Page 1 of 3 123 LastLast
Results 1 to 10 of 28

Thread: Using separate lift pump and IP for a quick purge

  1. #1
    Join Date
    Dec 2005
    Location
    Perth Western Australia
    Posts
    936

    Using separate lift pump and IP for a quick purge

    Amongst the threads that were lost from last year is one from me which contained a diagram rightfully called the most complicated setup ever. I've moved on a bit now and have another setup to bewilder and confuse - but heck, it works for me.

    My aim then, and now, was to get a quick and effective purge by using the separate lift pump and injection pump of the Landcruiser. It seemed a lot of extra purging to have to clear out the lift pump, filters and heat exchanger - well over a litre of capacity I imagine. The only diesel I carry is in a ten litre tank under the bonnet, so I needed to minimise purge times to extend the useful range of the start up tank.

    The common 2H engine has the same lift pump as my 12H-T but I think more recent models have the lift pump and injection pump combined in the same unit, making these suggestions irrelevant for most Landcruisers - tho maybe not other vehicles with separate lift/injection pumps. The mechanical Lift Pump specs are 29psi at 900mls per minute.

    Input to the lift pump is 12mm which only feeds Canola into the lift pump. Output of the lift pump to
    Twin fuel filters in parallel to
    Flat plate heat exchanger to
    Three way motor driven valve with outputs going to the injection pump or returning to the Canola tank so the Lift pump is never dead headed.

    This setup allows the canola to be flowing through the filters and heat exchanger right up to change over time, ensuring hot oil is right at the changeover valve, approx 100mm from the injection pump when needed at changeover.

    My IP has a high return flow out the back of the injection pump and I control the direction of this flow with a second three way motor driven ball valve to either loop the return to the inlet of the lift pump, or back to the diesel start up shut down tank. On looped return the filters are heated by the return flow, reaching 75C after a while, then the HE adds an extra up to 10C before the canola heads into the IP once again.

    The problem was to find a way of getting diesel into the injection pump. This is achieved by an electric fuel pump and gas solenoid to stop any backflow, T'd into the Injection pump feed line just after the canola fuel selection valve mentioned above. Initially I used an old bronzed square style Facet type pump producing 4psi but it got a leak so I replaced it with a new black plastic Facet Posiflow pump at 4 psi.

    This ran the engine apparently without problem, but I found I got no flow out the back of the injection pump and this was a problem as I relied on good flow to purge the pump quickly. I found out my IP had a bypass valve built into it that relied on 23 psi to crack the valve and let fuel out the return line. I bought a VL Commodore EFI pump from a wreckers which worked for a while whilst testing, then developed a leak so I took the plunge and bought a brand new EFI pump to match the Commodore pump.

    Now the diesel is sucked out of the 10 litre jerry can under the bonnet, into the pump, through a CAV filter, through the injection pump and returns 2.4 litres a minute back into the diesel tank. Pressure at the injection pump is a perfect 2 bar or 29 psi so the IP is full of fuel at good pressure for it to run properly, and indeed it does; I've noticed a power increase on diesel since I added this pump.

    My purge process now is two stage with ten seconds (about 400mls) of purging the lines and IP whilst on looped return so I do not dump 100% canola back into the diesel tank. Any extra diesel flows into the lift pump, filters and FPHE diluting the canola and minimising the risk of fat blockages on cold mornings. After ten seconds, the diesel is switched to return to the diesel tank for the remainder of the one minute shutdown cycle to allow the injector lines to clear canola through to the injectors and minimal canola diluting the diesel in the start up tank.

    More testing will allow me to work out the optimum time before the diesel starts to come out the return line and this can be dialed into the electronic control box.

    The dual stage purge is only possible with two three way valves, and not possible with a single 6 way Pollak.

    Tim
    Toyota Landcruiser 1988 HJ61 Manual Wagon
    12H-T turbo Direct Injection.
    Twin Tank setup runs on 100% WVO after warm up. 30 plate FPHE with 80C output, 12mm fuel lines
    Start up and shut down electric fuel pump feeds IP direct.
    Front 4WDSytstems Lokka, Rear ARB airlokka for quick escapes up sandhills. Performance GTurbo with 600mm FMIC gives 450nm @ 1700rpm at 20psi boost.

