EFI Fuel System using a Surge Tank
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EFI Fuel System using a Surge Tank

  1. #1
    Member StreetMoto's Avatar
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    Default EFI Fuel System using a Surge Tank

    Guys,
    My EFI Blown 540 is getting closer and I need to figure out the fuel system for the Rayson Craft. I have saddle tanks and I'd like to be able to switch from one to the other while using the high pressure elec. fuel pump.


    I've been told elec. fuel pumps do not like to suck, so the idea is to use a mechanical fuel pump to draw from a saddle tank, fill a surge tank that will gravity-feed the elec. hi-pres. pump.

    Here's the idea so far, looking for feedback. Thanks!

    • One elec. fuel selector for feed lines from saddle tanks
    • From tank selector to a mechanical fuel pump (to suck fuel out of selected saddle tank)
    • Mechanical pump to a small (1 gal) surge tank.
    • return fuel line from surge tank, back into the feed line between tank selector and mechanical fuel pump (this way I don’t need a separate fuel selector to return fuel back to the same saddle tank)


    This should create the continuous fuel needed to keep the surge tank full (I hope )

    Now for the high pressure side.

    • feed line from bottom of surge tank to high pres elec. fuel pump
    • from hi pres elec fuel pump up to fuel rails etc, then fuel pres. regulator.
    • From fuel pres regulator, back to surge tank (high pres. return line)


    I'd end up with 2 sets of feed and return lines (4 lines total) on the surge tank, 2 high pres. and 2 low pres.

    The only issue I can think of is I might need to prime the surge tank if I ever let the tanks run dry because it might take too long for the mechanical fuel pump to fill it up while cranking the motor over with the starter. Once it’s full, would a good high-flow mechanical fuel pump flow enough to keep the surge tank full? I've been told the motor will produce somewhere around 1,000 HP.

    Hope this makes sense! Thanks in advance for the help guys.

    Sean

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    Highaboosta Unchained's Avatar
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    You have a few options that would work good,

    1) If your fuel tanks have the fuel lines coming out the bottom of the tanks you could mount one electric pump on each tank and that would work good. The pump would have fuel all the time and never would need to draw it from the tanks.

    2) A separate submersible fuel pump in each tank would work good. They are cheap and will always be in the fuel supply.

    3) A small submersible pump in one tank can be used to put pressure in the fuel rails to get the motor started, Once it's started a mechanical pump will take over and work good. This is the setup I have with an Aeromotive cam drive pump.

    The mechanical pump has the most capacity but will not put out much pressure at cranking rpms.
    Large electric pumps have a reputation of not lasting real long in a cruiser boat.

    The negative to electric pumps is that they put out the same volume of fuel at idle as at high RPM.
    Mechanical pumps flow more as the rpm increases.

    You will need a return line all the way back to each tank.
    You could operate one or both electric pumps from the saddle tanks. There should'nt be a need for a selector switch.

    I've tried a few variations of fuel pumps with EFI.
    Feel free to give me a call
    Mark 616 813 7237

    Twin Turbo 1800 HP V-Drive lake boat

    http://s621.photobucket.com/albums/t...t=MAH05771.mp4

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    Or Seth, either one Budweiser's Avatar
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    The way you've described your plan sounds like it may work. It's just a whole lot of extra $tuff and clutter. If that's your game, go for it. I prefer simple myself.

    I'd make it super simple and run a mechanical pump from Race Pumps.

    It requires a dead head style regulator, which would eliminate the need for a fuel return line. It will probably need a small electric pump to prime like the crank driven option, but it's not needed once the engine is running. Have the ECU run it for 5 seconds on start up, or even wire it to a little momentary button/switch on the dash, or wire it up to the starter terminal (via a relay and dedicated fuse)....

    Easy, reliable, & clean instalation

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    Or Seth, either one Budweiser's Avatar
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    On second thought, if you have an overflow line off the 1 gal tank drain to the suction side of the mechanical pump in your plan, there is a real good chance the pump would suck more air through that line than fuel from the tanks. Better to come up with some sort of float/needle/seat arrangement instead. I know I saw a pic of one like that a few years back. Pretty sure it was here on performanceboats.

