Dave,
You may be correct on the G factor rating, but isnt this what all the chating
is about,
if in fact of a wreck everybody wants a postive way to kill power to the fuel
pumps.
These fuel injection inertia switches can be mounted anywhere on the vehicle,
can be a
safe way to kill power to fuel pumps. And Like you say these are triggered by a
small
amount of G rating. And the driver in case of a wreck can point his attention
more to
bracing for impact or keeping his hands where he needs then instead of trying
to pull a
cutoff switch, lets the inertia switches do the work. Being in several wrecks
myself, my
mind isnt there going thru a checklist, im more curious on whats happening, but
those
that have been in a wreck, it goes by to damn fast to react sometimes anyway.
So in my
mind those inertia switches are a postive unit on any car. Just my thoughts
though, and
who am i anyway to question???
Jonathan Amo
dahlgren wrote:
> You hit the reason why in your question.. "Sensitive little switches.."
> These respond to some fairly low G ratings..If i bump a car in the
> parking lot youare liable to set some of them off. So if when pushing
> someone off I bummp you a bit it may trip. And to my knowledge these are
> not adjustable to suit racing needs. if my memory is correct I had heard
> that a 5 or 10 mph hit is like 5 g's...The info i remember is from the
> old State Police crash simulator stuff of years gone by that was used to
> remind people why they need to wear a seat belt.
> Dave Dahlgren
>
> Jonathan Amo wrote:
> >
> > Just out a curiosity why cant or dont people use the fuel inertia cutoff
>switch for
> > the fuel pumps as all fuel injection cars have, in event of a wreck these
>sensitive
> > little switches will automatically trip and cutoff power to fuel pumps?
> >
> > Jonathan Amo
> >
> > Joe Amo wrote:
> >
> > > Dave, thank you very much for the tech info. It is very much
>appreciated to
> > > hear such details, I am sure at times many refrain from expounding about
>a
> > > particular matter, but many of us truly soak up the discussions from the
>variety
> > > of sources on this list
> > > Thanks again, we are all the wiser (and safer) for it
>Joe :)
> > > :) :)
> > >
> > > dahlgren wrote:
> > >
> > > > With an EFI System if it is installed correctly and the controller is
> > > > worth anything at all should control the fuel pump. The normal mode of
> > > > operation is as follows..
> > > >
> > > > switch on:
> > > > power up injector relay
> > > > power pump relay for 8 to 10 seconds to prime the fuel lines
> > > > shut off pump relay
> > > >
> > > > start position:
> > > > crank engine
> > > > if RPM is greater than 100 power up pump relay
> > > > engine starts
> > > >
> > > > run position:
> > > > keep injector relay powered up
> > > > check for RPM if less than 100 shut off pump relay
> > > > else power pump relay
> > > >
> > > > switch off:
> > > > shut off injector relay
> > > > when RPM drops below 100 shut off pump relay
> > > >
> > > > Do this over and over until you are tired of racing today, ran out of
> > > > fuel, or blew the engine up....
> > > > A very quick check to see if this is installed correctly is to turn the
> > > > switch to the on position..If the fuel pump runs for the 5 or 10 seconds
> > > > and then stops it is installed correctly..If your EFI does not do this
> > > > there is one of a few problems.
> > > > #1 you installed or wired it incorrectly bypassing all the safety
> > > > methods built in to it.
> > > > #2 You intentionally thought you knew more than the engineers that
> > > > designed the system and put in a manual switch.
> > > > #3 the system is so unsophisticated that it ought to be pulled from the
> > > > market as it is a safety hazard..
> > > > This method works for every production car that i am aware of that has
> > > > not been tampered with. The reason they(the auto companies) do it this
> > > > way is to avoid the exact problem we are discussing. Fuel pump running
> > > > in a crash or with the engine off. They do also use an inertia switch to
> > > > shut off everything in the event of a crash but this is NOT suitable for
> > > > a racing car..
> > > > The simplest way for the tech guys to check for a correct installation
> > > > is to have the driver have only one switch to make the car run. Have the
> > > > driver power it up and listen for the electric pump. It should run for
> > > > the 5 to 10 seconds then stop. If it does not do this send them to the
> > > > end of the line and have them fix it correctly. The installation will be
> > > > safe when it passes this test..
> > > >
> > > > Dave Dahlgren
> > > > Engine Management Systems..
> > > >
> > > > BTW I am not reading from a user's manual on this.. I have installed
> > > > tuned and designed EFI for the last 15 years...and write computer code
> > > > that is inside EFI units that are for sale today....
> > > >
> > > > John Beckett wrote:
> > > > >
> > > > > Chris
> > > > >
> > > > > With EFI you really need a separate fuel pump shut off switch.
>The Cut
> > > > > Off Switch we have been discussing on the list, in my opinion, should
> > > > > disconnect everything electrical on the vehicle. But its not a
>replacement
> > > > > for an individual fuel pump switch.
> > > > > The worst thing you can do is put in some sort of barrel valve to
>stop
> > > > > fuel flow only. The problems created...increased line pressure and
>current
> > > > > draw...will make things much worse.
> > > > >
> > > > > John Beckett, LSR #79
> > > > >
> > > > > ----- Original Message -----
> > > > > From: "Chris R Harris" <yesford@clear.net.nz>
> > > > > To: "land-speed" <land-speed@autox.team.net>
> > > > > Sent: Tuesday, February 08, 2000 1:17 AM
> > > > > Subject: Re: Cut off
> > > > >
> > > > > > List and especially Dan Warner,
> > > > > > I already have a
>battery
> > > > > > isolating switch on the dash of my roadster in easy reach of the
>driver
> > > > > and
> > > > > > will install a second in series in a location like the back of the
>car
> > > > > like
> > > > > > the consensus suggest. My additional question is, with EFI, will
>the dash
> > > > > > mounted battery isolater switch fill the requirement for a fuel
>shut-off.
> > > > > > The dash switch will shut-off all current to the electric pump, EFI
> > > > > > electronic control unit and ignition, or do I still require a
>positive
> > > > > > mechanical barrel valve style fuel shut-off.
> > > > > > Chris Harris C/GR #397 New Zealand.
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