AN fittings for stainless fuel lines?

obnoxiousblue

I put German braided lines on my bus last year. Have had some leakage coming from the line to my BN4 for about two months now, so I bypassed it while I figure my next plan. Even had a convo on the issue with RandyInMaine at Litchfield this year.
I've been reading the fuel line threads for about 3 weeks trying to figure what is best. None of my other fuel lines feel wet, nor smell, or feel soft/weak.
Though a friend had once suggested we upgrade my bus to stainless lines with fittings as they would be virtually leakproof and maintenance free.
He's said it to me a few times, and I've always kinda pushed it off, but I'm curious what the Bay forum thinks of such an idea?
Is it worth the effort? Has anyone seen it done? Should I just go Gates?
_________________
Mike
1964 Beetle
2001 Eurovan Camper

blackivory69 · Posted: Sun Jul 27, 2014 11:12 pm Post subject:

I just did that. I have a type 1. Stainless steel line from fuel filter under the tank, then it went trough the front tin, under the left intake manifold, 90* by the heat riser, and it ended by the pump with a 2" rubber line. Sound cool right. Well, not according to my engine builder. Because after I drove the bus for 15-20 min and turned off the engine, it will not start again for at least 15-20 min. So I called my builder and told him my issue. And he asked right away to check my hard line. Why? I told him I have like 2-3 ft of stainless steel. Check for what? VAPOR LOCK. And I knew right away that it's possible because the line was hot (it was in the 90s here). So I yanked it out and bought Gates FI hose. Now, I only drove the bus one time around the block but it seems the problem was gone, and I think that was really the issue. So if you're gonna do the hard line, make sure to route it as far as possible to any heat source. Goodluck. Cool

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chazz79 · Posted: Mon Jul 28, 2014 3:43 am Post subject:

You might have been ok by just slitting rubber hose and sliding it over the stainless to act as an insulator.

I'll take pictures of mine after work but I'm using nylon. This covers all but the las 2" next to the tank that is used as a coupler.
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aeromech · Posted: Mon Jul 28, 2014 7:35 am Post subject:

This is some pretty good stuff. Shop around. I think you can get it cheap from Amazon if I recall

http://www.gates.com/products/automotive/passenger...n-hose-mpi
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chazz79 · Posted: Mon Jul 28, 2014 6:47 pm Post subject:

Here's what I switched to. It's a work in progress before I hit the road with this and I'm weeding down the amount of hose used.

Image may have been reduced in size. Click image to view fullscreen.

There are a multitude of adaptors available and this stuff is made for e-85 at way higher pressures than our busses can handle. Both of those points make it better than any rubber based product.

The very worst I can do is adapt back to steel with a 2" rubber hose used as a coupler at the fuel tank. Until there's a way to eliminate questionable quality hose, the best solution would be to limit its use in the fuel system.
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One day as a lion, or a lifetime as lamb

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Mr. Unpopular · Posted: Tue Jul 29, 2014 8:19 am Post subject:

Chazz, can you tell us what "this stuff" is? You have a shaky picture of a rubber line in one picture, a hard line in another picture, and no real details.
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chazz79 · Posted: Wed Jul 30, 2014 6:41 pm Post subject:

Ok, first picture to the left is a hard plastic nylon line. It looks like a battery cable. On the right side of the pump is rubber line that I will be switching over to more nylon.

That same upper pic shows the fittings required to connect to the fuel pump. These are tooless snap fittings. You press the colored part of the coupler and it comes off the pump. The line then stays attached to the engine for drop outs. The nylon is very flexible, crush resistant and chaffe proof. The second picture shows the tools needed to work with this. Really small crush clamp pliers and a heat gun are about it. The plastic fitting is just a close up of what you'll be putting into the end of the nylon line. That steel line is what I'll be clamping onto the very end of my nylon to join to my fuel tank.

Ultimately I will be down to 2-2" couplers used to attach my nylon to the fuel tank nipples. Everything past that will be this nylon/nitrile flex fuel compatible line set that oems have been using since the late 90's.

I'm finishing up my swap I'll be completing the fuel system this weekend so better pics will be around sooner or later.
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Mr. Unpopular · Posted: Thu Jul 31, 2014 5:33 am Post subject:

I'm not the best person to keep up routine maintenance, so 2" of rubber line might as well be 2'. I want to eliminate all potential for fuel leaks in my setup. I don't mind spending the money for stainless braid, but if the new gates hose is proven long term, I'd rather avoid the cost and hassle of stainless braided.
_________________
"In any racing engine, the nearer you are to it disintegrating, the better it's performance will be"
-Keith Duckworth, creator of the Ford/Cosworth DFV

Skyline · Posted: Thu Jul 31, 2014 5:43 pm Post subject:

Stainless braid over rubber is a five year replacement item. Read up on some of the hot rod site. All fuel systems will require maintaining.

old DKP driver · Posted: Thu Jul 31, 2014 6:20 pm Post subject: fuel line replacement

I agree with Skyline but I am going a bit farther and will use (PTFE)
Teflon ultra flex which is covered with Kevlar it's being used more and more
since ethanol will not degrade it. to me it's a couple steps above the
submersible fuel hose used on In the tank fuel pumps now.

