More ? on Fuel Lines

[TimW]

On a stock ’73 FI 2.0L...

Can anyone comment on the pro’s and con’s of eliminating the plastic fuel lines that feed through the ‘deck’ by the battery in favor of running one continuous piece of hose from the FI fuel pump to the injectors and the Fuel Pressure Regulator to the FI fuel pump-T.

The benefit of eliminating 4 fuel line connections seems appealing.

[Rich Hilgersom]

Con,
Correct me if im wrong anyone, but I read in a few places that to qualify for many club events your are very limited in the length of flex lines you can have. Even braided lines that were sealed to the tubing so they dont cause that sawing action were not exempt.

I still have not got around to putting in my aluminum tubes. I found a tool from earl's that puts a bead on the end of the tube so you dont need to use those odd flare tools. So I will end up with mostly solid lines and hose clamps with a bead. It does not get much simpler that that and I trust it much more that compression flares.


-Rich

[roadtrp204]

pro: less effort and not as time consuming to install (the easy way out)

con: rubber line rated for fuel injection is rather expensive

con: rubber line dry rots, splits and spays gas onto hot engine causing 914 meltdown

The majority of air-cooled engine fires are from fuel line leaks. Rubber lines should be as short of a length as possible and used between and stationary and movable part.

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Chris
75 914 2.0L

[Stuart Lehr]

Are you saying that rubber fuel line anyone can get at O'Reilly's won't withstand 30psi?

[Dave at Pelican Parts]

Maybe it can, maybe it can't. You wanna take a chance on "maybe"??

Another "con" is that you will need to come up with a way to protect the rubber hose from abrasion by the edge of the hole in the engine shelf. The stock rubber gromet is made to fit around the plastic fuel line, and will not fit the rubber lines. Other measures would seem, to me, to be temporary. I would prefer a more permanent solution. A "bulkhead fitting" would work, but you'd still have those two hose/solid joints.

--DD

[TimW]

A couple comments on the above:

- Dry Rot seems the lesser of two evils considering my plastic lines crumbled and cracked in my hands because they were so brittle (one reason I wanted to eliminate them). They were probably original. Yikes! The rubber lines on the other hand were just cracked at the clamps. In any event, everything is getting replaced.

- I saw two issues with the grommet too. 1) The hole’s are oval to accommodate a plastic tube going through on an angle. Typical grommets being round won’t fill the hole and may allow excess movement. 2) Rubber fuel line is much thicker (12mmOD vs. 7mmOD for plastic). That would mean unless I drill the holes bigger to accommodate a large grommet, the grommet would have a fairly thin wall. Perhaps negating the benefit of eliminating 4 clamps.

- The pressure issue notwithstanding, O’Reilly’s probably doesn’t sell metric size fuel hose, only English 1/4 size which is 6.4mm and not quite the right size.

- As for the price, well, you can get upper and lower ‘kits’ for $90 at a place down south, or you can get the fuel line here at PP for about $35. So replacing everything won’t cost a bundle of money. Even if it was all high-pressure fuel hose.

No one really commented on what prompted this discussion, the benefit of eliminating those 4 connections? Does that mean it doesn’t really make a difference? If that’s the case then I might as well just stick with the original setup.

Tim

[Va914]

I am replacing the fuel lines and the brake lines all at ones. I have the tank out now, pulled it this past weekend.
I think I am going to use ridged brake lines and fittings for the fuel lines(PP Tech artical)..I don't have a bender so the fittings will make the 90's cleaner. I also was thinking about running the ridged in a larger rubber hose for protection (tunnel only), good or bad idea?

This past weekend, I noticed a small fuel leak in rubber hose, went to cut the piece off and CRACK! The hard plastic broke and Fuel when everywhere....Good thing I had 3 pairs of vise-grips close by, hu?

The plastic brake lines, should I change them to ridged?

What is the best way to paint the tank? I was thinking about using that bed liner paint for the tank and tank area. That stuff is real strong.

Thnaks

[bowlsby]

I have been using thick walled aluminum tubing as plastic fuel line replacement for about 2 years, available at hardware stores. I think its also used for icemakers and the like, but its nice and stout, yet easy enough to bend into the required shape without a tubing bender. I goes through the oval holes and stock grommets previously mentioned...which I was able to get new through Pelican recently. I also eliminated the rubber fuel line stringing over the back of the engine, by running this same aluminum tubing at the rear firewall and attaching it with rubber sleeved clamps to the rearmost firewall, to clean up the engine bay a bit, and eliminate more rubber hose.

[TimW]

I like the idea of using aluminum tubing (or rigid brake line), and I’ve seen it mentioned multiple times; but since metric tubing isn’t likely available at the local hardware store, don’t you still have the 1/4"OD (I assume you use 1/4") to 7mmID size mismatch problems? Or isn’t that .6mm size difference a problem?

