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  #1  
Old 03-31-2004, 05:58 PM
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308 F.I. plastic lines to injectors - Weak design?

Greetings to all - I am in the process of replacing all of the various fuel, coolant, and vacuum neoprene hoses on my 308, many of which are original and are in dire need of renewal.

I have a question about the series of small diameter plastic tubes which lead from the fuel distributor to each of the various injectors. These bundled tubes on my car appear to be in good shape, in that they are still a bit flexible, and there are no obvious signs of problems with any of them. However, imagining a 'worst case scenario', if one of these small fuel lines were to fracture, the result could easily be the spraying of gasoline onto the hot header area, and somehow I think this could ruin my day if it were to occur.

In general terms, is there any history of these small diameter lines frequently fracturing or splitting? Have these OEM tubes shown themselves to be pretty much bulletproof, or are they a ticking time bomb?

Thanks for all of your opinions and thoughts - DM / Ohio
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Old 03-31-2004, 07:29 PM
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I have heard that replacements for these lines are unavailable.
I have checked at several places and it appears that they are unavailable.
In fact, I was told that the manuafacturer came into the stores and collected the remaining stock.
Some cars used this type of tubing for vacuum lines.
VW uses a braided stainless line for this purpose.
I would be interested in hearing about repacements.

Mark
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Old 03-31-2004, 09:48 PM
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I would also like to know if there is an alternative to plastic lines. Mine were so dry and brittle they actually cracked and broke apart. How about some type of braided line? Any ideas?
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Old 03-31-2004, 11:31 PM
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The old 911s use the cis system similar to the gtbi/si. I had bought the
replacement nylon tubing in the correct metric size to replace the fi
tubing on my 77 911s but haven't got around to it yet. The tubing
and installation collars were very inexpensive from www.mcmaster.com.
You could find more info on this by searching fellow fchatter Wayne
Dempsey's Pelican parts website for info about "cis tubing" or "fi tubing"
good luck!
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Old 03-31-2004, 11:48 PM
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The PelicanParts link you want is:
http://forums.pelicanparts.com/showt...=Fuel+AND+line

It reads:
Quote:
Originally Posted by Jim Simms
www.mcmaster.com

The line is black nylon 11, this is the same material as the old line. The temperature, pressure and chemical rating information may be found on the McMaster-Carr web site. You can order on-line with a credit card.

3mm ID x 5mm OD: stk number 50405K12@$0.26/ft by the ft.

4mm ID x 6mm OD; stk number 5040K13@$0.31/ft by the ft.
(this is the fuel distributor to injector size)

6mm ID x 8mm OD; stk number 5040K14@$0.43/ft by the ft.
(this is size from fuel filter to distributor if this line is plastic on your car)

Also consider Polyolefin Thin-wall Heat Shrink Tubing 3/8" Expanded ID, 48 " Length, Black; stk number 7856K161 @$1.93ea

I also ordered the following collars to make the installation tools; the OEM tools are now scarce:

Metric One-Piece Clamp-On Collar Black Oxide Finish, 5mm bore, 16 mm OD, 9mm Width; stk number 57445K22@$2.19ea

Metric One-Piece Clamp-On Collar Black Oxide Finish, 6mm bore, 18mm OD, 9mm Width; stk number 57445K23@$2.29ea

Metric One-Piece Clamp-On Collar Black oxide Finish, 8mm bore, 24 mm OD, 9mm Width; stk number 57445K24@$2.24ea

Old line is burned off fittings. Slit the collars at the narrow neck with a dremel abrasive disk or a fine hacksaw so each breaks into two pieces. Wrap a bit of fine sand paper (for enhanced friction) around fuel line then put collar around sandpaper and line and tighten set screw. Make sure only a small portion of the nylon line extends out of collar Mount collar with line into a vise; then hit fitting into line with a soft faced hammer to force fitting barbs into line. Buy extra line to practice with, you'll need it and its cheap. Use shrink tubing to add an additional scuff layer and heat insulation to injector fuel lines; remember to slide it over before installing the second fitting onto the line. Wait and shrink the tubing with a heat gun after you install the second fitting in case you make an error installing the second fitting. We made a set this way but are yet to pressure test them; need to get an old injector to weld an air fitting to in order to make the pressure test. Making these lines is a bit of work but can be done. I'll send you 15 ft of the 3 x 5 line if you send me an address; since I had to buy a 100 ft. I have lifetime supply. Cheers.
Jim


Last edited by Jim Sims on 10-25-2003 at 03:11 AM
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Old 11-13-2007, 07:44 PM
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Anyone done this yet? I have a bad fuel line between the fuel distributor and injector (the plastic part) and need to replace it. Is the above info the best way to go?

