/stm-6an-black-anodized-e85-safe-fuel-bulkhead-fitting

90 degree -6an fitting (to keep from hitting pump cover):

https://www.jegs.com/i/Earls/361/921106/10002/-1
If you don’t run a line from pump to rail, just order a 90 -6an to barb fitting.

First, remove the fuel pump cover:
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Remove all hose clamps, lines, and connector (mine looks a little different because I have a -6an line from tank to rail already):
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Using a screwdriver and a hammer, unscrew the big white ring:
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Remove the white ring and set the lines to the side:
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Once it’s removed, just pull up and be careful not to damage the fuel level float which will be on the right(driver side):
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Here is my 255, removing it to install the 450:
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Walbro 255 vs Walbro 450:
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Remove the old fuel pump- screw/plug:
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Remove these 2 screws and unplug the harness and remove the float as a precaution:
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Cut off the top of the feed line as so, I used a saw:
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I used a drill press to bore out the hole to allow the fitting to sit flush:
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I then used a round file to knock off the roughness:
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Now you install the bulkhead fitting but I managed not to get a picture of it... so with permission, here’s a pic of v8s_are_slow. He also took a wire brush wheel to it whereas I did not:
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Here’s a shot from the bottom.. the lock nut will not sit flush due to the extra metal being there. You can dremel it to make it the same height although I just left it as-is. It seals from the top with the nylon washer so it doesn’t really matter as long as it’s tight (in my opinion):
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Now you’ll have to cut both barbs off the fuel pump as it’s taller than the stock/255 and will hit the bottom of the tank.
***IMPORTANT NOTE***
I highly recommend dropping the fuel pump in your tank with a line to a gas can and hooking the +/- up to help flush the plastic pieces out of the pump before actually hooking it up so you don’t clog your fuel filter.
This step can be done later after it’s fully installed by running a line from the top of the fuel pump housing and turning your pump on with ecmlink..
Whichever you think is easier:)
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I then attached the fuel pump feed to the bulkhead fitting with the supplied fuel hose and worm gear clamps:
(Don’t pay attention to how far down the pump is. This photo was taken before I realized the feed on the pump had to be cut, look at the last photo for reference where the pump should sit in the assembly)
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Here I decided to solder the fuel pump wires directly to the factory wiring. You can do this or install the connector it comes with.. Regardless, whatever you choose, be sure it has a good connection.. solder or crimp well!!!:
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Now it’s all soldered up and heat shrinked looking all pretty:
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This is up to you.. the “siphon mod”
I chose to do it to begin with.. supposed to help keep the fuel pressure down if your return isn’t big enough. I read to bore to 1/8” but no bigger so that’s what I did:
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After it’s been bored...
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Here it is all buttoned up with the sock(fuel strainer), level float, siphon, etc installed. Just reverse instructions of removal on these pieces. I happened to have a pump sock (black piece) to keep from clamping metal on metal (pump to hanger) when securing them together.
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Finally bolted up and ready for action!!!!:
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It took me 3 tries getting the right amount of pump cut off to get it to fit in the tank and I’m trying to save at least 1 other person the time I had to remove this thing after a LOT of trial and error.

If you found this install helpful and would like to donate for my time, my PayPal is [email protected]
Mods- remove this if it's not allowed.

If you have any further questions or need better pictures of instructions, feel free to message me on here or email me at [email protected]

Big thanks to Scott Laird (v8s_are_slow) for some guidance on the install.
As of now, it’s been reinstalled but hasn’t been started yet, I will update after doing so.

If you liked my thread, please find us on Facebook as we’re a shop that specializes in DSMs.
Main Street Auto & Fabrication
Located in Surgoinsville, TN

Here’s the link to my thread on how to install a fuel pressure sensor and log it with ecmlink for those interested:

https://www.dsmtuners.com/threads/h...ensor-log-with-ecmlink.519261/#post-153755086
 
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