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Thread: Injector pump return line

  1. #1
    Join Date
    Apr 2017
    Location
    Port Macquarie
    Posts
    6

    Injector pump return line

    Just hooking up a veggie oil system to my Hilux 2003. This could be a dumb question butI have seen systems that just loop the return line back into the feed line. Can anyone tell me do you have to install a return line for the veggie oil along with solenoid valves switching it on/off so you are not contaminating the different fuels? I was under the impression that the return line relieved excess pressure from the injector pump and looping it would lead to damage? Any clues? thanks.

  2. #2
    Join Date
    Apr 2011
    Location
    Lismore NSW
    Posts
    321

    Re: Injector pump return line

    Hi yendor,

    Have fun with your first conversion, If I was you, I would keep both systems separate, so yes one return for the Veg and one return for Dino. There will be some minor cross contamination but that's almost impossible to avoid. you can loop the veg return back into the Veg fuel line, just keep in the air after filter changes in mind, it might take a while to get that out if your loop is too long. I have learned that too short is not the best either. good luck, you'll work it out!
    1990 Toyota Hilux LN106 with ATG 2 tank system (sold after running 150.000 ks on mainly WVO)
    1993 Toyota 75 Series with 1 HZ engine both 75l factory tanks and a custom 170l under tray tank.
    200.000km 80% on bio 10% on WVO 10% on dino,

    "him who never made a mistake, made no discovery either"


  3. #3
    Join Date
    Dec 2007
    Location
    South Australia
    Posts
    1,141

    Re: Injector pump return line

    Yes you need two separate systems but you can loop them. I have run looped diesel and looped veggie for the last 10 years or so. See here how I deal with air in the system. http://www.biofuelsforum.com/threads...g-issues/page2
    Johnnojack
    4WD Isuzu Jackaroo 3.1 170,000km on WVO,(2017) 2 tank home built system 6 solenoids. Mk. 9 version. Improvements under investigation

  4. #4
    Join Date
    Nov 2005
    Location
    Tasmania
    Posts
    510

    Re: Injector pump return line

    All my engines that have return lines are looped, and they are not separate. I plumb them in just before the throw away filter, that way when switching to bd/dino, it flushes the filter of veg oil. On my truck it is a little different, the return line goes back to just before the veggie tank as it is all metal until that point and was ion a hurry to do the conversion when i got it. When on dino, the return does go into the veggie tank so it gets a bit of dino or bd into it. The BD tank never gets contaminated with veggie. Have thought of changing it, but no problems so far so have left it and it's been over a year like that.

  5. #5
    Join Date
    Apr 2017
    Location
    Port Macquarie
    Posts
    6

    Re: Injector pump return line

    Quote Originally Posted by Bueff View Post
    Hi yendor,

    Have fun with your first conversion, If I was you, I would keep both systems separate, so yes one return for the Veg and one return for Dino. There will be some minor cross contamination but that's almost impossible to avoid. you can loop the veg return back into the Veg fuel line, just keep in the air after filter changes in mind, it might take a while to get that out if your loop is too long. I have learned that too short is not the best either. good luck, you'll work it out!
    Thanks for that, it means that i will have to buy 2 more solenoid valves and run a return line to the veggie oil tank but i am not keen on putting the injector pump under any unnecessary pressure. I took the return line off and ran it into a container and it seems to pump over a litre a minute at idle so i was worried about that pressure being looped back on itself.
    Thanks for all the help.
    Yendor.

  6. #6
    Join Date
    Sep 2005
    Location
    WA
    Posts
    4,124

    Re: Injector pump return line

    Your test
    I took the return line off and ran it into a container and it seems to pump over a litre a minute at idle so i was worried about that pressure being looped back on itself.
    was about FLOW, not PRESSURE.

    The injector pump is not under any pressure from looping the return line!
    There may be a fuel lift pump (usually for inline IPs) or not, This does not impact on the above statement.
    Fuel goes into the IP and a variable portion (dependent on throttle setting) is sent to the injectors. The remaining fuel is passed to the return line.
    If the return line is connected to the fuel line going into the IP, then that fuel becomes part of the fuel going into the IP.
    If the IP has a fuel lift pump, then I recommend that the return line be looped before the fuel lift pump (tank side of lift pump). This is to prevent leakage from any injector return line hoses (eg on Mercedes diesel engines)
    Last edited by Tony From West Oz; 26th April 2017 at 10:22 PM. Reason: spelling and
    Life is a journey, with problems to solve, lessons to learn, but most of all, experiences to enjoy.

    Current Vehicles in stable:
    '85 Mercedes Benz W123 300CD Turbodiesel single tank using 95% used cooking oil and 5% to 10% misfuel (where someone had filled diesel vehicle with petrol).
    '06 Musso Sports Crew Cab. Running on used cooking oil with 5% to 10% misfuel.
    Toyota Camry Hybrid - (Wife's Car)

    Previous Vehicles:
    '90 Mazda Capella. (2000 - 2003) My first Fatmobile. Converted to fun on veggie oil with a 2 tank setup. Died when supercharger stuck at max boost for weeks. Stretched head bolts.
    '80 Mercedes 300D. 2 tank conversion [Sold]
    '84 Mercedes 300D. 1 tank, no conversion. Replaced engine with rebuilt OM617A turbodiesel engine. Finally had good power. Donor for current Fatmobile coupe. (body parted out and carcass sold for scrap.)
    '99 Mercedes W202 C250 Turbodiesel (my darling Wife's car)[sold]
    '98 Mercedes W202 C250 Turbodiesel (my car)[sold]
    Parts Car C220 1993 All body panels, headlights, interior engine and ECU available.


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  7. #7
    Join Date
    Dec 2007
    Location
    South Australia
    Posts
    1,141

    Re: Injector pump return line

    Save yourself the trouble of installing another fuel one back to vege tank. Exactly as Tony says above.
    Johnnojack
    4WD Isuzu Jackaroo 3.1 170,000km on WVO,(2017) 2 tank home built system 6 solenoids. Mk. 9 version. Improvements under investigation

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