  2. #2
    Join Date
    Sep 2005
    Location
    WA
    Posts
    4,344

    Re: Using separate lift pump and IP for a quick purge

    Tim,
    Have you considered using the gas solenoid to return the majority of the veggie to the veggie tank, via the veggie supply line?
    This would only work if the veggie pump were in the engine bay, or allowed free flow in the reverse direction.

    I will see If I have a diagram of this layout and post it here.

    Tony

  3. #3
    Join Date
    Dec 2005
    Location
    Perth Western Australia
    Posts
    936

    Re: Using separate lift pump and IP for a quick purge

    Hi Tony,

    When on diesel, the vege is pumped by the lift pump through the filters, heat exchanger and all goes back to the vege tank via the normal return line as I think you are suggesting.

    When switched to vege, the vege is looped back into the inlet side of the lift pump so the lift pump gets hot oil, as do the filters and the heat exchanger input.

    Currently the gas solenoid is simply used to ensure no vege flows back through the CAV filter, the diesel electric pump and into the diesel tank, when under pressure from the lift pump.

    The attached diagram might help.



    Tim
    Last edited by Tim-HJ61; 19th March 2008 at 07:55 PM. Reason: Add diagram
    Toyota Landcruiser 1988 HJ61 Manual Wagon
    12H-T turbo Direct Injection.
    Twin Tank setup runs on 100% WVO after warm up. 30 plate FPHE with 80C output, 12mm fuel lines
    Start up and shut down electric fuel pump feeds IP direct.
    Front 4WDSytstems Lokka, Rear ARB airlokka for quick escapes up sandhills. Performance GTurbo with 600mm FMIC gives 450nm @ 1700rpm at 20psi boost.

  4. #4
    Join Date
    Nov 2007
    Location
    Victoria
    Posts
    445

    Re: Using separate lift pump and IP for a quick purge

    Hi Tim-HJ61,

    That's a way cool system even if it's complex. How did you find out about the VL fuel pump psi or was it just a guess/try it at the time?

    It will be a great system when you have it all set up/automated, look forward to hearing more,

    God bless froggo.
    HJ45 Landcruiser Troopy
    Home made 2 tank system
    Blending in main diesel tank
    SVO/WVO Converted 18/01/08
    http://www.biofuelsforum.com/svo_users/3667-hj45_troopy_conversion.html

  5. #5
    Join Date
    Dec 2007
    Location
    South Australia
    Posts
    1,239

    Re: Using separate lift pump and IP for a quick purge

    Tim looking at your diagram it looks like the return from the diesel control valve sends vege back to a tee near the vege tank during flushing. Is that right. If so I think you would be better off directing that flow (which contains a mixture of veg and diesel which is increasing in concentration of diesel every second) back to the vege circuit before the FP heat exchanger. That way you will charge the FPHE and filters with a blend of vege and diesel enabling easier switching to vege after starting and minimising the problem of the IP having to deal with a slug of cold vege which is downstream of the FPHE and therefore not heated.
    This cant work if your lift pump wont allow return flow. You could move the lift pump to near the IP., after all it is a lift pump.
    Johnnojack

  6. #6
    Join Date
    Dec 2005
    Location
    Perth Western Australia
    Posts
    936

    Re: Using separate lift pump and IP for a quick purge

    Johnnojack
    Quote Originally Posted by Johnnojack View Post
    Tim looking at your diagram it looks like the return from the diesel control valve sends vege back to a tee near the vege tank during flushing. Is that right.
    Yes, though I call it the return control valve. It sends the fuel either to the T before the lift pump to be sucked into the lift pump, Filters and FPHE in a looped return setup OR returns the fuel to the diesel tank.

