>Tom-
>
>Where can we learn the "few tricks of relay circuit". This sounds like a very
>effective
>technique!
Yes... but if I reply to the list it does defeat the idea!
Still having a SECOND switch for a fuel pump does work rather well.
Most roadsters have mechanical fuel pumps, but having the electric
provides an extra measure of theft security.
For safety reasons, and electric pump should have a cut off switch provided
by an oil pressure switch. If you are in an accident, which usually stalls
the engine, it will turn off the electric fuel pump. Ford uses inertia
switches, which can be found cheapy in wrecking yards, and will also do the
same in case of an accident or rollover.
You can also get a "tank switch" that is a solenoid operated fuel switch to
select from different fuel tanks. If you wire it, so the default is to
draw AIR (i.e. no second tank) it would also provide the same function.
[HINT: Both fuel inlets can come from the same tank, but a large restrictor
in the 'off' position of the fuel switch will limit severally limit fuel
flow... engine will not be able to maintain more than idle speed!] This
works well with the stock mechanical fuel pump.
The control relay, for either an electric pump or the the fuel valve,
can be wired in a "latch and set" mode. You basically use the relays
switched power to turn keep the relay on once set. This will allow use of
a momentary switch to "latch" the relay in the on mode. If you do not close
the momentary switch (which is well hidden) the relay will not remain
energized.
For those on the list who do NOT have a basic understanding of electricity
and electronics, some of these comments will not make sense. Don't worry
about it, but you could still wire in a hidden switch to ground the ignition
points when set (prevents anyone from hot wiring the car, and driving off
with it).
With a fuel cutoff (electrical or mechanical), they can start the car and
drive a few blocks before the car stalls. Advantage is they are usually
out on the street, and a little more suspecious.
Also if someone tries to steal your car, but doesn't get it out of your
driveway it is vandalism. If the start and drive your car, but only get
a block or two, it is Theft. Police, and insurance companies, handle the
two differently.
Oh, I use fusible links on my roadster. If there is a direct short, it will
blow the fusible link. Only time this caught me off guard was after leaving
the roadster at the airport long term parking (dumb place to park a roadster!).
Got back late, and forget to do something... yep, melted the fusible link
and I had no power to the starter solenoid. Took less than a minute to
realize what I had done... and was on my way in another few minutes.
Don't worry... when I sell a car, all the extra goodies are removed. Pity
the new owner who "latches" the horn on full time, rather than set the
fuel pump relay!
For the creative you should have some ideas to work with.
Cheers,
Tom Walter
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