Thanks

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Old 11-13-2007, 07:57 PM
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This is the stuff for the Mondial/308 injectors (between the fuel distributor and injector hard lines) based on the measurements of my car:

3mm ID x 5mm OD: stk number 50405K12@$0.26/ft by the ft.

However that part number is discontinued. The new one is: 50405K24
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Old 11-13-2007, 08:46 PM
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DONT USE 6x3 line between distributors & injectors!!

I've been poking around the CIS threads on the 911 forum. The 911 guys have found that that McMaster 6mm OD x 3mm ID line isn't rigid enough, it damps the oscillation of the little needle in the injectors, resulting in miss-firing & running lean!!!

You need a 6mm x 2 mm line (2mm wall thickness) - See quote below.

D&S Sales has the correct line, along with banjo fittings, etc:

http://www.dssales.net/CIS.html

Here are some relevant links on the 911 forum, including tools & tips on inserting the barbs into the CIS tubing:

Pressing nylon fuel lines onto barb fittings
http://forums.pelicanparts.com/showthread.php?t=184617

CIS Fuel Lines http://forums.pelicanparts.com/showthread.php?t=338156

Alternate CIS fuel injector hose/tubing?
http://forums.pelicanparts.com/showt...hreadid=185323

CIS misfire
http://forums.pelicanparts.com/showt...hreadid=236328

Bottom line from the preceding thread:

Quote:
Originally Posted by Rondinone
Here's a question: How many of you with this problem have replaced your fuel lines between the distributor and the injectors using aftermarket tubing?

I replaced mine last year using a method on this board and tubing (exactly the same part #) from McMaster-Carr. The new tubing is NOT sufficiently stiff, and at light throttle opening creates a pulsation in the fuel injector. That is, the injectors should open and spray continuously, but mine would click on and off proportionally to the throttle opening (and inversely proportionally to the length of the injector line!). At low throttle opening (cruising) the car had a classic lean miss. At higher throttle the pulsations become continuous and the car ran well.

I fixed the problem by reinstalling some old lines of a 77.

The original Porsche tubing on my car was 6X2mm. McMaster only sells 6X1mm.
Sorry to bring up a P-word car, but you gotta give credit where it's due...
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Last edited by Verell; 11-13-2007 at 09:18 PM.
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Old 11-13-2007, 10:49 PM
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Hey Verell,
Thanks for the links. I gave it a read. The only thing that is confusing me is that the Mondial fuel line is on my car 5mm OD and 3 mm ID, so it has 1 mm wall thickness. This is the same as the McMaster. Are the Porsche guys using the same line size? 6x2 is a mm larger on OD and a mm smaller on ID. I can't imagine how you would get it installed on the hard line without destroying something. The dssales website talks about needing to use a speacial reamer to make the end large enough to get on the hard line, but there is no link to that tool. Sounds sketchy....

This all sounds logical, but why can't I just buy the CORRECT line...in the right rigidity to prevent pulsing? It must be available somewhere.

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Last edited by Birdman; 11-13-2007 at 11:01 PM.
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Old 11-13-2007, 10:51 PM
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In This thread they discuss Boxer fuel line and the proper size is listed as 6x2. I just checked my car again with a caliper. My car has 5x3 on the rear injectors and 6x3 on the front. So it looks like they replaced the rears at some point with the wrong thing. I think 6x3 is the right thing to find. It sounds like dssales is selling 6x2 and making people modify it to work.

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Last edited by Birdman; 11-13-2007 at 11:00 PM.
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Old 11-14-2007, 07:51 AM
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Back in the day (1970's) some fuel lines were plastic. My Lotus had all plastic fuel lines in fact. It is well known that modern fuel additives will make this plastic get brittle and crack over time. I have replaced all mine with modern stuff as well as changing the two plastic "T"s to brass. I don't know what Ferrari used in the 1980's but if it's the same kind of plastic I would be VERY worried about fuel leaks.

Ken
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Old 11-14-2007, 09:01 AM
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Just measured my Euro QV's injector lines, OD=6mm unfortunately there were no markings.

IF 6mm OD, 3mm ID are the correct dimensions, then Newman's 1/4"(6.35mm) OD, 0.0625"(1.58mm) wall thickness -->0.125"(3.175mm) ID tubing is close enough, & has a thicker wall.

The 50405K24 is Nylon 11, with a hardness of Shore D70. That's pretty hard(think plastic hard hat material) for a plastic, the harder the wall, the less it will pulse.

Note that nylon tubing comes in several types, each with a range of hardness. (eg: Nylon 6(96A-112A/46D-81D (Hard)
R 112), Nylon 11(57D | 70D ), & Nylon 12(50D | 63D )).


I just searched McMaster & they' don't have 1/4" OD x 0.062 wall nylon line. But I did find 5437K111: 6mm OD x 3mm ID (1.5mm wall) line, Nylon 12 , 50D hardness & flame retardant. Rated for 175psi.