    Quote Originally Posted by Johnnojack View Post
    If so I think you would be better off directing that flow (which contains a mixture of veg and diesel which is increasing in concentration of diesel every second) back to the vege circuit before the FP heat exchanger. That way you will charge the FPHE and filters with a blend of vege and diesel enabling easier switching to vege after starting and minimising the problem of the IP having to deal with a slug of cold vege which is downstream of the FPHE and therefore not heated.
    This cant work if your lift pump wont allow return flow. You could move the lift pump to near the IP., after all it is a lift pump.
    Johnnojack
    I did a test yesterday to see how quickly the output of the injection pump changed colour from canola to diesel. Given some time lag of my 14 yo old flicking the switch and clicking the stopwatch, and my reaction time - I'm pretty confident of this time being 3 seconds. Add a couple of seconds to make sure and we get five seconds for the diesel to flow through the injection pump and out to the return control valve. One, two, three - bingo. Pretty cool eh! Now I understand the fuel has to purge through the injector lines and injectors too, but I am very happy I have cleared all the canola out of the IP in quick time with a blast of diesel and have found a one minute turbo timer setting to be pretty right for good starts in the morning. They come with a burst of black smoke indicating diesel, not canola.

    Johnnojack, I agree with what you're saying and that is actually what happens pretty much. The fuel is flowing into the lift pump all the time, as it sucks it up from the tanks. So the diesel, or canola, that is fed into the looped return T piece just prior to the inlet, is going to get drawn straight into the lift pump and distributed as you say.

    A significant consideration is that I only have 10 litre jerry can of diesel for start up shut down purging. I can't have too much filling the filters and HE unless necessary and given the EFI pumps at 2.4lpm, my 10l tank can empty in a few days of usage which is a nuisance.

    You've made me realise tho that if I T the flow from the Canola control valve back to close to the lift pump pickup whilst the system is warming up, then I will heat the Lift pump, filters and FPHE faster with warmed canola.


    Froggo
    That's a way cool system even if it's complex. How did you find out about the VL fuel pump psi or was it just a guess/try it at the time?
    Thanks mate. EFI fuel pumps are generally 40 to 60 psi, I think BrianW told me and it was backed up when I started to review the various pump options. Facet type pumps only go to 4 or 12psi, not enough to crack the bypass valve in the 12h-t injection pump. How did I find that out? I rang/emailed a couple of injection pump places and asked them what pressure they tested 12H-T injection pumps at and why - 23 psi.
    My Gregory's manual told me the output specs of the lift pump - 2 Bar or 29 psi at around 1 litre a minute.

    I bought and built a Jaycar kit to reduce the voltage to the pump - DC motor controller kit - if the volume and pressure was too much but haven't needed to use it.

    Given the EFI pump seems to be working okay and the pressure has not gone over 2 Bar on my gauge, it would seem the bypass valve is opening at 23psi as it should and can handle the volume of the EFI pump - ie the pressure is not rising above the specs of the lift pump so all must be good inside the injection pump.

    Tim
    Toyota Landcruiser 1988 HJ61 Manual Wagon
    12H-T turbo Direct Injection.
    Twin Tank setup runs on 100% WVO after warm up. 30 plate FPHE with 80C output, 12mm fuel lines
    Start up and shut down electric fuel pump feeds IP direct.
    Front 4WDSytstems Lokka, Rear ARB airlokka for quick escapes up sandhills. Performance GTurbo with 600mm FMIC gives 450nm @ 1700rpm at 20psi boost.

  7. #7
    Join Date
    Dec 2005
    Location
    Perth Western Australia
    Posts
    936

    Re: Using separate lift pump and IP for a quick purge

    An update from today.

    Given the short time it is taking to purge the canola from the injection pump, we decided to not add the complexity of a timer circuit to delay the switching of the return valve.

    Instead we installed 2 x 4700uf capacitors and the do the trick just nicely. So if anyone else has their valves controlled by relays, this may be of interest to them. We have two three way valves driven by electric motors and controlled separately in order to delay the return switching over to diesel so to not put canola into the diesel tank.

    The capacitors work as a micro battery, soaking up the current whilst the power is on. When the power is off, they discharge their power. A relay coil does not use much power, and the capacitor kept the coil excited for some small periods of time. We started off with some spare 47uf and 100uf to test the theory then went about finding bigger and bigger capacitors until it worked.

