dcd215

Porsche 996 conversion -standard Porsche metric equivalent to 5/16 supply and return lines ,LS! intake manifold -new Napa gold 3737 filter/regulator. Return lines do not appear to be blocked or kinked I can easily blow thru to tank .However ,I put a gauge on the return line and it's reading 10 psi which I don't know if that is good or bad .Porsche chokes down the pressure to about 50 psi so the line sizes should work although they use a vacuum assisted regulator .

I would like to get the pressure in spec and would appreciate any and all comments/ideas .

Old Geezer

iTrader: (3)

1. Gauge accurate?
2. Run the return off the reg/filter to a jug, check psi at the rail.

stevieturbo

You have a feed and return with what looks like some sort of internal filter ?

Full details of the setup would help.

What pump, tank etc etc

dcd215

Chuck -gauge is pretty accurate .I will try the jug routine -pretty sure it will drop to 58 psi because when I turn the engine off it drops to 58 psi and holds . .The gauge is on the fuel rail .

Stevieturbo -It's a standard Porsche tank and pump-I do not have specs on the fuel pump. It is plumbed with the corvette filter/regulator in line with pressure readings at the fuel rail .Metric equivalent line 5/16 in and out .My initial reaction was the return line is too small but Porsche lowers it to 50 psi with that pump and those lines .I don't think there is a return line blockage but a key question is : is 10 psi on the return line ok or indicating a problem ?

Old Geezer

iTrader: (3)

What Stevie asked^^^^
A replacement pump, w/ higher flow, could be over running the line size[s].

Fierofly

iTrader: (1)

What year 996? My 2003 has no return line and a in tank regulator that I changed to get 68psi, I also replaced pump.

truckdoug

iTrader: (25)

the corvette regulator strikes again!

dcd215

It's a 1999 with the old style return line .I think it's the original pump -it looked untouched when I took it out to check for a blockage .

stevieturbo

So OEM Porsche tank, pump, fuel lines...

Where does the regulator normally reside on the Porsche ? And filter ? Presumably the reg must be near the engine as you say there are supply and return lines ?

IMO retain all these, and place an aftermarket FPR instead of the Porsche one then adjust pressure to suit.


Whether you are seeing resistance on the return to the tank...could be a red herring. There may be something in the tank, there may be a syphon pump on the end of that line, or it could be restricted for other reasons. A lot will depend on the actual tank design.

I can see little reason though to deviate from the Porsche fuel system in general, other than the regulator itself. Although if you were re-tuning the ecu or using an aftermarket ecu, you could run whatever pressure you wanted really, there would be no necessity for 58psi.

dcd215

Stevieturbo-Thanks for the input .The Porsche regulator is gone - it was integrated in the Porsche Engine fuel rail .The Porsche fuel filter is still there -it's about midpoint between the tank and engine .I did the corvette filter/regulator because it was easy , economical and read a lot of posts about how well it worked .There is no way I would change the Porsche lines -that would be a real project of marginal benefit .Think I will just add a regulator .

stevieturbo

Not add a regulator....install one regulator correctly.

dcd215

ok-I was thinking in line on supply to the rails after the corvette filter/regulator .Is this a bad idea ?

stevieturbo

There should be ONE regulator in the system.

dcd215

good point

dcd215

The regulator did the trick -steady 58 psi .

stevieturbo

Good stuff