Re: [DML] She starts (painfully), she runs (mostly), she doesn't go anywhere...

[JP Hindin <jplist2008@xxxxxxxxxxxx>]

On Thu, 20 Jun 2013, Peter Lucas wrote:
> I'm with Elvis on this one.  If you lower the voltage on a dumb motor, the work done does NOT stay the same.  Rather, the pump will produce lower pressure.   After all, when you turn off the switch, the voltage goes to zero.  Does that mean the the current goes to infinity?!

Elvis may be right, there may be a logic flaw in my understanding of how
the fuel pump works.

But I'd never trust advice on electronics from a man with the surname
'Lucas' ;)

 - JP

> On Jun 20, 2013, at 10:38 AM, Elvis <elvisnocita@xxxxxx> wrote:
>
> >
> > Gentlemen,
> >
> > there is nothing inside the pumpt that controls the output power of it !
> > This is a stupid brushed motor that spins depending of the counterpressur that it sees.
> >
> > The unused pressure is transformed into fluid flow by the pressure regulator.
> >
> > And - a higher resistance (bad connector, thin wire, oxydized fuse, melted fuse holder) reduces the current.
> >
> > NO need to believe me, I just make my money with fans - which is nothing else but an air-pump.
> > BTW - powerfull fans do have electronics inside to limit the max speed by PWM - therefore they can keep the power constant. When the voltage goes down - in certain limits - it draws more current.
> > Again - nothing like this in a fuel pump.
> > Yes, I even cut an old pump open to see how it works.
> >
> > Oh another example - the interior fan - it uses resistors to reduce the power, position 1 and 2 don't even require an extra relay...strang if - according to you - the current goes up ?!?!?!? :-P
> >
> > Have fun ;-)
> > Elvis & 6548
> >
> > --- In dmcnews@xxxxxxxxxxxxxxx, Ian <texas.twister@...> wrote:
> > >
> > > Ditto!
> > >
> > > Ian Yanagisawa
> > >
> > > On Jun 18, 2013, at 12:53 PM, JP Hindin <jplist2008@...> wrote:
> > >
> > > >
> > > >
> > > > On Tue, 18 Jun 2013, Elvis wrote:
> > > > > This is a very strange theory, that a lower voltages kill something and draws more current.
> > > >
> > > > This one I /can/ answer - the work of the pump doesn't change, so it's
> > > > fixed - the laws of physics state that by lowering the voltage, the
> > > > amperage must go up (Volts x Amps = Watts). This damages the pump because
> > > > it's not designed to run at higher amperages, which would require it to be
> > > > more sturdy with heavier duty wiring and stators, thus it burns out.
> > > >
> > > > > Anyhow - is the piston in the fuel distributor stuck ?
> > > > >
> > > > > Push the air metering plate down and you 'll see.
> > > >
> > > > I'll check this also, thank you.
> > > >
> > > > I've never actually dug into the engine bay - I only redid the tank - so
> > > > I'm a little gunshy of tearing off covers and digging into it. I guess I'd
> > > > best get over it and get cracking.
> > > >
> > > > - JP
> > > >
> > > > > --- In dmcnews@xxxxxxxxxxxxxxx, Ian <texas.twister@> wrote:
> > > > > >
> > > > > >...
> > > > > > The low voltage ends up requiring more amperage to run the pump. This will eventually burn out the pump. There have been several threads on this issue. ...
> > > > >
> > > > > >
> > > > >
> > > > >
> > > > >
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