    I do not know the resistance of the relay coil, but 1x 4700uf capacitor kept the relay powered for approx 1.6 seconds, 2 of the same for 3.2 seconds and three of the same in parallel delayed for 4.8 seconds. These were the largest 16v electrolytic capacitors we could easily find at Jaycar electronics.

    The electric solenoid - gas tap - failed in todays high temperatures and I have replaced it with a 1/8" one way valve that cracks open at 6psi, so now there is one less electronic component to fail.

    Hope this idea helps someone.

    Tim
    Last edited by Tim-HJ61; 27th February 2008 at 12:53 AM.
    Toyota Landcruiser 1988 HJ61 Manual Wagon
    12H-T turbo Direct Injection.
    Twin Tank setup runs on 100% WVO after warm up. 30 plate FPHE with 80C output, 12mm fuel lines
    Start up and shut down electric fuel pump feeds IP direct.
    Front 4WDSytstems Lokka, Rear ARB airlokka for quick escapes up sandhills. Performance GTurbo with 600mm FMIC gives 450nm @ 1700rpm at 20psi boost.

  8. #8
    Join Date
    May 2008
    Location
    UK
    Posts
    9

    Re: Using separate lift pump and IP for a quick purge

    I know this is an old thread, but I like very much the proposed conversion sceme. I have only 1 question.

    It looks like the oneway valve is the only component that stops the diesel flowimg constantly into the IP. Tim, you said you had to replace the faulty solenoid valve with a simple one way valve with 6psi opening presure.

    I would like to know is it sufficient to stop the diesel breaking through and mixing with the Veg Oil (Canola)? It looks like you have 2 identical lift pumps 1 pumping diesel the other Canola into the same T-piece and the only difference in the diesel route is that 6psi valve.

    Did you have to work out the 6psi value by try/error? Because the pumps may be identicle but the routs are not - different lenght, presence of more filters and heat exchanger in the Canola route -this might leed to more presure loss on that route...

    Please share your experience. Thank you.

  9. #9
    Join Date
    Feb 2007
    Location
    Perth, Australia
    Posts
    134

    Re: Using separate lift pump and IP for a quick purge

    Quote Originally Posted by allfriends View Post
    I would like to know is it sufficient to stop the diesel breaking through and mixing with the Veg Oil (Canola)? It looks like you have 2 identical lift pumps 1 pumping diesel the other Canola into the same T-piece and the only difference in the diesel route is that 6psi valve.

    Did you have to work out the 6psi value by try/error? Because the pumps may be identicle but the routs are not - different lenght, presence of more filters and heat exchanger in the Canola route -this might leed to more presure loss on that route...
    Since Tim has gone walk-about I will take the liberty to answer this question (as the use of the one way valve was my suggestion).

    Both pumps put out approx 25psi and therefore opening the one way valve is no problem. The diesel pump is a petrol electric EFI pump and it is switched off when on WVO so that the one way valve is definitely closed due to the WVO lift pump pressuring the other side. There can be no flow of diesel back into the tank.

    The factory lift pump constantly filters and recirculates the WVO since it is mechanical and operating while the engine is running. When the 3 port valve changes position the WVO is sent either back to the tank or to the IP.

    Tims design started out of necessity, but it has resulted in a very good system with fast purge and relatively simple operation. I am very impressed with it and would recommend it to anyone with a similar system, but it is not very common.

    regards
    B
    Toyota Landcruiser 80 Series 1990 VX Ltd - 12HT powered- diesel for run-in period (no longer 1HDT).
    190L vege oil LR tank and 90L diesel, Vormax, 30 plate FPHE, two automated 3-way ball valves with delay to prevent mixing on purge.

  10. #10
    Join Date
    May 2008
    Location
    UK
    Posts
    9

    Re: Using separate lift pump and IP for a quick purge

    Thanks Brian. Now it all makes sence since you told me the lift pump on the diesel branch goes off when the system is switched to Canola.

    Please have a look on my slopy drawing and tell me if it will work. I have done a little change to Tim's configuration in order to get the oil heated quicker and shorten the Diesel return route as well.

    Please tell me if I have done some rookie misstake. The idea is still on paper and if someone has tryed it and foud out that it does not work there is no point me trying it.

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •