LS engine fuel supply


Well-Known Member
Nov 16, 2019
I wrote that little piece for another forum member, but I figured that may be useful for others so I'm sharing.
This is super basic info, so if you already know about it, that's cool, I'm just trying to help who doesn't know.

Soooo, you want an external pump system for your stock-ish LS engine, or any dead head rail TBI engine ?


(1) Walbro 255 fuel pump

(1) Wix 33737 fuel filter regulator

If you want to plumb everything with fuel injection rated hose, these 2 parts are enough. Get some hose clamps, hose and go to town.
If you want to convert everything to AN fittings/hoses, AN6 for everything will be more than enough. For this you will need :

(2) Russel 670470 fittings to convert the fuel pump metric threads to AN6

(1) Russel 640940 fitting to convert the female 3/8 regulator outlet to AN6

(1) Russel 644123 fitting to convert the male 3/8 regulator inlet to AN6

(1) Russel 644113 fitting to convert the male 5/16 regulator outlet to AN6

Then you will need the corresponding AN6 hoses and hose ends but that's dependent on your vehicle.

This is how you plumb the regulator:

Make sure to wire your fuel pump with some 12ga wires and a nice clean system (good grounds, good relay, good crimps, etc). A 20amp fuse is good for this pump.

You can install the regulator as close or as far from the fuel pump as you want.

There are many other ways to get the job done. This isn't even what's in my buggy. But this is the simplest, cheapest, easiest way to get the job done while staying safe.

Do not buy the chinese copies of these parts, you'll save $80 but will have problems down the road, I can guarantee it.

If you have a fuel rail that has an integrated regulator (like the early vortec engines), you don't need anything that's related to the regulator. Just a fuel pump and that's it.

And you're good to go.

Now if you want to add a hydramat (really pick up the last drops of fuel, highly recommend), here is what to get, FOR THE INSIDE OF THE TANK.

(1) Hydramat that fits in your tank. The different options are here:

Then you need a way to connect the hydramat from the inside of the tank to the bulkhead fitting that's on the outside of the tank and a solution to keep the hydramat from moving around in the tank.

For this I highly encourage you to use hard line plumbing because it will do both jobs at once. Move the fuel between the mat and the fitting and keep the mat in place.

Some people use submersible hose, but it'll leave the mat floating around inside and that's no good.

I buy all my hard line shit for the hydramats at my local Ace Hardware and it's super cheap too.

You'll need :

(1) 3/8 MIP to 3/8 compression fitting
(1) 3/8 compression to 1/2 FIP fitting
(1) 3/8 aluminum hardline (sold in like 4ft lengths)

The second fitting is 1/2 FIP on one end since this is the most common bulkhead fitting that's used in a fuel tank (AN8). If you have a AN6 you should use a 3/8 FIP. If you have a AN10 you're fucked and need a reducer since 3/8 compression to 5/8 FIP isn't available. But I highly doubt it.

If you're doing it right, it should look like this when you're done.




Any questions, just ask.

Also, I used a 90 degree 3/8 MIP to 3/8 compression fitting in my example because it packages better, but it's up to you to use whatever works. Use common sense.


Recovering Project Junkie
Nov 5, 2005
Newton, NC
Awesome, thanks for posting the info. Any suggestions for putting the pump inside the tank?

Also, I assume that you would need a different regulator, if you are running return style fuel rails? or just block off the return?


Well-Known Member
Nov 16, 2019
If you want an intank pump I'd suggest a 2002 Silverado pump module. Very easy to install.
Holley or Aeromotive makes some drop in pump modules that are more universal, but more $$$.

If you have a return style engine, you do not need any regulator. It is integrated in the rails. You'd need a 10 micron filter before the engine though.


Wizard of the woodsman's colony
Aug 15, 2009
Here's what I run for in-tank. Return style rail, factory FPR. I plumbed it inline with a stock gutted TJ pump assembly.