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Thread: Injector pump return line

  1. #1
    Join Date
    Apr 2017
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    Port Macquarie
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    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
    395

    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 HDT conversion, 75l factory tank and a custom 170l under tray tank. (Retired with 680.000ks on the clock mostly running on BIO and on WVO)

    2006 Landcruiser Troopcarrier 1HZ with DTS Turbo Kit, 170ltr long range tank currently not converted, running on B100

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  3. #3
    Join Date
    Dec 2007
    Location
    South Australia
    Posts
    1,244

    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 200000km on WVO,(2020) 2 tank home built system 6 solenoids FPHE, heated filter fuel line and tank pickup for thicker oil. Mk. 9 version now and no changes planned as trouble free.
    Mercedes W201 190D 1986 model: 2 tank system, bigger fuel line from tank, no heat exchanger, electric pump for diesel 22000km so far

  4. #4
    Join Date
    Nov 2005
    Location
    Tasmania
    Posts
    538

    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
    12

    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
    4,377

    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:
    '06 Musso Sports 4X4 Manual Crew Cab tray back.
    '04 Rexton 4X4 Automatic SUV
    '2014 Toyota Prius (on ULP) - Wife's car

    Previous Vehicles:
    '90 Mazda Capella. (2000 - 2003) My first Fatmobile. Converted to fun on veggie oil with a 2 tank setup.
    '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. Engine donor for W123 coupe. (body parted out and carcass sold for scrap.)
    '85 Mercedes Benz W123 300CD Turbodiesel
    '99 Mercedes W202 C250 Turbodiesel (my darling Wife's car)[sold]
    '98 Mercedes W202 C250 Turbodiesel (my car)[sold]
    '06 Musso Sports Crew Cab well body. [Head gasket blew!]
    '04 Rexton SUV 2.9L Turbodiesel same as Musso - Our Family car.
    '06 Musso sports Crew Cab Trayback - My hack (no air cond, no heater).

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  7. #7
    Join Date
    Dec 2007
    Location
    South Australia
    Posts
    1,244

    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 200000km on WVO,(2020) 2 tank home built system 6 solenoids FPHE, heated filter fuel line and tank pickup for thicker oil. Mk. 9 version now and no changes planned as trouble free.
    Mercedes W201 190D 1986 model: 2 tank system, bigger fuel line from tank, no heat exchanger, electric pump for diesel 22000km so far

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