diagnosis needed

[talltom]

> >       When I take off hard, after about 5-6 seconds, there is a
> > _severe_ misfiring that occurs. If I lift somewhat, it catches and
> > runs fine. Sometimes I can see the fuel pressure drop very briefly on
> > a gauge connected to the rail. I have replaced the stock pump with the
> > above Bosch pump (GFP215), and run heavy leads to it since the stock
> > wiring was too small. Also I have installed a #6 braided Teflon line
> > (.42" ID) from the pump and filter to the rail.
> >       I called Kinsler fuel injection for advice. They said my pump
> > should be plenty big enough, but that the in-tank transfer pump (rated
> > at something like 2 liter/min, which is marginal for 400 hp) might be
> > causing a restriction if I was trying to pull more fuel, and to remove
> > it. So I did, with basically no improvement.
> >       The tank has a 1.5 psi pressure relief valve to the outside air
> > (which also can allow air back in to the tank). It is working
> > properly.
> >       What's interesting is that the volume of fuel contained in the
> > new fuel line is just about the amount that would be moved in 6
> > seconds or so. This is why I suspect the problem is the pump itself,
> > or cavitating at the inlet.
> >       Any ideas gratefully received - before I start tearing it (and my
> > hair) apart...
> > Thanks!
> > -Charles
> > cmorris at ix.netcom.com

Duh, sounds like time to move the fuel pickup tube to wherever the fuel
goes in the tank during hard acceleration. Sounds to me like it may be
running
hard enough that the fuel is getting left behind! Most racing fuel tanks
have
provisions for this and or several pickups.
   I had this problem on my 54 cornbinder, it's so fast it ran away from
the 
fuel too!:-) I don't have the 745i here at the moment to look at the
tank
and see if that's the likely with it, but being stock(with o2 sensor) it
doesn't 
have that problem, yet!:-)