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304065 304065 is offline
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Join Date: Dec 2001
Posts: 9,509
Hmm. OK, here's my last guess. The ATL is a top-loading cell. That means that the pump has to pull fuel from the bottom of the cell, up about a foot, around the back of the cell, through the fuel filter and then push it through the system. Based on my own experience, that's a pretty long way. Some guys mount the pump right on top of the cell for a very short run.

The sound you are hearing on startup is cavitation of the pump in air. It probably runs for a couple seconds, makes a pretty loud whir-whir-whir pulsing sound and then there's a pitch change as the fuel gets sucked through. I think that in the time that it's priming, the seal is overheating. The pump uses the fuel as a coolant and when it's sucking air, no cooling is happening.

The same thing happened to me when I was using a Mallory pump, which even had an air-bleed in it that was routed to the return line via a "T" fitting. It would run fine at idle and even high RPMs for a while, but on long sustained stretches, like through the esses at Watkins Glen, the fuel pressure would drop and the motor would lean out.

Good luck! I'm out of gas on this one (pun intended!)
'66 911 #304065 Irischgruen
Ex-'71 911 PCA C-Stock Club Racer #806 (Sold 5/15/13)
Ex-'88 Carrera (Sold 3/29/02)
Ex-'91 Carrera 2 Cabriolet (Sold 8/20/04)
Old 01-27-2004, 10:54 AM
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