I couldn't agree more. And this also explains some questions people had
about inertia switches, discussed a while back. Thanks Dave.
John Beckett, LSR #79
----- Original Message -----
From: "dahlgren" <dahlgren@uconect.net>
To: "John Beckett" <landspeedracer@email.msn.com>
Cc: <Land-speed@autox.team.net>
Sent: Tuesday, February 08, 2000 9:54 AM
Subject: Re: Cut off
> 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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