Reroute Tunnel Fuel Lines Outside Car?

EWPurdy · 06-02-2005, 04:36 AM

I'm in the midst of doing some fuel system re-plumbing and I am contemplating running a new set of lines on the belly of the car vice through the tunnel. Is there any reason not to do this? Aside from being exposed to the elements, they will be much easier to inspect/repair out there and the idea of having fuel flowing outside the car is more appealing to me.

Thoughts? Experiences?

Porsche_monkey · 06-02-2005, 05:02 AM

I did it. Steel tube 8AN supply 6AN return. JIC flares. No leaks, no regrets.

EWPurdy · 06-02-2005, 05:25 AM

PBH,
Thanks. I saw your posts on the subject. Any reason not to use AN tube nuts/flares? The rest of my plumbing is already AN stuff

Porsche_monkey · 06-02-2005, 05:54 AM

No reason I can think of.

Jerome Ryals · 06-02-2005, 05:57 AM

I am currently parting out a 66 911 that a previous owner did this to. I was wondering why a piece of 1/2" square tubing had been welded to the bottom of the tunnel (under the car) it was a support or protector for the fuel line that ran through it. Of course it also had all the calipers installed upside down, the ones that should have been on the left were on the right and vice versa.

Porsche_monkey · 06-02-2005, 06:01 AM

The square tube idea is not entirely stupid. You could bottom your car out and crush your fuel lines. (I wouldn't ever drive like that, but you might.

)

David · David's Garage

Since the lines lasted 25 years, wouldn't new lines be safe for another 25 years? Running new fuel lines through the tunnel is not that difficult, I've done it a couple of times.

Porsche_monkey · 06-02-2005, 06:07 AM

I couldn't be bothered to locate and buy the lines locally. The tubing used is not common, and rubber tube won't fit.

EWPurdy · 06-02-2005, 06:24 AM

Replacing the lines through the tunnel is certainly an option. It just seems that it might be unecessary to go through all that and perhaps a bit safer to have fuel traveling outside the passenger compartment.

Porsche_monkey · 06-02-2005, 06:28 AM

Ive never heard of a serious fuel leak in the tunnel, but knowing the line runs there, every time I smelled fuel I would wonder.....hmmm is today the day?

73911guy · 06-02-2005, 07:33 AM

Lots of people find the fuel lines in the tunnel when drilling holes for aftermarket seat brackets. Especially humorous when you have a full fuel tank. Why everybody seems to find the fuel line when drilling instead of the battery cable to the starter seems to be that everyone starts with the driver's seat and the battery cable is on the passenger side.

Others of us have corrosion at the ends of the tubes outside the tunnel and need to replace them.

I'm still up in the air about trying to run a new line through the tunnel or under the car but need to decide soon!

Jim

cbeers · 06-02-2005, 07:55 AM

Still others have been welding inside the car and......hey..........what's that smoke from?

Is that.....................FIRE?

RUN!!!!

-Chris

304065 · 06-02-2005, 08:29 AM

Eric,

Inside the tunnel there is a sub-tunnel, the lines run through that.

They are protected from the elements and road hazards, and are in a pretty good position from a crash standpoint. I would NOT route them outside the car, the likelihood of them getting screwed up is too high (BUT I drive off-track a lot and my car is LOW).

In my opinion, it's pretty unlikely for a line to fail in the middle- it's far more likely for it to fail at a connection. When I ran SS AN-6 for my race car fuel cell, I ran single pieces all the way from the cell up front to the filter console in the back. It was time-consuming, but I have a great deal of confidence that it won't leak, and I have only two connectors to check. Just make sure you don't accidentally route the lines where they will chafe on the clutch or throttle cables, or, heaven forbid, against the main battery cable.

Now, I also commit another taboo, I have oil lines running through the inside of my car. This introduces some heat, but also protects the lines, and they are inside fiberglass firebraid (just like on your Hornet) so I'm not concerned about getting sprayed with hot oil in the event of a puncture.

EWPurdy · 06-02-2005, 09:12 AM

John,
How difficult was it to fish those -6 lines through? (Man hours expended?) Could you attach a -6 line to the old in the rear of the car and then pull the old line out from the front bringing the new one into place?

Porsche_monkey · 06-02-2005, 09:14 AM

I believe the existing holes are undersized for the equivalent (ID) rubber hose sizes, and the front hole is difficult to modify with the tank in place...

304065 · 06-02-2005, 09:19 AM

Eric,

The lines on an SC are steel, and they run through rubber grommets at the front and rear of the tunnel. If yours aren't seriously bent, grommets in good shape, etc., I would leave them in place, and just replace the hoses on the ends. Now, if they are damaged, seriously rusted, or otherwise unserviceable, then it's replacement time.

You can't use the old steel line to fish anything through, because it's rigid, and has a couple of bends at the ends. I removed mine by actually cutting it up piece by piece and pulling it out of the tunnel. I then installed a large PVC coupling at the rear of the tunnel as a bushing for the lines, but that was a race car application. In any event, there's no way the -6AN could just be pulled through, as its OD is about 2X the OD of the steel line.

In terms of total time, I would say that planning, fabrication, installation and pressure testing of the -6AN lines took about 20 man-hours. If I had it to do over again I would NOT use braided stainless, I would use Aeroquip braided kevlar, it's much lighter and won't abrade adjacent surfaces like the stainless will.

Now, other folks here have gotten a roll of steel fuel tubing from Jegs and some rubber grommets from Porsche, and used that to great success. If you are technical, you could put a nice flare fitting on the end of the tubing.

emcon5 · emcon5's Garage

Quote:

Originally posted by PBH
The square tube idea is not entirely stupid. You could bottom your car out and crush your fuel lines. (I wouldn't ever drive like that, but you might. )

I would go farther, and say the square tubing it a pretty good idea. If you are determined to run them under the car, that seems like a good way to keep them safe.

Tom

Porsche_monkey · 06-02-2005, 09:29 AM

'Not entirely stupid' is as close as I come to a compliment.

David · David's Garage

I've never seen or heard of the line through an SC being steel. It is a flexible hard plastic line with rubber lines on the ends. There is a steel fitting that attaches the plastic to the rubber. You can change them with the engine in place.

I've also never seen a separate tunnel inside the tunnel that the line runs through.

EWPurdy · 06-02-2005, 12:58 PM

Anyone know what size the stock metric fittings are on the lines in the tunnel? I guess I could leave the lines intact if they're OK and use some metric/AN adapters to plumb -6 lines to the pump/tank/fuel filter.