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    Member StreetMoto's Avatar
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    Quote Originally Posted by Budweiser View Post
    On second thought, if you have an overflow line off the 1 gal tank drain to the suction side of the mechanical pump in your plan, there is a real good chance the pump would suck more air through that line than fuel from the tanks. Better to come up with some sort of float/needle/seat arrangement instead. I know I saw a pic of one like that a few years back. Pretty sure it was here on performanceboats.
    That was one of the concerns I had, I knew it would require priming the system if it every ran empty. Might need to go the mechanical pump with elec primer. Thanks!

  8. #6
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    Quote Originally Posted by Unchained View Post
    You have a few options that would work good,

    1) If your fuel tanks have the fuel lines coming out the bottom of the tanks you could mount one electric pump on each tank and that would work good. The pump would have fuel all the time and never would need to draw it from the tanks.

    2) A separate submersible fuel pump in each tank would work good. They are cheap and will always be in the fuel supply.

    3) A small submersible pump in one tank can be used to put pressure in the fuel rails to get the motor started, Once it's started a mechanical pump will take over and work good. This is the setup I have with an Aeromotive cam drive pump.

    The mechanical pump has the most capacity but will not put out much pressure at cranking rpms.
    Large electric pumps have a reputation of not lasting real long in a cruiser boat.

    The negative to electric pumps is that they put out the same volume of fuel at idle as at high RPM.
    Mechanical pumps flow more as the rpm increases.

    You will need a return line all the way back to each tank.
    You could operate one or both electric pumps from the saddle tanks. There should'nt be a need for a selector switch.

    I've tried a few variations of fuel pumps with EFI.
    Feel free to give me a call
    Mark 616 813 7237
    Thanks Mark, I'd like to take you up on that call. I've heard your boat is a rocket and I'd rather get some direction from someone who's gone through this process a couple times already. Talk to you soon!

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    Highaboosta Unchained's Avatar
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    Yeah it's a handful, if I had it to do over again I would use 1/2 the size engine I did.
    I am contemplating a winter project with a stock Lexus V8 engine and a single S475 turbo. EFI and E85 fuel of course.
    It would be easy to make 1000 hp and that should be plenty for a lake boat.

    Twin Turbo 1800 HP V-Drive lake boat

    http://s621.photobucket.com/albums/t...t=MAH05771.mp4

    Quote Originally Posted by Trigger View Post
    No one cares about your buddies old antiquated garden hose technology.
    Quote Originally Posted by MAXIMUS View Post
    I think I could run more boost but it's a real hand full right now

  10. #8
    gn7
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    Quote Originally Posted by Unchained View Post
    Yeah it's a handful, if I had it to do over again I would use 1/2 the size engine I did.
    I am contemplating a winter project with a stock Lexus V8 engine and a single S475 turbo. EFI and E85 fuel of course.
    It would be easy to make 1000 hp and that should be plenty for a lake boat.
    WHAAAAAAAAT?? No 5.3 LS? Put a Nissan in that thing and you'll be working on it more than driving it. Put a STOCK LS in it straight from a truck, 1000 easy HP on pump 87 octane and you can hand it down to your great grandchildren.



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    Senior Member ap67et10's Avatar
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    Sean,

    I have done almost exactly what you are thinking. Here is the surge tank I designed. It has a feed and return on the back side from and to the side tanks. It has the gravity -12 on the bottom and a -6 return from the regulator on the top side. The breather is fake, just to match the identical look of the puke tank on the other head. I had this on the dyno and it worked great. The biggest difference is that I had custom side tanks made with 1/2 return ports, so I will either run the 6 port fuel switching valve, or run 2 manual 3 way valves to select the feed and return tanks. It is more plumbing, but it makes the system function much better and you don't need to worry about air being a problem. Also I run an Aeromotive electric carb pump as the transfer pump PN 11213. I figure with the regulator dumping into the surge tank, all the -12 and -10 lines with the 1" fuel rails, and the .75 gal surge tank I will have more than enough fuel to cover any WOT runs I make. If you plan on some extended WOT runs you may want to ensure you transfer pump can keep up.

    How is that galaxy coming? Hadn't heard back from you on that one.


    Andrew







    Last edited by ap67et10; 07-30-2013 at 03:22 PM.

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