[s-cars] Fuel pump ideas for IA Stage III+ UrS6

Scott Houser swhouser at gmail.com
Tue Feb 17 11:23:05 PST 2009

Hi. Noob here. Car is a 1995.5 S6 Avant, 82K miles. Upgraded to an IA Stage
III+ {Stage 1 in other nomenclature, with a 3 Bar transducer} chip 8 months
ago. Recently replaced two dying coils with an 034 HO Coil kit, and have
since experienced a number of issues. Not related to the coil kit, we now
know. Seems like bad timing and luck! Overboost, found a boost leak, MAF
issues and running rich, to now running very lean {17:1 A/F} when in high
boost. We've sourced at least two problems to a kinked fuel line {since
fixed}, and a faulty fuel pump. The FP was replaced about a year ago with a
stock 43mm {019G} Bosch pump. Evidently, it's not pulling enough fuel. My
experience in the past has been that pumps would get noisy and then die. Not
this. Swapped in the pump that I saved as a spare, and it runs much better
{not perfect, may be the voltage drop along with an older pump}.  My plan is
to relay a new one to the battery. Question is what pump? I have no plans
for more power. No RS2. I had though that a Bosch 43mm pump was the
appropriate one for my set up. I also assumed that they were all German
built. The failing one is marked "made in Germany".  Is a 60mm  044, or 040
more than I need? Any downside to going that big? Perhaps an 005 is the
solution? I've been reading about a Walbro 255 as an option. Any ideas,
recommendations or experience with this issue? I posted over on AW, and have
just one reply, suggesting to just do the 044 or 040. I'm not sure if I'll
be done for now after the new FP, but I know that it needs replacing as a
next step.
Thanks very much for any input.

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