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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