[Shotimes] Engine Starting Speed

[Kevin & Cheryl Airth]

> > 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?


If you put a gauge on the test port it will verify exactly what I said. the
fuel pump DOES NOT run until the fuel rail is pressured up. Again this is
strictly a time based event. Get your watch and gauge out to verify this. IT
IS A FACT. Without a PIP signal, the fuel pump will only run in 1 sec
intervals unless the test point is grounded.The 120 rpm comes from the
Probst book on Ford EEC-IV. Page 144.
 Next your cylinders will NOT have raw fuel in them. Again the system knows
not to flood out the engine. After 20 sec. of cranking without engine start,
the injector pulse width is reduced. Starting injector pulse width is
entirely controlled by temperature, coolant and air. If by chance you do
flood the engine, the system even provides for that. Holding the accelerator
to the floor will cut off the injectors completely. Allows engine to draw
only air and flush out the raw fuel.
 When people have to hold down the accelerator to get the car to start and
the engine is NOT flooded. This points to the IAB. Since all starting air is
controlled only by the IAB. If it does not open all the way or is sticky the
engine is starved for air when starting.

 Don't confuse the fact that the pump builds some pressure when you turn on
the key with the fuel pump controlled by the pressure regulator. These are
two different engine operating conditions.

 Next: a weak injector is very easily to diagnose. Simply run the cylinder
balance test and see if any cylinders are weaker than the rest.
.
.