Trigger to control a big ass fuel pump

Discussion in 'Technical' started by MagicMike, Mar 31, 2016.

  1. MagicMike

    MagicMike Moderator Staff Member

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    Ok, so I have quite a complicated fuel system that needs some tweaking.

    I have a Walbro 460 in tank, a 3L surge tank, a large 42401 Fuelab external pump and a 52901 Fuelab FPR.

    Now I went with these units because my ECU (nistune) does not have capability to control a pump. This pair of pump and reg are made to work together in that the regulator has a PWM output that connects to the pump speed control terminal. The catch is that the manufacturer specifies that the return doesn't go to a (non vented) surge tank, so mine was plumbed back to the main tank. I was expecting that the walbro would fill the surge fast enough to give me some headroom at low load to keep the surge full ready for high load.

    This caused some issues for me where the external was draining the surge tank.

    So the work around for me as I see, is to change the plumbing so that the rail return goes to the surge tank, keeping it full, but then I still need a way to control the external pump speed as it is not recommended to run constant full duty.

    Now, back to the pump speed control... This terminal can take either a PWM or a 0-5v. Also, if this terminal is left open the pump is perma full speed, and it it is earth the pump is perma slow speed (not so slow at about 500+L/hr so I found out).

    Voltage method of control, <0.25V is low speed and >2.5V is high speed.

    I need some way of switching the pump automaticlly as I don't want to have to manually toggle it.

    Option 1 as I see is to switch high/low based on boost or fuel pressure with something like a hobbs switch and a relay (either earthing out or opening the speed control terminal).

    Option 2 is connecting some feedback from the ECU in 0-5v format directly, along the lines of TPS or MAF where low V equals low load and high V equals high load. Unfortunately TPS or MAF voltage scales don't really fit the low 'cruise' V requirement as idle TPS is 0.45ishV and MAF is ~1.3V.

    The first option seems pretty straight forward. The second option tho, are there are any other options that I have overlooked???

    Discuss please.
     
  2. Mitch

    Mitch Has one gear: GO

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    My eBoost2 EBC has a relay output.
    Not sure if this helps in your instance though.
     
  3. MagicMike

    MagicMike Moderator Staff Member

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    Never thought of that. Have to read up on mine
     
  4. SrAfciGeR

    SrAfciGeR Member

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    Output to RPM meter should be 0-5V

    Maybe you need some additional electronics to scale out the outputs to your desire.
     
  5. rob260

    rob260 Moderator Staff Member

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    There's an obvious answer here... You really need an ECU that's capable of running all the gadgetry you've installed
     
  6. MagicMike

    MagicMike Moderator Staff Member

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    I dont have another 2k+ to spend at the moment (if ever again). So close now it isnt funny, could nearly run the pump on perma slow for 98 at least, e85 not quite.
     
  7. stumagoo

    stumagoo Active Member

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    how about getting a vented surge tank to allow the return to go there? or modifying yours so its vented
     
  8. TWIN TERROR

    TWIN TERROR Well-Known Member

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    Why not just get an arduino board off ebay for under $10 then write (or get someone that plays with Arduino)a program that uses the tacho input to vary the speed of the fuel pump. Also Jaycar might already have a kit that does a similar thing. Shouldn't be that hard. Google this arduino fuel pump controller and heaps come up. Anyone that plays with Arduino board will just copy and paste the correct program for you and mod it were you require. Verify it and upload to a board for next to nothing.
    These boards can do anything and they are cheap. Or this might work off the shelf ?
    http://www.ebay.com.au/itm/Aeromoti...819509?hash=item3f5314eb35:g:UsEAAOSwu4BV6cqP

    Cheers
    Dave
     
  9. Fists

    Fists Well-Known Member

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    Do you need the extra flow at anything less than basically wide open? Maybe use a kickdown switch to toggle a relay, or as the switched earth for the controller if the current ratings match up.
     
