[Shotimes] Engine Starting Speed

[SHO GOS]

The SHO like most fuel injected engines uses a pressurized fuel system. It
only takes a couple of seconds to get the system up to pressure. The fuel
pump puts out 190 l a min. That's a lot of gas for the size of the lines we
have. This is why they have a pressure regulator and a fuel return line. The
pressure in the lines should be a constant, that's what the regulator is for
and if there is more fuel and pressure in the system than is needed it is
returned to the gas tank, still under pressure.

Put a gauge on your rail and you'll see that when you turn on the key the
system is pumped up to operating pressure. This is one reading that you take
when you are doing an injector leak test along with injector bleed down rate
and the amount of current your injector is drawing.

If your pressure leaks off after shut down and then you turn the key back on
the system is repressurized. If the engine cranks for a longer period than
normal then your cylinders have raw fuel in them, like a flooded engine
condition but not as bad as fully flooded. If you do have a weak injector
you'll notice the engine cranking longer when the engine is cold.

Where is it written that the PCM shuts off the fuel pump under 120 rpms?


----- Original Message -----
From: "Kevin & Cheryl Airth" <clubairth@cajunnet.com>
To: "SHO GOS" <shogos@earthlink.net>; <shotimes@autox.team.net>
Sent: Sunday, December 15, 2002 11:08 PM
Subject: Re: [Shotimes] Engine Starting Speed


> Yes exactly but it does NOT run until they are pressurized it is only time
> based and that may be causing the problems. You can prove it by cycling
the
> key. The pump will run for exactly the same amount of time every switch of
> the key, regardless of the pressure in the fuel rail.  As you said even
when
> the engine stops running there is still some pressure left in the fuel
rail
> but not enough to run the engine. Think about it, If your pressure leaks
off
> after shutdown. Then you start the engine from a very low pressure
> situation, it might run rough or even stall until the pump is running
> continuously. Fuel pumps usually fade out and do not give a nice clean
> failure which would feed this even more.
> .
> .
> .
>
>
> > My fuel pump runs longer than 1 second when I turn on my key, more like
3
> > and it does pressurize the fuel rails. Disconnect your fuel pump, start
> your
> > engine and let it burn all of the fuel left in your rail. I'm willing to
> bet
> > that there's still pressure and fuel left in your rails. To test this
for
> > yourself, smack that fuel pump cut off switch on your trunk, start your
> > engine and run it until the engine dies. Now pop your hood, remove the
cap
> > from the shrader valve on your fuel rail and press in the valve and see
if
> > you don't get sprayed by gas.
> >
> > I've cleaned several SHO fuel rails and injectors and every time I hook
up
> > the hose to the fuel rail shrader valve I have a shop towel on the other
> end
> > of the hose so the gas doesn't go all over the engine. After every thing
> is
> > hooked up I turn on the key to allow the pump to run so I can dump that
> > pressure into the cleaner can just in case the can's internal pressure
is
> > low.
> >
> >
> > > This is common to all EEC-IV vehicles. If the rpm is below 120 rpm the
> PCM
> > > will not let the fuel pump run. So that is the lower limit, if the
> starter
> > > can not spin the engine at least 120 rpm it will never start. Remember
> > that
> > > when you turn the key on it does NOT pressure the fuel system to 39
PSI.
> > It
> > > ONLY runs the fuel pump a fixed length of time. Usually 1 second.
That's
> > why
> > > when your fuel pump is weak you need to cycle the key several times.
> With
> > > only running 1 sec. it might take 5-6 cycles to build enough pressure
> for
> > > "instant" start.