MSC has a 65095481: 1/4" OD x 0.062 wall nylon line rated for 500psi, but they don't spec hardness tho.

I suspect the D&S Sales reamer is just a simple taper reamer, probably matches the barb's profile except maybe 1mm undersize. It's the sort of thing that BOSCH would do. Certainly wouldn't be hard to make a tapered reamer out of 1/4" steel rod, hour or so with a lathe & mill. Nylon's soft enough so wouldn't need any hardening.
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Last edited by Verell; 11-14-2007 at 09:11 AM.
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Old 11-14-2007, 10:50 AM
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Hey Verell,
Thanks for the help. I'm getting there. I just called Bel-metric right in MA and they have in stock the 5x3 stuff made by Cohline that is on the rear bank of my car. He is going to check the catalog to see if they make a 6x3. If so, we can order it, but he needs to order a big roll.

Group buy!?

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Old 11-14-2007, 12:36 PM
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Hello from Germany,

maybe you Bosch FI-owners are interested in contacting the classic car division, Bosch founded around three years ago.

http://www.automotive-tradition.de/en/start/index.htm

You can not only download several Bosch documents, spare parts lists, etc., but also send them your individual inquiries via e-Mail or a phone hotline.
They are very helpful and I'm sure they will answer your questions regarding the FI fuel lines thoroughly. Maybe there's a procedure for replacement of the old clear plastic lines with the more reliable steel braided lines, VW, for example, used on their GTIs.

I had a similar problem some time ago with the fuel injectors of a Bosch L-Jetronic and with the help of Bosch's Automotive Tradition department I quickly solved it.

Best Regards

Martin

Last edited by Martin308GTB; 11-14-2007 at 12:38 PM.
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Old 11-14-2007, 02:29 PM
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Quote:
Originally Posted by Martin308GTB View Post
Hello from Germany,

maybe you Bosch FI-owners are interested in contacting the classic car division, Bosch founded around three years ago.

http://www.automotive-tradition.de/en/start/index.htm

You can not only download several Bosch documents, spare parts lists, etc., but also send them your individual inquiries via e-Mail or a phone hotline.
They are very helpful and I'm sure they will answer your questions regarding the FI fuel lines thoroughly. Maybe there's a procedure for replacement of the old clear plastic lines with the more reliable steel braided lines, VW, for example, used on their GTIs.

I had a similar problem some time ago with the fuel injectors of a Bosch L-Jetronic and with the help of Bosch's Automotive Tradition department I quickly solved it.

Best Regards

Martin
I'm sure some of you are already on this, so rather than 50 guys contacting Bosch, I'll wait for your posted results........in the meantime,

Quote:
Originally Posted by Birdman View Post
Hey Verell,
Thanks for the help. I'm getting there. I just called Bel-metric right in MA and they have in stock the 5x3 stuff made by Cohline that is on the rear bank of my car. He is going to check the catalog to see if they make a 6x3. If so, we can order it, but he needs to order a big roll.

Group buy!?

Birdman
In the event that Bosch does not come thru w/replacement lines, count me in for some of that 5X3mm stuff (though my lines look in great condition but should stock up on it for the future). I'll get back to you w/a # after I do a take-off if this is the only route to take.
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Old 11-14-2007, 03:39 PM
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Please count me in if you do get that 5X3mm stuff. My 328 is now 19 years old ....

Thanks,
Rui
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Old 11-14-2007, 04:41 PM
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Guys,
The 5x3 is easily obtainable at a place near me. Unfortunately, Verell and I are pretty sure that while it clearly will get the job done, it is NOT the same spec as OEM, which I believe is 6x3. I am looking into finding the correct 6x3. Stand by.

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Old 11-14-2007, 04:48 PM
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I searched that Bosch website and they list nothing for this fuel line. They do list most of the other CIS parts though. Might be a source for people looking for warm up regulators, etc.

I have some tips from Brian Crall to follow up on. Dave Helms....you out there? Brian says you will know the part number and where to get this stuff.

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Old 11-14-2007, 06:38 PM
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Larry Fletcher says use Cohline polyamide line.

Just spoke with Larry Fletcher (CIS repair source) He said that the line to use is German polyamide(Nylon(tm)) line made by Cohline as Carmine mentioned in the other thread. Larry's pretty sure that the correct size is 5mm OD x 3 mm ID. That's definitely what he uses in his CIS test equipment, he read the dimension off of his roll of line while we were on the phone.

BTW: "Polyamide: Polymer formed by the reaction of a diamine and a diacid. Nylons are commercial polyamides"

Larry gave me a contact to call to double-check on. Will call tomorrow AM & post what I find.
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Old 11-14-2007, 07:15 PM
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keep up the great work guys.............. forza......... i'll stay tuned
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