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Fuel Sump Install, pictures, tips and tricks!

70K views 33 replies 22 participants last post by  Wrecker426 
#1 ·
So I'm taking the time to share my experience with you guys about my sump install and some things to keep in mind when doing yours.

A little background, a fuel sump is a very simple apparatus that bolts to the bottom of the fuel tank to allow fuel to constantly go into as its the lowest portion of the tank. The two most common advantages to this are,

No 1/4 tank or less starvation.

More fuel flow for higher horsepower applications.

It has been discovered by a few that the factory draw straw in the fuel tank becomes restrictive somewhere above 600hp. The fuel from factory gets sucked up like a straw in a cup. It pulls from the bottom, but has to go upwards before traveling out and away from the tank.

The nice thing about a sump is, gravity is constantly pulling fuel down so its never left empty or dry unless there's no more fuel in the tank!

Something to keep in mind when purchasing a sump, get one that seals with O-rings! Most do, but there are some that come with a paper style gasket. Ive installed both types before and the paper gaskets are much more prone to leaking!!!! The o-ring's seal much better and even if the surface isn't 100% flat, it'll still seal. I have a DRP unit, but other popular choices are Beans, Diesel RX, XDP, etc.

Some tools and things you'll need is,
3" whole saw with centering bit.
Basic hand tools, 8, 13, 15mm socket
Allen keys.
If gutting the sending unit basket like I did, a air sawzall and die grinder.
Clear Silicone
Drill, Assorted Drill bit set
1/2 quick disconnect fuel clip tool.
5 gallon bucket
Small pry bar and hammer

BEFORE INSTALLATION HAVE AS LITTLE FUEL AS POSSIBLE IN THE FUEL TANK!!! It will make life a lot easier!

First thing you want to do is remove the protective fuel tank cover with two 13mm bolts and pull over the tabs on the right side of the tank by swinging it down.

Now you'll be looking at the very bottom of the fuel tank. You'll see indents towards the rear of the tank. Directly in the middle of those are the fuel sending unit. That's where Ive seen most other people and I put the sump. Putting the sump here will help with receiving fuel under acceleration and the factory fuel return line is releasing the extra fuel here.


Next you'll measure out the 100% center point of that circle that bulges out. Its perfect size for a sump. I used dial calipers for this but I'm sure a tape measure will work too. Once you're sure you have the center point, mark it, and then the fun begins. Put the 3" whole saw WITH centering bit in your drill. Grab your clean 5 gallon bucket too.


Drill with the center bit until you get through the tank and fuel will start to drip out. Remove drill, use bucket to catch the remaining bit of fuel that you had left in the tank. This is where the least amount of fuel in the tank, THE BETTER!!!!!

Once the fuel is completely out of the tank, you can stick the drill back in there. You'll now proceed, and drill until the 3" bit makes it all the way through. This is what you'll see.


That tan housing you see is the sending unit basket. Here is where you either install your sump by pushing the basket up, or you drop the tank and do things a little more thorough. The advantages of doing this is, The fuel level sensor clips into the basket. If you push the basket up, you're moving the level sensor up as well so fuel readings from your cluster wont be 100% accurate. Another reason is, with the sump sitting directly under this, you aren't really allowing enough space for fuel to flow down into the sump. It definitely wont starve it, but opening up the basket will be more of a piece of mind in my eyes. Also you'll get to clean the tank of all plastic shavings and debris from drilling!!!

Here I chose to pull the tank once I got to this point. Pulling the tank is fairly simple. Holding the tank in, you have two straps. A 15mm bolt holds up each strap. You also have the filler neck (8mm hose clamp), one electrical plug on top of the sending unit, a over flow hose at the sending unit (8mm hose clamp), and a return line quick release and the feed line which most likely goes to a lift pump if you already have one. I dropped my tank on my garage floor all by myself with the help of a floor jack, its not very heavy.


Now that you have the tank out, you can remove the sending unit.


