[200q20v] Problems.. where to start? (very long)

C1J1Miller at aol.com C1J1Miller at aol.com
Wed Nov 29 08:20:24 EST 2000

In a message dated 11/29/00 12:19:15 AM Eastern Standard Time, 
knotnook at traverse.com writes:

> How would it get past the injectors unless they weren't sealing between 
>  squirts?
>  At 10:50 PM 11/28/2000 -0500, C1J1Miller at aol.com wrote:
>  >In a message dated 11/28/00 8:07:37 PM Eastern Standard Time,
>  >pwaterloo at compuserve.com writes:
>  >
>  > > The only
>  > >  place it goes in is through the inlet manifold through the injector, 
>  > right?
>  > >  I don't think there is any other place it could leak into the engine.
>  >
>  >Another possible place is the fuel pressure regulator on the end of the 
> fuel
>  >rail; if the diaphram leaks, you'd have fuel flowing into the intake.
>  >Chris

"Fuel Pressure Regulator 

The fuel pump supplies fuel to the fuel filter, then, via a fuel rail, to the 
injectors.  The fuel returned from the injecors is routed through the fuel 
pressure regulator.  The diaphram-type fuel pressure regulator maintains fuel 
pressure at approximately 3 bar (43.5 psi) above the intake manifold 
pressure.  A vacuum line from the intake manifold to the pressure regulator 
is used to transmit the varying intake manifold pressures. 

At idle, only a small quantity of fuel is needed to maintain engine 
operation.  Vacuum from the intake manifold is applied to the diaphram and 
spring in the pressure regulator which allows more fuel to return to the fuel 
tank to maintain the correct fuel pressure. 

When the engine is under full load, the fuel consumption is greater.  
Manifold pressure is increased due to boost pressure from the turbo.  This 
pressure closes the diaphram in the pressure regulator, allowing less fuel to 
return to the fuel tank to maintain the correct fuel pressure. 

When the engine is switched off, the diaphram in the pressure regulator is 
completely closed due to spring pressure.  This creates a holding pressure 
between the pressure regulator and the fuel pump. "

So, get a leak in the diaphram, and gas will go into the intake manifold.

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