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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