Conversion to EFI : Fuel system

[Bruce Plecan]

-----Original Message-----
From: Mitch <ozyman at employees.org>
To: diy_efi at efi332.eng.ohio-state.edu <diy_efi at efi332.eng.ohio-state.edu>;
Date: Thursday, March 18, 1999 5:14 PM
Subject: Conversion to EFI : Fuel system


The purpose of the JTR book is to tell the first timer how to do, so that it
works first time thru.  I'd suggest that you do it his way the first time.
Get it up and running.  Then experiment.
  Mount pump below gas tank height.
  Never inclose a fuel pump in a non oem "housing".  They make fuel-air
bombs.
The warm fuel issue really is nothing you'll have much control over.  If you
min the amount of fuel recycled, all the fuel lines are hotter than need be.
In high demand the Hot fuel (in the rails) will be used rather quickly.
The fuel in the tank is what it's going to be, based on fuel pump capacity,
and how much is recycled.  Really not much to do here since the pump needs
to be large enough for WOT fuel demand.
  Follow someones lead and just use their info., first time thru.
Just getting the installation "stock" is enough work.  You'll have lots of
time to try and improve it.
IMHO
Bruce
>
>Anyway, after reading Mike Knell's books, as well as Hartman's, I have
>decided the most challenging aspect of the swaps, for me, will be
>retro-fitting the fuel systems on mechnical pump cars.  Instead of getting
>custom-made fuel tanks, I'd like to implement the dual-pump external fuel
>reservoir system described in Knell's TBI/TPI book.
>I am working this out step by step.  To discuss this with you folks and
>some other buddies, I have put some drawings up at:
>There are a number of vexing issues.
>1. Where should the main return line go?  Knell's book suggests back to the
>remote fuel reservoir, but I was concerned about heat.  I was thinking that
>it would be best to return the fuel that has been to the intake manifold
>back to the large tank.  If you return it to the small tank, some of it
>goes back to the manifold for further heating.  If you return it to the
>large tank, there is no such problem.
>Now, my guess is it doesn't hurt to do it this way, but I was wondering
>what the logic is for returning back to the remote reservoir.  I asked
>Knell about this, and he said if you don't return to the reservoir you can
>suck air if you run out of fuel from the main tank.  But if you run out of
>fuel you run out of fuel; returning to the remote reservoir will maybe give
>you another minute or so of life.
>2. What is the air pressure in the main fuel tank?  Is it positive or
>negative?  I am concerned because I thought the charcoal canister works
>with positive air pressure in the fuel tank, and I don't see how it can be
>positive in my diagram.  I have been assured from several quarters it is
>about 1-2psi positive, but was looking for an exlpanation of this, since
>you are always sucking fuel out of the tank.
>3. Does it matter whether the pumps are above or below the fuel tank?  I
>was assuming it didn't, but I recently read a book which suggested the
>pumps should be below the tank.  This would be difficult for me to set up
>in my car.
>4. Just some general stuff: I am concerned about noise.  One idea I had was
>to make this an assembly and mount it on rubber mounts, like motor mounts.
>I was definitely considering some kind of case or cabinet (steel (like an
>old toolbox) or plastic), but I am concerned about the hazard of buildup of
>fumes, and also cooling for the pumps.  I'd need some way to vent the
>thing.  I wonder whether it would be overkill to build some cooling/venting
>fans into the cabinet.
>So if you folks have any advice or ideas on this, please let me know.  I'll
>continue to refine the diagrams as I nail this down.  After fooling around
>with the stock TBI Malibu, I expect to convert the 327 in my garage to TBI
>or port injection the diy_efi way.
>Cheers,
>Mitch Barrie
>Goat Hill, CA