At 04:34 PM 2/2/2003, Red Raevyn wrote:
>...but if you ask me it's simply another piece of Ford engineering brilliance.
Actually, it makes a lot of sense.
My first experience with an electric fuel pump shut-off switch was a 1978
Toyota Celica (furrin' car). If the oil pressure dropped too low, an oil
pressure switch would open and shut off the fuel pump. If you happened to
go around a freeway ramp kinda fast with a low tank of gas, the fuel pump
pickup would starve, the engine would start to die, the oil pressure would
drop, and the fuel pump would just quit pumping. Usually, this required
coasting around the ramp until the fuel leveled out in the tank so you
could re-start the engine.
My next experience with an electric fuel pump shut-off was a 1979
Volkswagen Rabbit (furrin' car built in Westmoreland, Pa.). The fuel pump
relay contained an electronic circuit that monitored the tachometer signal
from the ignition coil. If the distributor points stopped opening and
closing, the fuel pump stopped. I don't recall ever having a problem with
this, though the presence of a tach signal at the fuse block (where the
fuel pump relay was mounted) made it pretty easy to install a tachometer in
low-buck Rabbits that didn't come with one.
I don't know when Ford started installing impact switches in their fuel
pump circuits. The assumption is that if you hit something hard, thus
damaging the front of the vehicle, you probably want the fuel pump to stop
delivering a flammable liquid to a part of the car that may have hot stuff
or sparking stuff. I also don't know how many other manufacturers use these
impact switches.
By the way, the Ford switch used to be mentioned by part number in the
vehicle preparation rules for the SCCA Trans Am series. The switch was
required on Trans Am cars in order to stop the fuel pump if the car was in
an accident.
Also, by the way, Ford usually mentions the switch in the owners manual
explaining what it does and how to reset it. Of course, vehicle owners
manuals are not high on anybody's top ten reading list.
Bob...
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