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Ernest,
Looks like a well thought out design. I believe the secret is keeping all
fuel lines likely to accumulate any significant amount of heat from the
engine/exhaust/etc highly pressurized. That is the way the recent
"returnless" automobile EFIs are keeping vapor lock from happening. Some
have a ECM function which rapidly changes the fuel pressure to compensate
for certain variables they do not even require a pressure regulator, Others
apparently just set the pressure high - like 65psi and use an intake
regulator to keep it at that pressure.
Ford converted the 4 cylinder trucks to a returnless fuel system in 1998.
This system uses a single high-pressure pump in the tank, and an in-tank
pressure relief valve that opens once fuel line pressure reaches 65 psi
controls fuel pressure. Excess fuel is released out of the relief valve and
back into the tank. Fuel moves from the pump through a single plastic line
to a filter mounted on the driver's side frame rail, then up to the fuel
rail on the intake manifold. Lines in these systems use all spring-style
connectors. This system will not allow fuel rail pressure to exceed 65 psi
because of the pressure relief valve, so if your planned boost levels are
going to put your needs above this level, you'll need to convert to a return
style fuel system.
Page 2 of this pdf has a diagram of the Toyota returnless system as well as
a description.
http://www.autoshop101.com/forms/h42.pdf
A description of the Neon returnless system
Here's the basics.
a.. How the System is designed to work:
a.. The Neon uses a returnless fuel system, fuel is pumped up from the
tank to the injectors without using a return line. This means that all the
fun stuff like pressure control is handled under the middle of the car at
the fuel tank.
b.. The fuel pump is mounted in the tank and pushes fuel up out of the
tank at a full 130psi. There is only one pump unlike a lot of EFI systems
which use a "lift" pump to get fuel out of the tank and then another to
boost the pressure up to spec.
c.. In all 1st generation Neons and in the PL2000 until the 2001 model
year the pressure at the fuel rail is regulated at 49psi. The regulator is
always fitted in or on the tank at the pumps outlet.
d.. For the 2001 models (and across the whole Chrysler range) the fuel
pressure was bumped up to 58psi. Apparently there were no other changes
made so it is possible to swap regulators.
e.. All the fuel systems have a in-tank filter mounted to the end of the
pump. This is known either as an inlet strainer or as a fuel filter. It
can be changed - but you will need to drop the tank to change it. Here's a
pic taken by Emilio and posted to the Neons.org boards. The part number for
this filter (well for a 1999 DOHC but they all interchange in PLASTIC TANKED
cars) is "04897416".
You'r moving along rapidly
Ed A
Ding! Ding!
Class is now in session. I have my pen and paper in hand, ready to take
notes.
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