I too am becoming paranoid about fires since I hear at least once a week of
a car on fire somewhere in the bay area. All these fires are not on just old
vehicles either.

It's also a fact that even in F.I. systems with high volume recirculation that
the return line to tank from the engine will aerate the hot fuel causing the hose to break down from the inside.

We can't even be sure how much ethanol is really being blending here and in
other states. Evil or Very Mad

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Mr. Unpopular · Posted: Sat Aug 02, 2014 10:48 am Post subject:

Yeah I plan on Teflon with stainless or Kevlar wrap.
_________________
"In any racing engine, the nearer you are to it disintegrating, the better it's performance will be"
-Keith Duckworth, creator of the Ford/Cosworth DFV

surfbum · Posted: Sat Aug 02, 2014 11:58 am Post subject:

Hi.

I use aluminium tubing for all but the AN6 hose from the regulator to the Yconnector for the carbs. Cost a little but so does a engine fire...

Here are some pics...

Cheers
//Daniel Thelin - Sweden

Want to see my bus? The link is below...
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raygreenwood · Posted: Sat Aug 02, 2014 12:28 pm Post subject:

Actually the teflon kevlar is not really being used much. Maybe a few people in aftermarket yes......but it has 0 advantage over modern nylon alloy lines....which virtually all passenger cars have gone to since about 2000. And for good reason.

1. This is not crappy old school nylon like you found on CIS injection in BMW and Saab that gets brittle with age. These are nylon 12 alloys with special mfg processes
There are several primary formulas used by various auto mfrs with subtley different characteristics.....all of which are perfect for alcohol blend fuels up to e85. Some have better abrasion characteristics, some have slightly better heat characteristics.. etc.

2. The pressure rating far exceeds any rubber based line.

3. The nylon lines are far cheaper than steel or rubber In any category.

I decided about 2 years ago to go all nylon in my current build. However there are some rules to using nylon lines....and where to use them and not to use them. You can learn these rules strictly through observation. Go look under the hoods and chassis of about 10 new cars....a range of brands....any brands. What you will find:

1. When connecting to high movement parts .......engine to fuel loop, chassis line to external fuel pump....or in general fom nylon main to anything not rigidly bolted down....manufacturers use short length high pressure rubber hose with swaged ferrule ends on barbs or clamps on barbs.

2. Through areas of high vibration and very detailed conforming curves like following the fire wall behind engine....they use cnc machine bent galvanized or stainless steel with barbs or clamps. AN fittings are cool but 100% unnecessary for anything less than direct injection and diesel pressures or racing classes that require them.

3. Semi- rigid nylon everywhere else for long runs using either specialty push-lok with o-rings for high frequency replacement items like fuel filter....and soft edge barbs for joining....some clamped...some specialty crimped or force fit connectors.

Also....stainless steel or steel lines in general do NOT cause vapor lock. Poor routing of any material type of any fuel lines causes vapor lock. Metal lines do conduct heat faster...but they also shed heat faster. The point is if you get vapor lock with ANY type of line....its routed poorly. If its going through a hot area...sooner or later any line material will get hot enough to cause vapor lock. It does not have to be 180-200F. Remember tha5 fuel evaporates xown to about -40F. About 125-140F at low pressure in a carbed engine will causes fuel evaporation bubbles. Look at your routing and contact points long before you worry about line material.

Also...DO NOT use LDPE or HDPE anywhere in your fuel system. There is no polyethylene alloy on this planet that has a temp range anywhere near what you need to have in a vehicle for fuel use. When they get north of about 165F they get brittle and lose a good bit of their chemical resistance. Polyethylene can handle the chemistry of fuel....but not combined with temperature....either extreme hot or cold.

In before you suggest it....as I know someone will....NO.....plastic fuel filter housings are NOT made of polyethylene. They are made of polypropylene. Different animal. Some are even nylon alloys....more all the time.

A great place to get nylon fuel tubing by the roll....many kinds....is Summitt racing and several other muscle car hot rod sites. I think Jegs sells some as well.

Do your research on joining tubing. Lots of info and tools out there including a tool that is basically a modified caulking gun that holds the fitting in one end and the line jn the other and with ratchet force...joins them on a barb. Double ended barb fittings ....brass or stainless with mild heat and a plier tool is awesome and leak proof to about 300 psi.

