79SC - Replacing Both Major Engine Fuel Lines

[RarlyL8]

The main fuel line that extends from the tunnel to the fuel accumulator on my '79SC sprung a leak at the crimped fitting on the tunnel side. Thought I would snap a few pics during the repair so those who have not yet done this can see what is involved.
These are no fun to replace so I replaced both the inlet and the return lines while I was in there.
The location of the fittings on the tunnel side is not so good. A bunch of stuff comes through the tunnel at this point, and also the 915 trans mount is right in the way. So first thing is get the car up in the air, remove the sway bar mounts, lower the sway bar, jack and secure stand the trans, then remove the tranny mount.



I then loosened the fuel lines in the engine bay. Inlet goes to the accumulator, return comes from the fuel distributor. HVAC hoses need to be moved out of the way for access.





Moved down below and loosened both lines at tunnel. The fitting on the line that goes into the tunnel is not your typical hex fitting, it is square on 2 sides. A 13mm wrench fit the square. Hose fittings are 17mm. Have a pan handy to drain the fuel from the lines. Most of your cars are much cleaner than this one, made for a messy job.



Now if you follow the lines you see they go through these metal straps that are integrated into the body. It's not as bad as it looks to R&R but man is it messy with crap falling in your face! This shot is above the driver's side heat exchanger at the heater duct. The lines go through the firewall space which is filled with (deteriorated) insulation.



From up top I pulled one line at a time, going back and forth under the car so nothing was in a bind or being damaged. This would be MUCH easier with a helper.



Tape up the ends of the new lines so no gunk gets in during installation. Smear petroleum jelly on the tape so the fitting will slide easier through the metal straps.
Shout out to Len Cummings for making these lines for me, thank you!



I removed the left side heat exchanger and heater duct to get better access to that hidden metal strap. The charcoal canister vent line runs through this as well and snapped off in my hands like a brittle twig. Watch that so you don't have to repair it.



Connected the new hoses down below (blue letter is feed, white letter is return) then connected the return line ONLY up top.



Placed the J fitting for the accumulator in a glass coke style bottle and taped it to the neck so it wouldn't pop out. Turn the key to the first detent where the fuel pump runs and observed for leaks while priming the system. CAUTION - fuel flow from the unregulated pump will fill up a coke bottle in a few seconds. All good so connect the J fitting to the accumulator and run the pump one more time to check for leaks and purge air from the lines.



Now you have to put everything back. Install the trans mount, HVAC hose, heater hose, heat exchanger (if removed) then sway bar. This was pretty much an all day job. Small potatoes compared to some of the full restorations some of you have done but for the DIY guy with an old SC you WILL need to do this at some point. Hope these pictures help.

[betterair]

Brian,
thanks for documenting this procedure. ,
Yes were living on borrowed time regarding the main fuel lines.

[Bill Douglas]

Thanks Mr. Bodart. That was interesting.

[SkiVT]

Did you drain the fuel tank first? This one is on my project short list so thanks for documenting your steps/process.

[RarlyL8]

Appreciate the thought but no need to cover our addresses, both are businesses where customers ship items.

Did not drain the tank.
I made up a couple of plugs for the tunnel lines which were not needed. The car had set up for a time after it sprung a leak as I was too busy to get to it. When I unscrewed the tunnel lines not much fuel fell into the catch pan. I figured the check valve in the pump would prevent the tank from emptying on me but I didn't know about the return line. Return line had very little fuel in it. If the car doesn't sit for a time like mine did there will be residual pressure in the system and the lines will not have had time to drain down so you might want to make up some plugs. Mine were simple short sections of rubber fuel line with a bolt blocking one end that fit snuggly on the tunnel line fitting (which is the same fitting as on the FD side of the return line). You're going to get some fuel on you when pulling the old lines and pulling the plugs to install the new lines, no avoiding that. The floor under my car was a real mess when finished, used lots of cardboard.

[et cetera]

Bookmarked. How much does a set of these lines run?

[jimtweet]

I have to do this on a 83 soon. Not looking forward to it

[jjeffries]

Jim it's not difficult. Obviously easier when drivetrain is out. Len provides a female/female coupler so you attach the front of the new line to the back of the old one; pull the old line out up near the steering rack. That area is where things are the tightest. Pull the coupler, install it on the baxk of the other old line, pull and repeat. Helps to have a helper. Len makes nice stuff. John.

[RarlyL8]

It's not difficult just time consuming due to lack of access.
Lines were a little over two hundred for the set.

[Ian Comerford]

I understand you can still buy all of the lines from Porsche but are they ethanol resistant now?

[jjeffries]

Ian, I don't know the answer to that, but what's cool about Len's lines vs factory is that he makes them each with an extra threaded connection at the front of the tunnel, so in the future you can replace both front and rear rubber sections without touching the polyamid tunnel pipes, which seem to last indefinitely. And he uses ethanol-rated rubber. Best, John

[RarlyL8]

I looked up the Porsche part numbers and purchased the set of OEM lines. They sent me the wrong lines so I sent them back for exchange. They sent me a different set, still the wrong lines even though I spelled out that they were for a '78/9 SC. The main line was 2 piece which might have worked but that's not OEM. I'm not sure what's up with the part numbers but the later SC's had different lines. I sent them all back. Sent Len a picture of the PET, description of what they looked like and what fittings they had and he made the correct lines for the car. Feel free to use my pictures when purchasing these lines if you have a '78/9 SC so you get the right ones.

[mattypV50]

Question on this for you guys.

I have an 83SC...not sure if the lines have ever been replaced. Should I just be proactive and do this or wait? I wouldn't be able to do it myself so would need to get my indy shop to do it.

[shoooo32]

I ordered the lines for my '78 SC from our host and they were correct. If/when I do tunnel lines, I'll get them from Len though. His extra connector makes a lot of sense.

mattypv50- If your lines are original (and they most likely are) they should be replaced. More than a few 911s have burned to the ground due to neglected fuel lines. I thought mine didn't look too bad until I started removing them. They were pretty rotten. If you have any reason to drop the engine (reseal, head studs, clutch, etc) that's a great time to do it and your mechanic should be able to do it fairly quickly. With the motor out, I think it took me an hour and most of that time was spent cleaning the tub after the old lines were out.