On to my next project... Leaking Fuel Pump Flange?

[jplumlee]

ok so I got the drive shaft replaced and she's purring like a kitten. So i guess ill try to figure out where this gas leak is coming from.

I've read this thread :

http://www.renntech....ear-wheel-well/

and its exactly my issue. What i cant figure out is which part is actually leaking?

btw... this cavity was full of gas.

this is the drivers side access panel under the back seat

PTEC's reply with part #

"RFM is right on the money. The most common cause for this is a leaking drivers side fuel tank flange. Should be part # 955 620 841 00. Due to the design of the tank, both flanges must be removed( there is one on each side of the tank) so you'll also want two sealing rings ( 955 201 133 01) There is an updated pipe that porsche wants you to install on the drivers side flange as well, 955 620 911 001."

im a little confused what going on. what do they mean by "both flanges"?

As usual, a BIG thanks in advance!!!

Edited December 3, 2012 by jplumlee

[bigbuzuki]

Both flanges as in one under the left fuel pump access cover and the other under the right fuel pump access cover.

If you were to change the updated pipe they mention, you would have to access both left and right fuel pumps thereby requiring 2 new flanges and sealing rings.

BTW the left side has the fuel filter, the right side has the fuel pressure regulator. Could be a good idea to change the filter when accessing the left side.

Edited December 3, 2012 by bigbuzuki

[Zuffenhausen955]

The upper "dome" portion of the flange, is the part's Achilles Heel. High tank pressure(especially under high ambient temps) makes the top part of the dome split and crack. If you have no check engine lights but hear NO pressurized, "whoosh" sound when uncapping the tank to refuel.....expect to soon smell gas fumes, under the rear driver's wheel well. If left unchecked - the dome's condition worsens to the point where the flange will shoot raw fuel towards the bottom of the interior fuel tank port cap, dribbling fuel as you drive. 

 

You can cut the install time of the filter flange 45min, by simply replacing the top portion of the flange, leaving all the in-tank hoses intact. . 

[clarksongli]

The upper "dome" portion of the flange, is the part's Achilles Heel. High tank pressure(especially under high ambient temps) makes the top part of the dome split and crack. If you have no check engine lights but hear NO pressurized, "whoosh" sound when uncapping the tank to refuel.....expect to soon smell gas fumes, under the rear driver's wheel well. If left unchecked - the dome's condition worsens to the point where the flange will shoot raw fuel towards the bottom of the interior fuel tank port cap, dribbling fuel as you drive. 

 

You can cut the install time of the filter flange 45min, by simply replacing the top portion of the flange, leaving all the in-tank hoses intact. . 

So this isn't quite right.....gas tanks these days are held in slight vacuum, hence the evap solenoid.....since basically 96 when we swapped to OBD2.

 

What Zuffen is referring to is the pressure regulator (passenger side) and the FPR (Driver Side) are both on the "pressure" side of the pumps......roughly 45 psig.  If these become damaged or brittle, they will spray fuel.  Since our cars run a fuel return, the pumps are "dump" and will continue to run to maintain the pressure required.....which in turn will just spill gas out the top of the tank ports.

 

 

Honestly, when I replaced my pumps, all I did was clean the surfaces really well and reinstalled the gasket.  The gasket is a rubber compression gasket, so as long as there are no cracks and the surfaces are clean, there is no reason to replace the gasket.  We aren't talking about an o ring or crush gasket where you have a finite amount of compression on the sealing surface......you simply reinstall the locking ring, which allows you to find tune the compression on the gasket by tightening it further.  Careful, you CAN crack the plastic if you go too tight.

 

Just my 2 cents.