[urq] Fuel Pump surge - still having problems

[Ben Swann]

I'm beginning to like this idea as a solution - it would also tend to keep the filter
sock blown free of any restriction and apply additional positive pressure to the intake.

I'm not quite pictureing exactly what you are describing, but kind of like the idea of a
hard 1/2" Cu line going directly into the tank - coupled by a small Fernco(rubber pipe
joiner).  The return line could feed into the tee.  Another tee into the hard line could
use the return line to tank fitting to flow in the opposite direction - providing
additional fuel feed instead of acting as a return.

Doing this would be a lot better than performing any surgery on the otherwise perfectly
good tank.  Maybe need to feed a tiny surge tank to prevent any voids - is that what you
are suggesting.

I think there is a solution in the works - some Cu pipe, fittings, tees, Mapp torch - it
has to at least result in improved flow into the pump.

Now if I can just drive the car enough to clear out remaining 14 gal of fuel -
problematic with sloppy shifter that has also been driving me nuts - at least I found
the problem was a loose ball on the shift link.

Appreciate any input into this scheme.

Ben


-----Original Message-----
From: Ado Sigal [mailto:a.sigal at bluewin.ch] 
Sent: Thursday, April 17, 2008 1:50 PM
To: Ben Swann
Cc: urq at audifans.com
Subject: Re: [urq] Fuel Pump surge - still having problems

I believe that your problem is that under acceleration, the pump manages 
to draw the air from the fuel surface. Below 1/2 tank suggests this to 
be the case. A proper surge baffle of decent capacity, which Ur and most 
tanks with outside pumps are missing, would be a solution. (reason why 
in tank pumps don't have this problem, is because there is always decent 
surge baffle pool, and large pump intake close to the bottom). If you 
don't want to open the tank, other solution would be to return the fuel 
directly in front of the pump intake, instead of elsewhere in the tank. 
Simple longitudinal small capacity self bleeding cylinder (top line from 
the tank, bottom to the pump, and fuel return on the side) directly 
before the pump, should solve the cavitation and fuel starvation 
problem. In this scenario, the amount of fuel drawn from the tank would 
be only the amount of fuel used by the engine.

Regards,

Ado



Ben Swann wrote:

>Essentially what you say that I'm "flowing way too much fuel to return it to the pump
>unused" is how it is done usually.  If not I'd like to know.
>
>Still - I'd like to find out how to keep the cavitation from happening.  - 
>some point during running, the fuel starts to bubble and cavitation during running.  
>

I do notice it seems to happen more as the tank goes to below 1/2 - 
still a lot of fuel in the tank tho.

>Ben
>
>  
>