Fuel Pump Blues, take TWO.

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Okay, So since I bought my 2001 S8, the CEL would flash on WOT, but then go away, then it flashed at speeds over 120mph, and was fine at "normal" highway speeds.... (Around here, it's common to drive 82/83mph for hours and hours and hours.)

Well, I ran a few gallons of toulene in there to see if that would clean out any gunk, and it sure did. BUT it also took some life out of the pump too it appears, as now it's not happy if I try and go WOT or drive faster than 70mph...

So, I bought the wrong pump, then got the right pump, and when I went to remove the long bolt... POP, it's just turning the captured nut down on the venturi/siphon cup assy....

So, I have a car that runs great around town. And even at 55mph. But want to faster than 70? No dice. Want to acclerate at WOT for the onramp? No dice. (But it's plenty fast the rest of the time, and actually goes just fine, just flashes the CEL lamp.)

Here is my dillema.

The new housing is 800.00 or more.
The used ones are about 350.00 to 375.00.

I can get a in-line 255lph walbro pump for less than half that. (About a third actually.)

The pump in the tank/housing and siphon system all work just fine.

It's just not moving enough volume/pressure to feed the engine's needs at higher RPM, and under sustained load from what I can tell.

The in line Walbro would "suck" on the feed line to the injectors, I figure I'd mount it just after the stock Fuel Filter, in a section of "hose" there where it can be spliced in with minimal fuss.

Hook it up to power with a relay wired up to the stock system so it's only on when the stock pump is on, and it SHOULD be able to keep up with this engine's needs no problem, and I'd hope, the lack of "resistance" now on the old/stock pump in the tank would be able to allow it to feed the new in line Walbro just fine for many years to come.

Any ideas on this?

Has anyone done anything like this, or even considered it?

In my Supra days, we used to put twin in-tank Walbro's, and a few people did external fuel pumps with custom pick-ups etc. (All of them feeding 650rwhp engines needing far more fuel than this 360crank hp rated V8 will ever need.)

I know the in line Walbro's don't like to suck on the tank much. (IE: You want them close to the tank as possible, and have a easy source of fuel, but I've seen them draw through existing fuel pumps/systems with pretty good results, and where the stock pump on this A8/S8 is such a over-engineered mess, I'd rather just use it as the feeder system for a high quality external pump if I have to build my own, or spend 500.00 or more to try and get what's in this car to work correctly.

Thanks in advance for your advice guys.