[s-cars] Can you teach an old fuel pump new tricks ???

[Paul Gailus]

The direct from battery test sounds like a good idea,
but I would still include an in-line fuse close to the
battery positive terminal. Otherwise, a short in or around the
fuel pump could have some undesirable results.

Paul

----- Original Message -----
From: James Murray (QB/EMC) <james.murray at ericsson.com>
To: 'Mark Strangways' <Strangconst at rogers.com>; Dave Forgie
<forgied at direct.ca>; s-cars <s-car-list at audifans.com>
Sent: Tuesday, July 27, 2004 7:12 AM
Subject: RE: [s-cars] Can you teach an old fuel pump new tricks ???


> Just as easy to grap a couple of wires direct from the battery and connect
them to the fuel pump without a relay just to test the theory...if it does
help, I'd look to see why you got line losses before installing new
permanent lines, probably the relay is getting old and tired, and needs
replacing, the contacts might need cleaning or else some connections need to
be tightned.
>
> /Jamu.
>
> -----Original Message-----
> From: s-car-list-bounces at audifans.com
> [mailto:s-car-list-bounces at audifans.com]On Behalf Of Mark Strangways
> Sent: Tuesday, July 27, 2004 8:05 AM
> To: Dave Forgie; s-cars
> Subject: Re: [s-cars] Can you teach an old fuel pump new tricks ???
>
>
> Maybe find someone with a wideband O2 sensor and do some testes at WOT.
> Maybe you don't have fuel issues at all.
>
> Look to the IC, is it clean inside and out.
> If it has some dirt clogging the passages that would account (extra heat)
for the ping.
>
> Mark S
>   ----- Original Message -----
>   From: Dave Forgie
>   To: s-cars
>   Sent: Tuesday, July 27, 2004 3:24 AM
>   Subject: [s-cars] Can you teach an old fuel pump new tricks ???
>
>
>   S-gruppees:   I just want to bounce this off you and see what you
>   think.  Sean Douglas and I are now quite convinced that, based on his
>   fuel pressure readings, his (and my) "new" fuel pump(s) are not putting
>   out enough pressure to the fuel rail at full RS2 (plus) boost levels,
>   e.g. 22 to 28 psi.  We have already noted that when the car is running
>   (and the alternator is running), the maximum voltage at the fuel pump is
>   only 12.5 V and it goes down as low as 11.8 V as the car gets warmer and
>   more boost is requested (by our heavy right feetses).
>
>   So, we have a brain wave:  what if we double relay the fuel pump?  Right
>   now, power goes from the battery/alternator to the central relay panel
>   position 6 under the drivers side dash.  The ignition switch energizes
>   the relay and three contacts are closed.  As far as I can tell by
>   examining the relay (I opened it up) and Bentley, two contacts seem to
>   be for the fuel pump and one seems to be for the O2 sensor heater. .
>   >From there the fuel pump power goes through Fuse No. 17 at the drivers
>   side end of the dash and then it runs ALL the way back to the fuel pump
>   which is located in the fuel tank which sits at the back of the trunk,
>   over the rear diff assembly.  In going  this round the world route, the
>   voltage drops in the order of 1.2 to 1.9 V depending on the load.  I
>   just bet this doesn't help the fuel delivery and pressure situation.
>
>   Now as it happens, the fuel pump is only about 3.5 feet from the
>   battery, through the passenger seat bulkhead.  So I am thinking, what if
>   we use the normal voltage from the existing relay to trigger a second
>   new relay located near the battery and then run a nice thick gauge hot
>   wire from the battery to this new relay and then to the pump.  The
>   intent would be similar to adding relays to the headlights - cut out the
>   line losses and get more juice to the driven object, in this case, the
>   OEM fuel pump. Done properly, this should (hopefully) give us 13.7 ish
>   Volts at the fuel pump with the engine running.   This has to make the
>   fuel pump spin a bit faster and, therefore, I suspect we may be able to
>   over come the existing fuel pressure deficits that Sean has estimated
>   and, therefore, get enough fuel to the engine under full boost that we
>   can start saying "Yeeeee HHhaaaaaah!!!" again (instead of tuning our
>   ears to the dreaded pinging death rattle).
>
>   Anysink wronk mit dis plan?  Any fatal flaws in ze logic??
>
>   The other alternative, the Audi Sport fuel pump, is still suggested to
>   a) not have enough pressure and b) too much flow so this double relay
>   trick seems to be a potential good (and cheap)  solution.  The other is
>   too buy a case of OEM pumps and test each of them and pick the best two
>   of the litter.  Unfortunately, I don't have that much time or money to
>   play that game.
>
>   TIA
>
>   Dave F.
>
>   _______________________________________________
>   S-CAR-List mailing list
>   S-CAR-List at audifans.com
>   http://www.audifans.com/mailman/listinfo/s-car-list
> _______________________________________________
> S-CAR-List mailing list
> S-CAR-List at audifans.com
> http://www.audifans.com/mailman/listinfo/s-car-list
> _______________________________________________
> S-CAR-List mailing list
> S-CAR-List at audifans.com
> http://www.audifans.com/mailman/listinfo/s-car-list