[Vwdiesel] Fueling screw on VE pumps. --( Rabbits )

LBaird119 at aol.com LBaird119 at aol.com
Tue Jul 20 22:24:59 EDT 2004

> WHAT?   does it do ? :    It operates about the same as when you adjust the 
> float
> level on a gasser.

  Not even close sorry!
  It's nothing like setting the float level.  It most like adding a little 
travel to the throttle.  Back out that screw, put slack in the cable or 
push the floor mat under the pedal and you'll get the same results 
except your idle will remain the same with the latter two.
  Setting the float level down can lead to starvation, where the engine 
doesn't get enough fuel to run - doesn't happen when backing out 
the screw unless idle drops too far.  Setting float higher can cause 
flooding or slightly richer mixture due to more "head" above the jet 
but that's pretty minimal.  The flooding would equate to a bad injector.
  "At idle, the air-to-fuel ratio may be greater than 100:1; even at top 
speed, the mixture never approaches the comparatively rich stoichiometric 
air-to-fuel ratio of approximately 14.5:1 that is common to spark-ignition
engines."  (Bentley Manual: Fuel system - Diesel section.)
  Basically, as load increases, A:F ratio decreases in order to maintain 
speed.  Simply decrease the A:F ratio and you lower the speed of 
the engine, if you're at limit.  Below limit, the car will be going at a 
speed commensurate with the amount of fuel being injected.
  It looks more like if you want to lean out your engine, slow down.  
As long as you're not at the limit of what the pump's set at, turning 
the screw back will only limit your maximum acceleration.  It 
won't make things any more lean at cruise.
  Maybe I'm all wet but that's the way I've seen it.

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