Excerpts from audi: 7-Sep-95 Fuel filters- diesel vs. gas. by
Christopher Bridge@vt.ed 
> the right size, and was thinking about mounting this on the fan housing.  
> The only nagging question is what is inside that little canister?  Will it 
> filter gas as well as diesel?  Is there a problem at the gasket?  All the 
> rest is easy.  Does anyone have any ideas about this one?  Am I crazy?
> 
As far as I know, most diesel cars and trucks run high pressure(25-100
psi) fuel lines from the tank to the injection pump(where the pressure
is kicked up to several thosuand psi).  I'm not sure that you would have
enough pressure to push gas through a diesel fuel filter.  Aside from
that, it sounds like a great idea.  My diesel audi had a drain on the
bottom of the filter, it was amazing how much water collected in there.  

James

My diesel VWs have a single fuel pump, the injection pump.  It does generate
the high pressure necessary on the output side, but on the input side,
genereates enough suction to pull the fuel from the tank up to the injection
pump.  I don't know how strong that suction is, but I don't thing it is real
high.