Vehicle fuel system voltage regulator

Discussion in 'The Projects Forum' started by smokeshow, Aug 17, 2011.

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  1. smokeshow

    Thread Starter New Member

    Aug 17, 2011
    I am working on a fuel system for the newer GM vehicles. It exploits the flexibility of the programming of the vehicle's ECM to control the fuel injectors based on various fuel pressures in the fuel system. I have a second pump in parallel with the original pump that activates under high load situations where more fuel is desired.

    My problem now, and I half expected it, is the pressure surge when the second pump activates. Desired fuel pressure is 60psi. It jumps to around 80psi after the 2nd pump activates. When fuel demand increases enough, the pressure settles back to 60psi, but the vehicle experiences a rich spike because the ECM cannot control the fuel injectors quickly enough to compensate for the pressure surge. I tried to get a voltage reading off of the original pump so I'd know what to supply to the second pump, but I could never get a solid reading for some reason. I thought at one point I saw 8.5 volts or so. I figured I'd see what it does and cross that bridge when I got there. Well here I am!

    So, what I'm thinking is put a voltage regulator in series with the supply wire to the second pump to manage the amount of voltage that the 2nd pump receives. Input voltage would be about 14V, the voltage that the vehicle's alternator supplies. Input voltage may have a +/- 1 volt swing. Max current that the pump will draw is 20A. I would like to be able to control output voltage of the regulator from 6-12V. I looked on this site and on others for a high current voltage regulator, but I couldn't find any schematics for a regulator that supplies over 1A. I was hoping someone here could make a suggestion for me? Thanks :)
  2. SgtWookie


    Jul 17, 2007
    Well unfortunately for you, our Terms of Service prohibit discussions on a number of topics, including a blanket "Automotive modifications" ban, which includes your topic.

    All we can do is suggest that you keep your vehicle professionally maintained as it was delivered from the dealer, as at that point in time it had to be in compliance with all regulations/laws in the locale where sold.

    Modifying your vehicle in the manner you have done will cause excessive emissions, which is a violation of emissions controls regulations, and may cause you to be subjected to heavy fines.

    If you feel that you must pursue such modifications, you will need to inquire on other forums that permit discussion on such topics.

    A partial list is in this thread:
  3. smokeshow

    Thread Starter New Member

    Aug 17, 2011
    Well thats unfortunate. So much for the detailed description you guys ask for in all the other threads. Should have kept it to myself...
  4. someonesdad

    Senior Member

    Jul 7, 2009
    Confucius say "Man who read TOS first not fly into hillside and bang head".
  5. Jaguarjoe

    Active Member

    Apr 7, 2010
    Jaguar has done that for years with their XJ"R" and XK"R" vehicles. Nuth'in new here.
  6. smokeshow

    Thread Starter New Member

    Aug 17, 2011
    Careful now, giving me advice could get you busted. Wouldn't want me to do anything dangerous that might affect
  7. t06afre

    AAC Fanatic!

    May 11, 2009
    I also find the total ban on automotive electronics. Just foolish. But as long this is the rule we can not do much about it. besides accept it. A modern fuel pump is quite complicated. So I am not sure regulating the voltage is a very good idea at all. It can be that it has onboard control circuits on board. So feeding a lower voltage may be far from ideal. I suggest you ask around in car tuning forums, to hear what they suggest. They will probably know more than we do in here. If you need help with some electronics. Feel free to ask questions in this forum. But do not say it is for a automotive project. If asked tell a white lie and say it is for a garden fountain, or whatever.
    jj_alukkas likes this.
  8. jester84

    New Member

    Aug 19, 2011
    Have you thought of doing something like putting an inline regulator/ relief that would lift at 62 psi or so and allow the excess fuel to be returned to the gas tank.

    This would allow you to start and stop the pump as needed, and maintain the pressure. I'm assuming there is regulator/relief would be able to have the proper accumulation and blowdown parameters for the application.
  9. debe

    AAC Fanatic!

    Sep 21, 2010
    Most fuel injected vehicles shoud have a pressure regulator on the fuel rail with a return line to the tank. The prob with 2 fuel pumps runing is it cant cope with the volume of fuel flow. The fuel pumps are brush type DC motors, the best way to controll them would be with PWM.
  10. jester84

    New Member

    Aug 19, 2011
    Depending on the fuel system though it may be a non-return type. I ran into this putting an LS1 into a BMW... BMW had a return style system, Ls1 didn't. I added the regulator after the stock pump and hooked up the return line to the regulator output back to the tank.. granted the stock pump was too small
  11. bertus


    Apr 5, 2008

    I am closing this thread as it violates AAC policy and/or safety issues.

    6. Restricted topics. The following topics are regularly raised however are considered “off-topic” at all times and will results in Your thread being closed without question:

    • Any kind of over-unity devices and systems
    • Automotive modifications
    • Devices designed to electrocute or shock another person
    • LEDs to mains
    • Phone jammers
    • Rail guns and high-energy projectile devices
    • Transformer-less power supplies
    This comes from our Tos:
    Terms of Service
    There will be enough sites where automotive questions can be discussed :
    Member selected automotive forums

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