Nylon fuel tube is the best long term answer to fuel proof tubing I have seen in eons.....and its very cheap....about half of what Gates barricade runs or less. Ray

EDIT: I forgot to add that the best fuel line I found for my 412's gas furnace...or any gas furnace for that matter is either metric or 3/16" steel line connected at the metering pump with a rubber fuel line nipple and a plain old brass or steel compression union. I had to polish the end of the ljne both on tbe heater inlet and the fuel line to get a percect fit in the ferrule. But it has been leak free for over 20 years. No, special AN fittings neexed and you xan take it loose anytime.. it runs virtually 0 psi.

old DKP driver · Posted: Sat Aug 02, 2014 5:44 pm Post subject: Nylon lines

Interesting Ray

Do you have any pic's to share ?
_________________
V.W.owner since 1967

raygreenwood · Posted: Sat Aug 02, 2014 6:20 pm Post subject:

Im just starting mine this month. Fuel tank is still out right now with epoxy curing. But as I start practicing joins and bends I will be photographing the whole process. Also I will post some links in the next day to this thread of the videos and sites online.

Along the same lines of thought....but goes in a different thread....so this is a teaser Very Happy

I changed the duel filter on my 2012 golf today. And.... it is the same that many VAG cars use....and may be quite a good answer for a high pressure fuel filter AND primary fuel prezzure regulator in one.

The way it works is that all non turbo VW and audi use an inlet pressure to the inject9r rails ring....that is higher pressure than required ....4 bars...and the regulator and return line for that is in the filter....so it makes for super stable fuel pressure. There is an end of the rail standard return fuel pressure regulator that drops the pressure to standard injector level.

What this does is keep the pump pulsations about 8 feet away from the fuel rail. I tested running pressure.....and its .25 psi stable Shocked

.....awesome! (yes I have a very good gauge). These filters ...Mann brand...are about $23...and VW swears they are 50k miles filters....and after sectioning my old one today....I believe it. They have about 7X The filter area of yhe stock type 4 filter. I will start a new thread this week with pictures and a how to plumb diagram.....oh...and they were connected with nylon tubes. Ray

obnoxiousblue · Posted: Sun Aug 03, 2014 6:57 am Post subject:

Great read Ray, and glad you're back. Hadn't seen you around for a bit.

I'm VERY interested in these photos as you do yours.

I'm at the point where I need lines again and while I don't expect anything to be maintenance free, I'm a bit disappointed at the life of my original style braided lines.
_________________
Mike
1964 Beetle
2001 Eurovan Camper

nerdhotrod · Samba Member Joined: June 16, 2014 Posts: 49 Location: CT

I just replaced all the lines in my bus and the whole time I was thinking... Why am I not doing nylon :/.

I have this kit - www.amazon.com/Dorman-800-300-Quick-Disconnect-Repair/dp/B000XQ5IO4 and 3/8th line is only about 90 cents a foot. I bet you could do the whole job with a modern filter for less then 200 bucks and never have to worry about it again.

I'm 100% using nylon on my vtec mini project that's going together right now.

raygreenwood · Posted: Sun Aug 03, 2014 12:17 pm Post subject:

Mr. Unpopular · Posted: Sun Aug 03, 2014 2:16 pm Post subject:

Ray, what is your suggestion for connecting the nylon lines to the fuel tank? I have an EFI tank with the non-removable nipples on it.
_________________
"In any racing engine, the nearer you are to it disintegrating, the better it's performance will be"
-Keith Duckworth, creator of the Ford/Cosworth DFV

raygreenwood · Posted: Sun Aug 03, 2014 6:40 pm Post subject:

Are the nipples straight or do they have the single flare/bulge at the end? If they are straight like mine.....no bulge.....what I am planning to do is one of two things both of which I know will work:

1. get an adjustable die....no matter if its metric or standard. If the die will fit between the tubes.....you can lightly...about 1/3-1/4 actual thread depth. ..thread the outside of each tube. This is effectively knurling the tube. Read it in another forum somewhere. As long as the tube is a snug fit...then clamp it. No problem.

2. The other one that I am actually leaning toward is a steel high pressure union. Just like a brass low pressure union....it has a ferrule in the inside that slips over the tube and then it distorts and seal permanently. I used these on my 412 hydraulic clutch line coupling in the rear. They are good to about 1500 psi....so they will be fine for this.

On the outer end...just discard the nut and ferrule and connect to a female/barb fitting. Threads on with gas tape just to be sure of no leaks...and has the barb on the outer end for the nylon . You can also buy these type of fittings with a "ball seat" on the inside of the female/barb....so it seats in the pressure fitting just like the pressure union ferrule woild have.
With this fitting you can simply unbolt the lines from the tank when you need to without ever disturbing the pressure fitting.

I have also thought....if I had room....it would be cool to install a small ball valve on the feex and return right outside the tank so I can isolate the tank for fuel system work.

Edit: I just realized.....hilariously....that an AN steel or SS tubing pressure union is what I just described. Laughing

.....they dont have to be AN....but one would be perfect for the gas tank stubs....leaving a male thread on the outside to connect to a female barb fitting.
Ray


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