Longhood fuel line layouts

[PNW Targa]

Found a pinhole leak in a section of fuel hose in the engine bay of my 1971 911T the other day. Replacing fuel lines just moved to the top of my list. I'm not interested in adding "engine bay fire" to my list of life learning experiences.

My question for the group has to do with the variation in the location of the fuel pump and lines in early 911Ts. I was expecting to find supply and return lines running through the tunnel to a fuel pump located in the left rear wheel well, as per the shop manual schematic:



Instead, it looks like there is a single steel fuel line poking out of the tunnel at the rear of the car, with a short length (~ 3") of fuel hose connecting it to another steel line that wraps around the left side and pops up into the engine bay through the top of the wheel well on the left side. Up in the engine bay (pictured below), a short run of fuel hose (the one with the pinhole) runs to a Mahle filter, with another short run of fuel hose running from the filter to a steel line that supplies the two banks of Webers.



So why does the schematic in the shop manual show a supply and return line running to a fuel pump at the back of the vehicle, when it appears that the fuel pump is in front near the tank? Is the location of the fuel pump up front a factory placement, or a change made by a previous owner? Given the age of the fuel hoses, it's hard for me to imagine that a previous owner went through the trouble of moving the fuel pump up front and installing a steel line through the tunnel. This 911T originally came with Zeniths. The PO installed the Webers some time ago.

Originally I was gearing up to order new tunnel fuel lines from Len, but seeing a single steel line exiting the tunnel makes me think that I should retain that section and simply replace the underbody and engine bay rubber hoses. Seem reasonable? It certainly means much less work to upgrade the fuel lines.

I'll end this with one more question for the group. Are there any downsides to pushing fuel from the tank through a deadhead system for fuel delivery? I've read quite a few posts about the pros and cons of up front versus in back fuel pumps, with no clear argument for one over the other. I was considering upgrading with a PMO fuel regulator, but that's not an option with my current system. Should I just make sure the fuel pump up front is delivering 3.0-3.5 psi to the steel tunnel line, replace the rubber hose segments and leave it at that?

[Nditiz1]

Most likely the OG pump died and they put one up on the steering rack. I believe they were back in the engine bay up until 75.

When you say a single steel line, do you mean there is no longer a return line in your tunnel? If someone went through the trouble to run a full steel line then I would just reuse that and as you suggest replace the engine bay line. You should double check the steering rack pump to be sure no cracks exist there as well.

[ed mayo]

70 911 had front pump. So possible carried over to early 71.lf no tunnel return line, and no mount on torsion bar housing, then was always front pump. Return from pump went directly back to tank. Rear mount pump had steel return line in tunnel. MFI cars had return line from filter console to tunnel. Carb 71 return line went from pump to tunnel line.

[PNW Targa]

Thanks for the info on the pump location for 1970 MY. Sure looks like what I have. I'll look closely at the torsion bar housing. The last few digits of the VIN are 0142, so it's relatively early in the series. Maybe built in the second half of 1970 before winter break?

I'll get going on the fuel lines in back. Next step will be to pull the cover plate up front and have a look to confirm the location of the fuel pump and replace those lines as well.