[Vwdiesel] Braking -- engine etc. ( injection pump as a brake ? )

[Sandy Cameron]

At 08:03 AM 1/9/04 -0800, you wrote:

>The fuel entering pump at inlet banjo is many many many times the volume
> fuel consumed by the engine.   I do not know for shure why the excess fuel
>is taken all the way back to the tank ( on rabbits 1980 to 1984)  maybe it is
>to make for cooling of pump.  ??? what do fellas think.      Hagar.

I think there was a conscious decision to design the fuel system to work in
cold weather (Like we have here today, -25c, -10f) The generous fuel flow,
engine block heat, thrashing governor weights, etc. warm the fuel which is
returned directly into the pickup well in the tank, creating a local warm
spot to heat fuel for pickup, and get it through the screen without plugging
with wax. I was out scooting around in the 87TD last night and noticed it
hesitated as I banked off the freeway onto the sharp curve of the exit ramp
at speed, but it quickly recoverd once straight and level again. 
Could it have sloshed a glob of suspended wax into the pickup line from a
colder part of the tank? Who knows.

Also, in hot weather, the extra fuel flow would help cool the pump a bit, as
having the fuel TOO hot is not a good thing either.

On models from 1990, the return fuel passes through a small thermostatic
widget on top of the filter that diverts some of the warm fuel through the
filter when it's cold, to prevent wax plugging of the filter element.

Sandy