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    Fuel System Build

    Ok, this might be a long post...

    After much headscratching, I've come to the conclusion that the gas tank in my '84 Eta is full of rust (and god knows what else). This has destroyed both of my fuel pumps and likely blocked much of the hard fuel line under the car. I have a new set of injectors and a known good regulator, and an inline gauge tells me that I am not making enough fuel pressure. Relative to manifold pressure, I'm only getting about 2 bars with a 3 bar regulator. This is bad. If I try to autotune on my MS3, it wants to run a VE of 65 at idle to try to compensate for the lack of fuel feed.

    So, I want to install a fuel cell, an inline pump and mesh filter, and a new regulator. I'm planning on buying everything from Summit because their main location is very near where I live. This car, for now, is strictly a street car with a stock engine and stock suspension. Here's my plan:
    • A 12 gallon Jaz fuel cell with 70-10 sending unit (fits in spare tire well)
    • Pre- and post-pump fuel filters
    • 35-70psi adjustable pressure regulator
    • AEM 385 Lph inline fuel filter
    • Appropriate vent fittings and check valves


    I plan on cutting out the spare tire spindle mount and setting the cell in the spare tire well padded with some dense foam, and strapping it down with some steel bands. Before I spend a whole bunch of money on parts, lines, and fittings, I have a few questions for this fine community. I appreciate any pointers you can give me. I've done some research, but ultimately I've never done this before.
    • I've read in multiple places that "fuel pumps are meant to push, not pull," and that you should ideally mount the fuel pump below the bottom of the cell's sump. I've read elsewhere that you can mount the pump up to 18" above the sump with no bad effect. I'm more comfortable with this arrangement because should a line break or a fitting leak, it won't just piss all the fuel out. What is best practice here?
    • The outlet of the fuel pump and the inlet of the regulator that I've selected fits -6 AN lines. The factory fuel rail has an integrated regulator and a barb fitting for our familiar 8x13mm fuel line. What is an effective way to attach these -6 AN lines to the inlet and outlet of the fuel rail? If my math is correct, the ID of a -6 AN line should be right around 8mm, give or take 10 thou or so. Is it acceptable to just hose clamp the feed line onto the barb fitting on the fuel rail? As for the return line, can I just run it through a factory regulator with the pressure reference line disconnected? I see that Nuke Performance makes fuel rails for the M20 that feature proper -6 AN fittings (and are quite pretty), but I am unclear on how these are intended to be mounted. Has anyone installed one of these before?
    • Is it foolish to route the feed and return lines through the driver's compartment of the car? I've seen mixed opinions on this. For that matter, is the spare tire well a safe location for a fuel cell? I'm not terribly concerned with the shifted center of mass for now. I'm fully expecting to give up trunk space, and I'm fine with this.
    • Tank foam or no tank foam? PVC wiffle balls? This is only a street car for now.


    You might ask why I don't just get a new OEM tank and keep things where they are. My biggest reason is that I don't like how difficult it is to fix things when something goes wrong, or do basic maintenance. This is an early Eta, which means that the fuel filter is clamped to the frame underneath the brake booster. The way it's arranged right now is bothersome to me and I just want to make it better.

    If you read all that and you have any constructive criticism, I appreciate any insight. I'd like to do this properly and safely. I do not intend on playing games with fuel.

    #2
    Originally posted by flumph View Post
    Ok, this might be a long post...

    After much headscratching, I've come to the conclusion that the gas tank in my '84 Eta is full of rust (and god knows what else). This has destroyed both of my fuel pumps and likely blocked much of the hard fuel line under the car. I have a new set of injectors and a known good regulator, and an inline gauge tells me that I am not making enough fuel pressure. Relative to manifold pressure, I'm only getting about 2 bars with a 3 bar regulator. This is bad. If I try to autotune on my MS3, it wants to run a VE of 65 at idle to try to compensate for the lack of fuel feed.

    So, I want to install a fuel cell, an inline pump and mesh filter, and a new regulator. I'm planning on buying everything from Summit because their main location is very near where I live. This car, for now, is strictly a street car with a stock engine and stock suspension. Here's my plan:
    • A 12 gallon Jaz fuel cell with 70-10 sending unit (fits in spare tire well)
    • Pre- and post-pump fuel filters
    • 35-70psi adjustable pressure regulator
    • AEM 385 Lph inline fuel filter
    • Appropriate vent fittings and check valves


    I plan on cutting out the spare tire spindle mount and setting the cell in the spare tire well padded with some dense foam, and strapping it down with some steel bands. Before I spend a whole bunch of money on parts, lines, and fittings, I have a few questions for this fine community. I appreciate any pointers you can give me. I've done some research, but ultimately I've never done this before.
    • I've read in multiple places that "fuel pumps are meant to push, not pull," and that you should ideally mount the fuel pump below the bottom of the cell's sump. I've read elsewhere that you can mount the pump up to 18" above the sump with no bad effect. I'm more comfortable with this arrangement because should a line break or a fitting leak, it won't just piss all the fuel out. What is best practice here?
    • The outlet of the fuel pump and the inlet of the regulator that I've selected fits -6 AN lines. The factory fuel rail has an integrated regulator and a barb fitting for our familiar 8x13mm fuel line. What is an effective way to attach these -6 AN lines to the inlet and outlet of the fuel rail? If my math is correct, the ID of a -6 AN line should be right around 8mm, give or take 10 thou or so. Is it acceptable to just hose clamp the feed line onto the barb fitting on the fuel rail? As for the return line, can I just run it through a factory regulator with the pressure reference line disconnected? I see that Nuke Performance makes fuel rails for the M20 that feature proper -6 AN fittings (and are quite pretty), but I am unclear on how these are intended to be mounted. Has anyone installed one of these before?
    • Is it foolish to route the feed and return lines through the driver's compartment of the car? I've seen mixed opinions on this. For that matter, is the spare tire well a safe location for a fuel cell? I'm not terribly concerned with the shifted center of mass for now. I'm fully expecting to give up trunk space, and I'm fine with this.
    • Tank foam or no tank foam? PVC wiffle balls? This is only a street car for now.


    You might ask why I don't just get a new OEM tank and keep things where they are. My biggest reason is that I don't like how difficult it is to fix things when something goes wrong, or do basic maintenance. This is an early Eta, which means that the fuel filter is clamped to the frame underneath the brake booster. The way it's arranged right now is bothersome to me and I just want to make it better.

    If you read all that and you have any constructive criticism, I appreciate any insight. I'd like to do this properly and safely. I do not intend on playing games with fuel.
    1.) Mount the fuel pump below the tank, let gravity send fuel to the pump. Running a pump dry kills it. You mentioned that rust killed your other two pumps, I am willing to bet it was running them dry as fuel is the lubrication.

    2.) They make -6AN male adapter to the 5/16 fuel rail: Earls part#165056ERL

    3.) Keep the gas line out of the car. First for safety, second you may not pass inspection for track events. A fuel cell in the truck is 'safe' because you have a fire wall between you and the fuel tank. Late 60s mustangs basically have this setup, the trunk floor is a gas tank.

    4.) Add the slosh control as you need it (since that is easy), get it running for now.

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      #3
      I’ve actually considered doing nearly the same setup with my 89 325is. The fuel tank is fuel of junk and rust, and I feel more comfortable running a fresh fuel cell, where it’s easier to deal with as needed. Following for enlightenment.


      Certified welder, fabricator, and structural steel estimator.
      Sent from my iPhone using Tapatalk

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