To remove, there's a big black metal ring holding it in. Take a small pry bar and a hammer and tap it counter clockwise until its free. Now you can remove the unit from the tank. BE CAREFUL AS YOU HAVE TO MANEUVER IT A LITTLE ONCE YOU GET TO WHERE THE LEVEL SENSOR IS.


With the sending unit out, you have now see how everything works. The level sensor can be unclipped and set off to the side and the basket unclipped from the very bottom. Here is what it looks like but at this point I started to hallow the bottom out already.


What I realized next was, to accurately get a correct fuel reading, I measured the height of the sump clamps that would be pushing the basket up. I added another 1/2" to accommodate the bolts that come through them clamps. Some of you may not need to do this because the newer sumps only have one or two bolts in the middle to fasten them. My sump uses 10 bolts that take up the whole size of the outter basket.



Once you have that measured, you can use a air sawzall to cut the bottom of the basket off and shorten it. It will then look like this.



I then took a die grinder and made four big passages on the very bottom. This is very critical in a way. If you run your tank rather low on fuel, this will allow fuel to flow down to the sump WITH EASE. Keep in mind this basket sit directly on top of your sump clamps. This is how it looks.


Next I went ahead and chopped the little nub off the bottom of the factory fuel pick up. This will allow more room between the sump and this part.


Now you can put the sending unit back together by clipping the bottom back on, then clipping the level sensor back on. Obviously make sure everything is clean, clean, clean!!!


Next BEFORE putting the sending unit back in, I cleaned the tank free of any shavings or debris. Then I installed the sump with the tank out of the truck and sending unit removed. Makes life much more simple. Note: When Installing the sump, be sure to use the silicone around the o rings and mountings bolts if yours uses the 10 bolts like mine. If yours has one or two center bolts, no need to worry about them.


With the sump completely installed, now you can install the sending unit. Same way as it came out, maneuver the level sensor in first, then slowly drop down. Install the black ring over the sending unit and turn clockwise with the same pry bar and hammer. Here I removed the big black plastic fuel line that was used as the feed before. That will no longer be needed!!!! I took a rubber cap and put it over the opening on the fuel tank lid where that line use to go. This will keep all dirt and crud from getting into your fuel tank. The tank is now ready to go back in the truck. Using a floor jack, lift it up enough where you can get one strap on then proceed to the other. A BUDDY WOULD ALSO COME IN HANDY TOO. Once back in, hook up the following lines you originally disconnected, Fill neck, electrical connector, overflow line, and just the smaller return line. The feed line will now come from the SUMP!!!

When installing the 1/2" hose barb on the bottom of the sump be sure to use pipedope or teflon tape used for gas or liquids. You can now run a 1/2" fuel line from the sump to the lift pump. HERE I USED A BALL VALVE THAT I ADDED IN FOR THE CONVENIENCE OF CHANGING FUEL FILTERS AND WHAT NOT TO SHUT THE FUEL SUPPLY OFF.

Next you can trace out a 4" circle in the fuel tank protector and cut it out with a air sawzall. I ran my feed line between the tank and tank protector to try and keep it as safe and out of harm as possible.


This might be a little overkill for some, but I'm very thorough with the things I do to my truck. I now have a clear path to the fuel sump inside the tank, a proper fuel level reading, and a nice clean setup! I was able to make over 800HP with this setup so I can definitely say it works like a charm! I hope you guys learned something or at least have something to view when you install yours!
 
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#3 ·
Nice! This is definitely something I am going to do sometime this spring, I plan on going with the G&R sump because of the 1 bolt design and the return is built right in as well
 
#6 ·
Sub'd
 
#7 ·
Great write up for sure! I plan on doing this really soon and this will come in handy!
 
#8 ·
Great writeup!
 
#9 ·
what kind of cap did you put on the stock supply hose spot and what did you do with stock fuel line. I need to install my sump and lift pump soon.
 
#12 ·
I used a rubber vacuum cap to cover the port where the old fuel line use to go on the fuel sending unit lid. Look at the fifth picture down, you see there's a black fuel line to the left of the tank? That's the original feed line that the draw straw uses. With a sump you no longer need it so I simply removed it off the tank and now sitting on my shelf.
 
