fuel lines for 73 3.0 upgrade

[speedo]

What kind of problems have fellow pelicans encountered with running fuel lines to a 3.0 update? And do I want to mount the 3.0 fuel pump up front, or under the left rear seat I'm hearing mixed suggestions as to what kind of lines to run and where to run them. I have had poor success trying to stuff things through the "tunnel" as they ALWAYS seem to get stuck on tie-wraps, somebody has used to secure the other cables inside.

[304065]

CIS cars had the pump mounted on the front crossmember just aft of the outlets from the tank.

I used braided stainless aeroquip -6AN and ran two lines through the tunnel after removing the steel lines. For a straight stock car I would stick with the braided factory stuff.

Installing the lines was one of the most difficult projects I have ever done, both due to the difficulty of removing the old steel lines, running the new ones through the sub-tunnel on the port side of the main tunnel, opening up the hole at the rear and installing a pvc grommet there. The lines enter the tunnel through the old duct that was used by the Webasto heater. With the pump on the crossmember you would want to open up the hole where the old steel lines went, and install a rubber grommet there to protect the lines.

I would NOT run them through the cabin or outside the car. Too dangerous.

[speedo]

Are those braided stainless lines a stock part? My 74 has CIS but I think it has solid lines.If not a stock part, how does one determine the correct lengths? I was fearing the "TUNNELL SYNDRONE", and was hoping there was an easier way. Maybe I could watch "Honey I shrunk the kids" a couple of times and crawl in there myself to guide the tubing through. I had to replace the clutch cable housing a year ago and almost decided that it would be easier to run the cable over the car instead of through it.

[304065]

Nah, the braided stainless is as far from stock as you can get. This stuff is Aeroquip, used in aircraft and racing applications, available from a number of distributors. They also make a lightweight hose with a braided kevlar cover, $$$.

If you want the stock lines for the tunnel I know they are steel, come prebent, and the ones for a '73 may have been superceded. To run a hard line in there, I would get some steel tubing from Jeg's or Summit Racing, it comes in a coil but you can unroll it, straighten it and slip it through the tunnel.

[speedo]

I misunderstood..when you said "for a stock car, I would stick with the braided factory stuff", I took this to mean that the factory made braided lines. I think my 74 has hard lines through the tunnell, but I'm not sure about the 73. And my 73 had the fuel pump mounted to the rear under the left seat.If my existing lines in the tunnell are hard lines and are ok, can they be reused with a cis pump or are there pressure and diameter issues?

[304065]

Yeah, by braided factory I meant the cloth-covered hose, available from Pelican. This is perfectly fine for a stock application.

I would check the archives but I don't think the part number for the steel lines in the tunnel are different-- something like 7mm feed, 8mm return or vice versa.

The operating pressure of the MFI system is 1 bar, and the bypass in the factory pump is 2 bar. I think CIS runs higher than that but you would need to ask a CIS guru whether the feed is adqeuate.

[IROC]

Originally posted by john_cramer
CIS cars had the pump mounted on the front crossmember just aft of the outlets from the tank.

Not until at least mid-to-late '76. The earlier cars continued to have the pump mounted in the rear. Since the line from the tank to the pump is low pressure, you could do something simple (hose clamps) back to the pump and then use the higher-pressure stuff from there to the accumulator.

I *think* my car has a braided line from the tank to the pump (it's braided when it leaves the tank and is braided at the pump - haven't verified every bit of it in between).

Mike
'76 Euro 911

[speedo]

Why wouldn't the entire line need to be higher pressure as the pump is both sucking fuel from the tank at high vacuum and pushing it to the accumulator at high pressure. It would seem that the return fuel line to the tank could be lower pressure....also anybody familiar with the hard black plastic fuel line available which utilizes metal metric fittings which are forced into the ends of the tubing and will sustain high pressures without requiring any clamps?

[Porsche_monkey]

1) you need to be careful what you use in the tunnel, I think there are too many sources of abrasion for rubber or cloth cover rubber hoses, this is not a place you want to have fuel leaking into

2) the stiff OEM hose can not easily be replace with anything different (ie rubber), because the OD will be too large to fit throught the openings at each end of the tunnel

3) with the rear mounted pump you do not have high pressure in the tunnel

4) just a suggestion, but when I re-did my car I ran steel tubing on the bottom of my floor pan, not throught the tunnel

[speedo]

So was the tubing underneath your car? And if you didn't need the high pressure tubing for a rear mounted pump, why did you use the steel tubing? Or was your pump front mounted? And if you needed to replace the tubing in the tunnell, why not just enlarge the openings to accomodate the larger size ODs?

[Porsche_monkey]

Yes it was underneath, outside, on the bottom of the floorpan. It clamped up against the pan. I used steel because a) it was available b) it was free c) it is strong d) flared steel tube when properly tightened will never leak.

My pump is rear mounted, and I ran high pressure fuel line (rubber type) up to the engine, with a short steel section where it passes through the frame.

The holes where the tubing enters the tunnel are difficult to access so it is not a simple job to enlarge them. You also need room for a grommet around the hose, so the hole becomes extra large.

I also do not think you should run regular rubber fuel line through there. Braided hose would be okay, but I think that wil be a big job.

Lastly, good luck running a braided hose out the front of the tunnel, then re-directing it and connecting to the fuel tank.