Fuel pressure - EFI vs CIS

["Graydon D. Stuckey" <graydon@apollo.gmi.edu>]

On Mon, 26 May 1997 WARATAP@aol.com wrote:

> Interesting.  When my fuel pump on the '90 V8Q started to get noisey, I
> decided to replace it and the dealership gave me the new "updated one" a year
> (or is it two now?) ago.  Has a special plastic cage carrier, black plastic
> housing, and is about a third the size and 1/4 weight of the original typical
> in-the -tank audi fuel pump. Similar to an oversize windscreen washer pump.

Wow, electric motors are progressing very well indeed.

> No complaints (extremely quiet), but does anyone know the fuel pressure
> output of this pump?  My guess is that it's significantly lower due to the
> V8's EFI system, which is notably different in its fuel pressure needs than
> CIS.

Actually, the fuel pressure and flow needs of an EFI system are very 
similar to the CIS.   I used the stock 5000 fuel pump in my car with 
the EFI swap.   I have a regulator in my fuel rail that maintains 3.5bar 
(about 52psi) and so far, my fuel delivery has been very consistant.  
Most pumps of this sort will generate 100+ psi to a dead head.   The 
important thing is how many gallons per hour it will pump at the 
operating pressure, since that is the limiter for hp.

You might be able to see a stamp on your pressure regulator indicating 
how many bar it is set to.   That is one way to tweek a stock EFI car BTW 
- you can increase the fuel pressure slightly to increase the fuel flow a 
little.   I have a big fuel pressure gauge in the shop that I can attach 
to any fuel rail which has a service port.

Later, Graydon D. Stuckey 

"Cool name man!" - Jay Graydon   :-)