  10. michaelZ

    michaelZ New Member

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    As Silicon chip magazine authors

    I dabble in microcontrollers and electronics but the guys at this Australian magazine can certainly help you. The Arduino microcontroller can do whatever you want cheaply. I suggest you email them at tech@siliconchip.com.au . Just explain what you need to happen and when. They will probably need specs of the pump or its make and model number of what you want to control. They should be helpful.

    MichaelZ
     
  11. MagicMike

    MagicMike Moderator Staff Member

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    First thoughts were arduino, but then I asked myself if that is complicating something that could be simple?

    Ultimately all i need is a way of switching an earthed signal to an open signal at somewhere between half throttle ish and WOT. All i really want is for the pump to not be flat out all the time. I dont really need full pwm speed control because the reg is a great reg in its own right and i run a fuel cooler so fuel temp is not a great concern (think overcycling).

    Low speed is well sufficient for everything bar WOT really but if it can be full speed prior to WOT that would ensure nothing goes lean through boost transition.
     
  12. ztoy

    ztoy Autospark Evolution

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    Wouldnt it all be simpler just to get an in tank pump that will flow enough to keep the surge full?

    If not, half my car is controlled by arduino, We will be able to work something out.
     
  13. MagicMike

    MagicMike Moderator Staff Member

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    Traditional plumbing (rail return to surge) will keep the surge full easy. Then i just need some kind of trigger for a relay for somewhere between heavy cruise and WOT lol
     
  14. ztoy

    ztoy Autospark Evolution

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    and then surge return to tank of course.


    Using and arduino to read manifold pressure and getting it to output the voltages you need is an easy task. I could knock that up in no time,

    My emmission control in the ls1 zed is controlled by arduino the same way.

    With a little electrickery using a big arse resistor and a relay we may also be able to get your low speed flow rate even lower.
     
  15. Fists

    Fists Well-Known Member

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    Actually, couldn't you just use one of the OEM FPCUs to fire the relay? Plug straight in if you haven't Anti'd your looms. Probably don't even need to change parameters.
     
  16. SrAfciGeR

    SrAfciGeR Member

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    If I understood correctly you need .25v for low speed and 2.5v for high speed.

    Easiest and cheapest solution that you can possibly do is to get two Zener diodes connected of the Tacho signal feeding fan speed controller.

    For the low speed you just get .25V zener diode of the Tacho and feed it to the fan controller.

    For the high speed you just get 2.5V zener diode of the Tacho and feed it to the fan controller.

    As the voltage rises up to the .25v fan wil go low speed, and when it hits 2.5v will switch to high speed.

    Since that is the signal voltage zener diode will be able to cope.

    Now if you need .25v at any given time so your pump runs at low speed, you will then need to get that voltage of Acc relay and (use voltage dividers to get form 14v down to the .25 or there about's)
     
  17. WazTTed

    WazTTed Grease Monkey

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    specialty z run all there dual pump setups via hobbs switches (boost activated)
     
  18. SrAfciGeR

    SrAfciGeR Member

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    If I understood correctly you need .25v for low speed and 2.5v for high speed.

    Easiest and cheapest solution that you can possibly do is to get two Zener diodes connected of the Tacho signal feeding pump speed controller.

    For the low speed you just get .25V zener diode of the Tacho and feed it to the pump controller.

    For the high speed you just get 2.5V zener diode of the Tacho and feed it to the pump controller.

    As the voltage rises up to the .25v pump wil go low speed, and when it hits 2.5v will switch to high speed.

    Since that is the signal voltage zener diode will be able to cope.

    Now if you need .25v at any given time so your pump runs at low speed, you will then need to get that voltage of Acc relay and (use voltage dividers to get form 14v down to the .25 or there about's)
    -
    I had to correct my previous post as I wrote "fan" instead of pump...
     
  19. Chrispy

    Chrispy Pretentious Upstart

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    Look at this. Or worst case this and a Arduino.
     
  20. AndyMac

    AndyMac Better than you

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    Why don't you just use the TPS circuit? 5V is full noise, so 2.5V will be about half way, plenty of safety margin, and will run at slow speed for 90% of your application.

     

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