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2G Fuel system upgrade with stock fuel tank for high horsepower. Pics inside!

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v8s_are_slow

20+ Year Contributor
2,823
266
Sep 30, 2002
Panama City, Florida
So to start with, I'm putting this thread here because people are gonna be asking questions or make comments I'm sure. Just don't know if people can do that in tech articles and I wanna be as open as I can about this.

So anyway, my Walbro 450 just wasn't getting the job done for me. Sure, you can punch the relief, you can get a boost-a-pump to increase the voltage which boost the output, etc., but those are things that I just don't feel comfortable with having to do, and I'm trying to put down a good amount of power. For 1g guys, they have it easy. They have a metal tank which can be modified, and the pump is already near the rear and all. 2g guys? Well, our options are limited when it comes to "good" fuel tank and fuel supply options. Sure, you can get a Fullblown, dual pump setup that drops into the stock tank but I don't like that idea. All the fuel sloshes to the back if you're launching hard and the pumps are in the front, trying to suck it up and out of the tank. STUPID Mitsubishi engineers who thought this was a good design!!!! Frontline "was" making a fuel cell but don't think they do anymore and there's just not really anyone out there doing it and not a large market for it. You could go with a Mechanical pump and buy a surge tank. But I don't really have any room behind my front bumper to mount one, no room in my engine bay, and certainly don't want it in my car where it would be bad if I were ever to get into an accident. The stock tank really limits good fuel options for awd 2g cars. You can't weld on the tank. The saddle design means you have to get fuel out of both sides, and it was really racking my brain.

So my good buddy Mike Lester from Buschur Racing and I were talking over this issue I was having and the thoughts I had in mind when he mentioned a Beans Diesel fuel sump. I was like, "what???" If you haven't heard of it (I never had), it's something the diesel guys use (duh, right?). It instantly clicked in my head and a light bulb went off. It solved my issues that I was facing and all of the debating I was having about what system to go with. Keep in mind that I have yet to put it into use yet, but I'm doing the write-up anyway. Using this piece sent from heaven above, I was able to use the stock tank, pull fuel from the bottom, and opened a HUGE door for fueling options because now I can use any pump I want, no surge tank needed, etc. I purchased called up Beans Diesel and had a talk with them about my plans and the price concern because I would need 2 of them and that alone would've been $300. He mentioned they had a mini version for just $50 a piece and after the install, the regular size might have been too large anyway. But saved $200 right there. Cha-ching!!! The tax God blessed my bank account and parts ordering came under way. P.S. I'll try and post links at some point for every part I purchased as well. So let me stop yapping and start posting some parts porn.

New parts. Yay!!!
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This is the jewel that makes more fueling options possible.
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Installation video but keeping mind this is for the original size sump. Mine didn't come with a hole saw, but I already had the size I needed which was a 1" I believe if I remember correctly.
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I decided to scrap the metal fuel tank cover because after pulling it down some, I realized the tank wasn't completely flat on the bottom and if you drill in the wrong spot, you've just ruined a completely good fuel tank, and thus ruining your day. I also used a cordless drill for this because I had fuel still in my tank and didn't wanna chance it with electricity going through the drill and my E85 fuel. No thanks. This was a 3" hole, and was then going to drill my 1" hole for the sump, when I realized how hard it was to get the metal hole right where I needed it, not to mention I needed to avoid hitting the straps that hold the tank in there.
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Goodbye metal fuel tank cover. PLEASE be careful if you cut it out like I did. You're cutting around a fuel tank. I took proper safety precautions, that probably didn't do much for me anyway and God just spared my life for the sole purpose of this post.
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Bottom of the fuel tank. See? Not completely flat. Best spot I could find was around the middle of the tank towards the outer edge for each side. I wanted to use a spot all the way in the back but this is by far better than having a pump pulling from the top, and near the front.
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Hole drilled on one side. Tank is actually pretty thick on the bottom. I also filed the edges and got any of the crap out of the inside of the tank. I drilled VERY slowly when it felt like it was getting close to going all the way through because I didn't wanna fling plastic pieces everywhere inside the tank. This is obviously better to be done with the tank pulled out as well. Hopefully everyone is smart enough to know why.
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The piece I cut out to give you guys an idea of how thick the tank actually is.
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Sump installed on one side. Keep in mind that I didn't use the fitting that came with the sump. I purchased an AN fitting 3/8th on the sump side and -8 AN for the lines. Make sure everything is clean before you install it so the rubber o-ring doesn't start leaking. Also being careful not to bind up the o-ring and make sure it's completely flat against the tank before torquing it all down.
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Closer view.
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Here's an idea of where it sits in relation to the back tires because a lot of people on Facebook seemed to be concerned about it getting hit on something under the car being that my car is fairly low. Would be pretty difficult though because of the proximity to the tires. Not in the middle of the car where a speed bump or something would easily get it. Keep in mind that I don't drive mine much on the street though and avoid speed bumps at all cost anyway.
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Here's a look from the rear, with the -8 AN lines installed. They go up and over the rear subframe, Y together, and then to the pump. There was a hole where I could've mounted a clamp under the subframe but I didn't feel comfortable about it because it would've been under the axle and if the axle broke, I didn't want it taking out my fuel line. Pardon my not so pretty rear diff and axles. Was an awd swap with parts from a 95 that weren't the prettiest but it gets the job done.
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This is where the two fuel lines Y in together after coming up and over the subframe. I drilled holes and mounted the clamps on the driver's side of the spare tire wheel well.
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And another view. The swaybar looked like it was meant to be bent in that area. The fuel line tucked nicely under it. I drilled a hole and clamped the fuel line to the bottom of the rear subframe because I wasn't exactly sure how much the swaybar would move and I didn't want it rubbing against the line over time. From there it goes to the first fuel filter which I mounted to the front of the spare tire wheel well.
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New fuel pump compared to my Walbro 450 pump. This is a Magnafuel 4303, external pump. I believe the largest external pump that you can buy without a controller. Or so I've read anyway.
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Pump mounted on the passenger side of the spare tire wheel well. Then from there it goes to the after filter, which then goes back up and over the rear subframe, around the side of the fuel tank, and up to the front of the car. Prefilter to the bottom left of the picture. Had to cut all the lines and install the fittings to get them routed to where I needed them. Tried getting a few different angles for you guys.
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Good view of the pump and where I drilled for grommets and ran the wiring through to the inside of the car.
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Ran the 10 gauge power wire up along side the wires for my battery relocation wiring, and up to the relay for the fuel pump rewire. If you look closely, you can see where the ground wire comes in and goes to the negative terminal of the battery through the battery box.
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Annnd to the front. I have it coming into the rail, from there I have an AN fitting to allow me to screw in my fuel pressure sending unit so I can log fuel pressure, and then u-turn and back to the regulator. Now I've heard that my placement for my regulator might not pass tech at the track. They're not strict about it around here and honestly, all I do is test and tune anyway. I HATE bracket racing. Just enjoy going fast and doing heads up racing. Y'all do what y'all want. But also too, the intake manifold being as large as it is makes it hard to mount closer.
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And the regulator. I upgraded the regulator after talking it over with Kevin Jewer who said the return orifice in my Fuel Lab regulator might be too small and keep the fuel pressure high. Sooooo, I didn't wanna screw around. I purchased this regulator from Magnafuel as well. Figure if they make the pumps, then surely the regulators would get the job done.
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The biggest pain of this job was fitting -8 AN lines between the body and subframe for the supply and return, but I managed. This piece of crap here had to come out to make room for the -8 lines, along with removing the stock metal lines. And I kid you not, it was a PAIN!!!!
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This is the bracket that holds the plastic piece above. Again, Mitsubishi engineers are DUMB about where they placed this. I put a magnet on the bolt to keep from dropping it when I finally managed to get the bolt out.
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Now for the final piece to finish up. The stock fuel hanger and the return line. I had to cut pieces off to get this to work. I had originally used a -6 AN line with my Walbro 450, with a -6 bulkhead fitting. I didn't wanna mess with it so I capped it off and drilled 2 other holes for a vent/rollover valve, and a -8 AN bulkhead fitting for the return line to dump the fuel back into.
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To be clear on what's what.
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This 90 degree bend was too tall and stuck out through the top so had to order a shorter piece.
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After installing the shorter piece, everything fit in there nice and snug.
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After all said and done, this was all the fuel line I had left. Shew! I cut it close. Anyway, I'll post up more later. It's late. Links to parts and such. Y'all have a good one.
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Here's a video if y'all prefer. Most of the fuel stuff is filmed towards the end of the video. I'll get more pictures of it when it's up and running. Had to send my injectors off to be cleaned thanks to the E85. Still have links for the parts I need to post up as well. I'll get to it eventually.
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This solved... sloshing to the back of the tank, is that right? The placement doesn't look towards the back so I'm a bit puzzled. For fueling... you say there are no good options but are you familiar with a lift pump to a main pump setup? Also in regards to sloshing what about turns or braking?

I mean this looks interesting but I don't see... why any of this is a good idea. A lift pump to a surge tank with a pump solves your issues plus pretty much all others and actually seems like less work than this.
 
This solved... sloshing to the back of the tank, is that right? The placement doesn't look towards the back so I'm a bit puzzled. For fueling... you say there are no good options but are you familiar with a lift pump to a main pump setup? Also in regards to sloshing what about turns or braking?

I mean this looks interesting but I don't see... why any of this is a good idea. A lift pump to a surge tank with a pump solves your issues plus pretty much all others and actually seems like less work than this.

I'm not sure if you read much of my post but you probably missed this part here.

"You could go with a Mechanical pump and buy a surge tank. But I don't really have any room behind my front bumper to mount one, no room in my engine bay, and certainly don't want it in my car where it would be bad if I were ever to get into an accident."

And again, here, "Best spot I could find was around the middle of the tank towards the outer edge for each side. I wanted to use a spot all the way in the back but this is by far better than having a pump pulling from the top, and near the front."
 
Install is clean I only see one problem. Your use of 2 sumps and a Y fitting to bring the two sumps together. The reason is that now if either of the sumps go dry you are going to lose prime on the pump even if the other side still has plenty of fuel. This could happen in a hard turn or under launch with low fuel.

That's why the stock system only draws from one side and uses the return to transfer fuel from the drivers side to the passenger side of the saddle. You could have stuck with that type of a transfer system and only used one of your sumps. Or else you would need 2 pumps one for each side to solve this problem which isn't really cost effective.

I do like that bolt on sump piece for plastic tanks though. Haven't seen that before and it is a really cool solution for applications where you can't weld on a sump as you said in your post.
 
I'm not sure if you read much of my post but you probably missed this part here.

"You could go with a Mechanical pump and buy a surge tank. But I don't really have any room behind my front bumper to mount one, no room in my engine bay, and certainly don't want it in my car where it would be bad if I were ever to get into an accident."

And again, here, "Best spot I could find was around the middle of the tank towards the outer edge for each side. I wanted to use a spot all the way in the back but this is by far better than having a pump pulling from the top, and near the front."

A mechanical pump isn't required for a surge tank; they're completely unrelated. You also should have room up front as you've shown us your huge ass battery is in the trunk. Up front, where the battery usually is placed, is where my surge tank is with an internal electric fuel pump is currently. It's even better to put everything there for you considering this is a drag car

As for the placement comments, I did read why you compromised but who cares why, it's still a compromise of the overall solution to fuel slosh. You have to agree this is not ideal with the sumps still being a good distance from the back, and still leaves all the other issues cited which again are solved by a simple surge tank. So that raises doubt in the real efficacy. So with this theoretical improvement to the sloshing problem how much of an improvement is it really? How low of a tank can you now have and have no stuttering on launch and throughout a 1/4 mile pull? I'm asking that knowing you haven't tested it, and that's my point. It's a compromised theoretical solution vs a known full solution at a similar price.

I do think you did a clean installation job here but I just don't think the cost/benefit analysis makes sense.
 
I know everyone has an opinion, and that's great and all, but I feel the results need to be there before we make any claims on how this will be a problem, or that be a problem. It's not running yet so even my opinion may not matter because I may feel like it'll work, only to fall on my face. Others may feel it won't work and I may not have any issues at all.

But my "thinking" is this. You have two people drinking through a different straw that's in the same cup. One person stops drinking while the other continues. Does the person drinking suddenly suck up air? No.

I don't have anywhere for a surge tank because I have a side exit exhaust on one side behind my bumper and my fuse box on the other side which was relocated. The battery might be relocated but I have things in place of it as well.

Let's see how well it works, then let the opinions fly. If it doesn't work as I anticipate, I'll revamp and improve on it. But can't really know without trying, and I'm sure I'm the first to attempt this type of setup. We'll see.
 
You eliminated the stock return/Syphon. How are you going to have equal fuel in both sides of saddles?

Your thinking about it all wrong. It's one person(pump) with two straws(each saddle) in his mouth and two different cups. You're going to suck in air when you finish the one cup . It's a given. There's no maybe.
 
[QUOTE="v8s_are_slow, post: 153681853, member: 4883"But my "thinking" is this. You have two people drinking through a different straw that's in the same cup. One person stops drinking while the other continues. Does the person drinking suddenly suck up air? No.[/QUOTE]

I am curious to see how well it works for you it may be a non issue. But as far as the two sumps are concerned it is simple hydraulics and your analogy is completely wrong. The fuel pump is your "person" so you only have one of those not two. And as the post above states one person with two straws in their mouth with one inside the liquid and the other outside the liquid will not be able to draw any liquid into their mouth.

Its as I said in my previous post, with two fuel pumps, one on each sump then your system would work as you are thinking and when one runs dry you would still have fuel pressure. But as it sits right now if one sump runs dry you are going to lose prime on your fuel pump and lose fuel pressure as a result.

This is FACT now you are correct though that this has not been tested. So this problem may be big or small depending on the situation and how you drive. You may not notice it except in extreme cases. But make no mistake it WILL happen.

The reason I say that is that the factory fuel pump has a bowl to hold fuel in a slosh situation. You have eliminated that feature in your system so slosh is inevitable in low fuel situations.
 
Just because one side runs dry, does this mean the other side that has fuel in it will no longer go to the pump??? It's just going to suck in air at this point? I totally don't understand how y'all are coming to this conclusion when fuel will still be Coming from the other side.
 
I dont get why dont you understand its going to suck both air and fuel. Any kind of air in the fuel system is bad. Momentary lost of fuel on a cylinder due to an air pocket at high load, bye bye engine. There's a reason vapor lock is bad. Introducing air has a similar effect.

It's easier to pump/pull from a lower restriction hose, and that's the side that's empty. Try the two straws(one in cup,one outside) thing yourself and you'll figure it out.
 
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Just because one side runs dry, does this mean the other side that has fuel in it will no longer go to the pump??? It's just going to suck in air at this point? I totally don't understand how y'all are coming to this conclusion when fuel will still be Coming from the other side.

We can't help you if you don't understand the basics. Seriously try sucking up water through two straws at the same time one in the cup of water and the other out in open air. Your not going to get any water in your mouth. Its basic principles of Vacuum.

You don't suck it up, the atmospheric pressure around you pushes it up the straw when you create an area of lower pressure inside the tube. There has to be a differential pressure for this to happen.

So if one of your sumps goes dry that means the pump can no longer keep making this differential pressure. The atmosphere and the pump suction are at the same pressure and no matter how much liquid is in the second sump no fluid is going to be pushed up to the pump suction.

You are thinking of your system like a gravity feed. If the pump was mounted BELOW both of the sumps of the tank then no vacuum would need to be created and the one sump could run dry and the other would still DRAIN down to the pump.