[roadtrp204]

In my first reply I was under the impression that the fuel line was to be replaced from tank back. My fuel pump is up front, so I am unaware of the location and fittings of the pump on a '73.

My plastic lines behind the firewall broke apart in my hands, and that scared the crap out of me. For replacement I went with the steel brake lines. My feed and return lines are the same size, which 5/16" brake line was so close in size it was not worth it to worry about the difference. (I heard the earlier models had a larger feed line that 3/8" will work for)

Installing it was pretty typical of working on a 914, bending and contorting into all sorts of odd positions and the occasional four letter words, but they went in just the same as the PP tech article explained.

For safety, all cuts were double flared (this is the standard for brake and fuel lines) and fittings to use those flares were installed (90,s and barbed ends).

In reply to a post above, standard fuel line is rated somewhere in the range of 30 to 50 max psi but with a low working psi, it has a single nylon weave between the inner and outer layers, and will not support those higher pressures over and extended period of time. Fuel injection hose has thicker linings with multiple nylon weaves. Its working pressure is in the range of standard fuel injection systems pressures. The people at my local chain parts store didn't know there was a difference, scary!

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Chris
75 914 2.0L

[bowlsby]

The aluminum tubing I used was available in the same sizes as the original plastic lines...seems to me I used the 3/8" ID size as it was nearly identical to the plastic lines ID in my 74 914. Mybe it was 5/16"...I just don't recall. Either way, I checked the fuel pressure with my gauge and the FP regulator

I would'nt think twice about putting the same alum tubing in the center tunnel, but I would cover it with heat shrink tubing to minimize abrasion and noise.

[DK914]

FWIW, on my '74 2.0 I just replaced the plastic lines that run from the fuel filter, through those oval grommets and to the fuel press. reg. and the LHS fuel rail. I used 5/16-in. rigid steel brake line from a FLAPS (hey, I'm getting the hang of these acronyms!), which is a perfect press-fit into the 7-mm i.d. hose. The rigid lines were double-flared (too big for the hose to slip over) so I sliced 'em off with a dremel tool, then filed and deburred the ends. I figure the plastic lines stayed on for all these years without flared ends, so I know I'll be okay.

You really only need to make one 120-degree bend in each line, where it angles down toward the engine near the rear firewall.I used one of those hand=held "spool" tubing benders, rolling it on top of an old 2x4 to prevent the tubing from popping out of the channel and kinking.

Final step was to secure the lines near the bends. O.E. plastic clips for this purpose were broken and nicely crystalized, so I bought some of those nylon cable clamps (sort of look like a "p" from the side) from an electronics store. Use a clamp "toe to toe" on each tube, then secure with a single sheet metal screw through both clamps.

Oh, and flush out the tubes after cutting/filing...injectors HATE metal chips.

[TimW]

As it turns out the OEM plastic lines are NLA, so trying to use them is a mute point.

BTW: FLAPS is your Favorite Local Auto Parts Store (I had to look that one up ).

[bowlsby]

I tried the steel brake line approach also and had NOTHING good to say about it. The steel tubing was (as steel is) very rigid and would not take bending well at all. As I recall it even split at the seam. I was only trying larger radius bends (~4" radius?)and could not get it to work. I seriously doubt if the tight bends (<1" radius)required where the fuel line exits the center tunnel at the firewall could be made with the steel tubing...maybe with special equipment or thin wall tubing? Brass angles fittings are another source of potential leaks and I wanted to eliminate that possibility.

Thats when I used the aluminum tubing...no regrets. Although I did read somewhere a passing allusion to a reaction between the gasoline and aluminum, the person had no references to back-up his concerns and I have not noticed any negative effects in the 2 years they have been installed. The aluminum, like the original plastic tubing, does not need flaring or and end treatment, just clamp the rubber hose and go. I wonder if there is a recommendation on a torque setting for the fuel hose clamps?

[Va914]

I am kind of up in the air on which method to use. Aluminum tubing and bend it or Brake lines with fittings.

It seems both will work just fine but some of the post have concern aboout the fittings and leaks...

Hummmmmmm?

Time to flip a coin, hu?

[KWales]

Doesn't have to be aluminum or brake lines. I went to a shop that specializes in truck lines and hydraulic repair. They have anything you want. Just describe the application and the pressures involved. They found some hydraulic line that bent fairly easy and a high pressure right angle connector. If I had to do it over again, I would add a foot to the length to the lines from the firewall to the engine.

I personally like steel better than aluminum. When stressed repeatedly, aluminum can propagate cracks. That's why they inspect airframes and drill each end of the cracks. Might never happen in this application, but I have seen weird cracks occur from resonance conditions over time.

Ken