#10 ·
Killer tech thread b5!!! Thank you for this ! Liked, sub'd, & saved !!!
 
#11 · (Edited)
Thanks everyone! I'm thinking we should sticky this just so it doesn't get buried and no one can find it. I really do think it's helpful for those that will be doing their sump and also the people that demand more fuel like me have an idea how to open up the basket to get a nice free flowing path to the sump! Also while keeping an accurate fuel reading at the same time. It's a win win overall.
 
#13 ·
Has anyone tried or is there a way to use the old pickup as a return for the lift pump rather than install in the fill tube? Just thinking this would be a clean way to do a return since its already there.
 
#14 ·
I have heard of people trying that, but for some reason it doesn't work very well. I can't remember why tho...
 
#15 ·
Great writeup. But after watching videos of like the bean install why not just install it on another flat spot of the tank. Wouldn't that be a lot less work then messing with the sending unit?
 
#17 ·
You ask a good question because I always wondered this as well. Why under the sending unit???? From everything Ive gathered so far, there are two benefits to this. The first one being the return line from the engine goes to the sending unit so theoretically that will always be supplying the sump with fuel (even though the sump will always have fuel anyways because its the lowest spot). The other is because the sending unit is towards the back of the tank. These two main reasons are beneficial to drag racing. The point is to have as little fuel in the tank as possible. The less the fuel, less weight. When you pull a 1.8, 1.7 or 1.6 60' at the strip, the fuel is immediately be thrown towards the back of the tank. With the sump being in the back, it will always have fuel even with as little fuel in the tank as possible. Everything is in theory, but it is what it is. Some don't care, most don't race their trucks so not many go to this extent.

If you put your sump towards the front of the tank (theres not enough room on the back portion of the tank unless under the sending unit) than I'm sure you'll be fine. It really isn't gonna matter in most situations.
 
#18 ·
Ah that's makes a lot of sense now. I never thought about drag racing and keeping low amounts of fuel. I just use my truck for hauling the trailer so I might skip the work of going under the sending unit. I never let my truxk get under 1/4 tan anyhow.
Your writeup is awesome and helpful. Thanks for the discussion.
 
#23 ·
I did not.

I only needed to dispose of a gallon or two, and the bucket I used to drain the fuel into was not clean.

I put about 2-3 gallons of fresh fuel in after the install then drove to the pump to fill up.
 
#24 ·
Any chance anyone knows what this part does and if its needed, with a sump install??
I was pushing up on the basket with a screwdriver to get my sump piece in through the hole and this popped loose and fell out. Really hoping I don't have to drop the tank again.
 

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#26 ·
I'm stumped. Are the two ends hose barbs or mounts?
 
#27 ·
It is in the OPs picture of cutting off the fuel pickup, on the left side standing vertical. You can see the end of it at the left side of photo.
 
#31 ·
Dang man! Nice work. Sick thread. This will help a ton of guys out.

I just purchased a 2-screw RPM sump off eBay. I'll definitely be pulling the sending unit and making the same basket mods. If you're plumbing the lift pump to the sump this seems to be the most logical solution. Plus I'm also curious to see what kind of crap my tank has collected over the years.
 
#33 ·
Just a follow up since I've done a whole bunch of sumps, I'd go in the rear of the tank, that way you don't have to do this. The rear of the tank is the most flat and will give you the best seal. I've about ran my truck out of fuel and never an issue. If you already have the sump under the basket, than you can refer to this mod. This is my second account since my password was lost for the first one.
 
#34 ·
Just bought an duramax again been out of the loop for 6 years now, confused as to why a FASS 165 could draw from the suction side but it would t be good enough as a return even if it was trimmed as you said, the return should be less then supply, maybe in bigger HP applications and a dual low side pump it would need to be opened up, that being said then why not put a bulkhead AN fitting on it for appropriate flow, that way your not cutting the full neck 🤷🏼‍♂️, it would just return both lift pump and CP4(3 if your fortunate) in the same place we’re it needs to be drawn from?
 
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