Where your pump is mounted and with the Y fitting between the two sumps if one of them is sucking air then you are not going to get any fuel pressure. Plain and simple. The more likely scenario is what lasthope is talking about where you end up with air pockets in your fuel line where the sump goes dry for only a fraction of a second and gets recovered. Very common with slosh.
 
Okay, so let's say this would really be an issue. If that's the case then I need to find a solution. Only thing I can think of is something like a flapper valve in a toilet where if the fluid level gets low on the drivers side, a valve would close and shut off to prevent any air from being sucked in.

An inline check valve would be great, except that I don't think it would shut off when that side of the tank goes empty. So I'm busy thinking of a solution so I don't have to even worry about it to begin with.
 
Its all installed now so you should drive it and see how much of a problem this becomes. With more than 1/2 a tank of gas I be you never notice any problems. And below that it will probably only happen in hard cornering or launching the car. Problem is that you can start running lean on one cylinder with air pockets in the line before you really start to feel the car being upset.

Your right a check valve isn't going to help you because you always need flow in the same direction just not when the sump is dry. A flapper like you are describing might do it but will be hard to implement correctly.

This problem of not wanting to draw air when fuel sloshes is not new. People have been trying different baffles in tanks for years. Look at the Holley Hydramat. It claims to be able to draw fuel even when it is not entirely submerged in it. Similar to what your system needs. It works with a special porous material that expands and seals up without the presence of fuel to maintain vacuum. Total gimmick. I know from personal experience that the material gets degraded after a while and you start sucking air.

The easiest solution to the problem with the way your system is set up now is to add a second pump. Thats if you don't want to dick around with baffles and flappers and what not. Go down to the auto parts store and buy the cheap inline fuel pump for carbureted cars. It's like $20 because it's not meant to provide any pressure. Remove your Y fitting and plumb your passenger sump directly to your Magnafuel. Then put the cheap inline pump on the drivers side sump and run a line to that 3rd port you plugged on your original fuel pump hanger. Wire up the second pump so it runs whenever the main pump is on. Now you will always be transferring all your fuel to the passenger side of the saddle. If the drivers side runs dry and that pump sucks air its no problem because its just a transfer pump. This will always keep the magnafuel pump in fuel. This basically emulates the way the original system is set up in a much more complicated way.
 
Also, I don't know if you read the literature on that pump or not but they want a -10/-12 hose on the feed side, not the -8 you're currently running.

Lots of research you skipped over.
 
Also, I don't know if you read the literature on that pump or not but they want a -10/-12 hose on the feed side, not the -8 you're currently running.

Lots of research you skipped over.

10an in/ 8an out is what magnafuel recommends on this pump unless youre making over 1000hp then you go to 12an if iremember right from talking with them.
 
I'll respond more when I have more time but this pump has -8 AN inlets and outlets. My fuel filter has -8 AN openings. All ports on my "Magnafuel" regulator has -8 openings. I see nooooo reason to put in bigger lines than that. Not sure what research I "skipped over". Smh...

P.S. I also called them and went into detail about what my plans were with this fuel setup and the sizes lines I planned on using. Never once did they try to tell me to use something different.
 
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mag
I'll respond more when I have more time but this pump has -8 AN inlets and outlets. I see nooooo reason to put in bigger lines than that. Not sure what research I "skipped over". Smh...
magnafuel still recommends running a 10an feed from the tank to pump so theres plenty of volume going in. it does state that in the paper work that's sent with the pump.
 
They want either a -10 or -12 on the inlet side. Just have a look on there site where they provide fittings for the particular pump. Also their fittings have larger orfices than the rated size compared to others so it's best to use theirs or drill out competitors fittings. It has to do with being able to feed the pump enough to prevent cavitation.

Do you seriously think we are making this up or something? You should give them a call and talk to them if you don't believe us....

http://www.magnafuel.com/fittingkits.html
 
I did call and talk to them. Last write-up I think I'm gonna do.
 
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