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Controlling a small fuel pump

Discussion in 'Electronic Design' started by [email protected], Aug 6, 2007.

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  1. Guest

    I have an application where I have 12v dc power to a fuel pump. It's
    pretty small. It only provides about 80psi. I want
    to lower the fuel pump pressure by regulating the voltage to the pump.
    What sort of device or devices would I need to put inline on that
    circuit to allow me to easily turn the pump up and down?

    Will I need to worry about heat dissipation? Heat sinks?

    Basically, I need something like a dimmer switch for lights I guess.

    Thanks for any help.

  2. First, I think you need to prove to yourself that varying
    the average voltage to this pump produces the effect you are
    wanting (lower fuel pressure without damaging the pump). A
    variable DC bench supply would be handy for this experiment.

    If that checks out, you might do a Google search for the key
    words [buck converter tutorial]. Switching buck converters
    reduce voltage by turning the full voltage on and off,
    rapidly, and then averaging those pulses with an LC output
    filter to produce a low loss DC voltage reduction. Another
    nice thing about this approach is that it produces more
    output current than the input current. Pretty high
    efficiency (up to something like 90%) are possible, and in
    the case of a motor or other inductive load, no averaging
    filter may be needed, as the motor may be able to perform
    this function. There are also integrated circuits made that
    may do most of this function with very few additional
  3. Jim Thompson

    Jim Thompson Guest


    It won't.

    Been there, done that, when I outfitted an after-market A/C to a '67
    Toyota, and replaced the mechanical pump with an electric one to clear
    some space on the side of the block.

    The electric pump over-powered the float valve in the carburetor and
    flooded the engine.

    Drove for awhile using a toggle switch to run the pump for a few
    seconds, then drive until the engine began to stumble ;-)

    Ended up adding an inline pressure regulator to force the pump to

    ...Jim Thompson
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