Dave, Jon and others, how about having the inertia switch isolated from the
circuit until
it is armed after push off and "car is under its own power moving on down
course", I know a
little more sophistication with the circuit, but have the driver arm the
circuit after the
push off. Joe :) :)
Jonathan Amo wrote:
> 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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