[s-cars] Relayed FP

[David Forgie]

Scott: Thanks, I appreciate your comments about use of the larger gauge wire.  I was going to do that
but at the time, I couldn't find wire with insulation that wouldn't get eaten by the gasoline.  I did eventually
get some teflon-coated wire but I have yet to install it.

One comment that I have to argue is the use of a spade-type inline fuse.  That is exactly the same fuse
 type as the OE fuses in the fuse panel.  I have not had any fuse failures in 13+ years of UrS ownership so
 I am  not concerned about that fuse failing (hasn't in 7+ years so far).  I presume that you have different 
experiences with these fuses.

Dave F.

----- Original Message -----
From: Scott Justusson <qshipq at aol.com>
Date: Monday, November 14, 2011 10:21 am
Subject: Re: [s-cars] Relayed FP
To: forgied at shaw.ca, s-car-list at audifans.com

> 
>  Good information, but also know that there are several
> 300+ATWHP cars running no relay mod, hence my suggestion it may
> not 'solve' anything.  To your writeup itself, when I did 
> one of these mods to a 400ATWHP S car, I also replaced the stock 
> 14guage wire to the actual pump in the tank, with 10 guage wire 
> from the aux relay pin 87 feed, and added a redundant ground of 
> 10guage wire to the pump as well.  Likely massive overkill, 
> but I also do this routinely on the urq external pumps.  
> Also, I don't use a crappy failure-prone 'inline' fuse for this 
> mod, I usually mount a aux fuse block under the rear seat, which 
> also gives a couple slots to add 12v feed to the headlights, 
> which can also suffer light output from lower than battery voltage.
> 
> Cheers and HTH
> 
> Scott J
> Relay mods aplenty
> 
> 
> 
>  
> 
>  
> 
> -----Original Message-----
> From: David Forgie <forgied at shaw.ca>
> To: s-car-list <s-car-list at audifans.com>
> Cc: qshipq <qshipq at aol.com>
> Sent: Thu, Nov 10, 2011 8:52 pm
> Subject: [s-cars] Relayed FP
> 
> 
> Scott:  As detailed in the link to one of my DIYs that JaMu 
> provided(http://forums.quattroworld.com/s4s6/msgs/24327.phtml) 
> there was a significant improvement in the
> voltage at the fuel pump when the OE fuel pump relay was simply 
> used to trigger another relay sitting
>  beside the battery and 4 ft from the fuel pump instead of 
> allowing current to flow forward from the
>  battery, through the fuel pump relay and all the way back 
> to the fuel pump.  This was done to help
>  eliminate significant pinging on certain unnamed (okay, 
> Pastore) "RS2" software that Sean D. and I were
>  experiencing on Chevron 94 shortly after we RS2's our AANs 
> back in 2004.  The new relay definitely
>  helped to decrease the occurence and severity of the 
> pinging.  The real solution for us was better
>  software  (MRC Stage 3 in my case and Dahlback MTM in 
> Sean D's case). 
>  
> It must have been a good idea if 034 commercialized it.  ;>)
>  
> Dave F.
>  
> Scott J expounded:
>  
>  >The urq pump is also relayed from the factory, and this 
> is a standard issue mod, not based on theory,
>  >it's a known practical application of voltage at the pump 
> vs pump output.  The main reason to do this
>  >relay mod is 17 feet of wiring between the factory FPR 
> and the fuel pump can create quite a voltage
>  >drop.  Easy to test this improvement, if battery 
> voltage = voltage at the fuel pump = no improvement. 
>  >IME with Audis, rarely does the battery voltage = voltage 
> at the fuel pump.  And the difference in fuel 
> >pump output is quite significant when voltage drops:
> >http://performancefuelsystems.com/images/clip_image004_001.jpg
> >
> >I won't go so far as to say it will *solve* anything, but low 
> voltage at the fuel pump can create running
>  >problems under boost.  The good news is with many 
> Audi batteries mounted under the seat, this is a
>  >simple and effective mod.
> >
> >HTH and my .02
> >
> >Scott J
> >Relayed fuel pumps aplenty
> 
>  
>