ThunderFox

Hi guys,

Not sure if this is the right place to ask this, but it's been a week since I've done my engine swap. Today I pulled over on the side of the road to adjust my idle speed, when I noticed my brand new fuel lines seem to be "leaking".

Why I say "leaking", it's because they appear to be wet next to all the connections, be it on the pressure side or the return side, and both on the fuel rail and on the hard line fitting points.

Now, I've driven home stopping along the way to see if the pipes had moved or leaked any further, but they're still in place and the leak doesn't seem to be continuous.

As I've arrived home, I took a Q-tip to the leaking points and observed. It does not smell like gas, it has the consistency and color of engine oil I suppose. Doesn't smell like gas or oil.

Are the pipes supposed to, I don't know, "bed in" and leak some sort of gooey stuff? This is probably the stupidest question I've ever written haha. But right now I'm apprehensive about the whole situation, don't want the pipes coming off or causing a fire.

I will get some pictures to show the said leaks. I'm not confident in this, not one bit.

ThunderFox

Here are the pictures of the said pipes leaking:











Is this even a common thing to happen? I am so upset about this right now, I went through all the work to get the correct fuel hose and it's not working as it should in the end.

The hose I used is (as you can see from the photos): Original Birth fuel hose (DIN73379) 7mm inner, 13mm outer diameter.

Penny for your thoughts?

gjsmith66

Is that Type B or Type D? Type B is not rated for fuel injection...

I also would feel a lot safer using fuel injection hose clamps, that's what I used when I did my swap...

ThunderFox

Type B is cotton overbraid, so no, I know that one is for carburettor use or very low pressure solution.

This is the nylon internally braided one, guessing type D then.

But I think I've got it figured. The diameter is wrong: Should be 5/16 inch (that is around 8mm) and this one is 7mmx13mm.

I'll just look around for the correct diameter hose since this is not the correct one it seems.

gjsmith66

I used GATES 27348, which worked perfect.

Then get some AAS 5/16" Fuel Injection Hose Clamps

ThunderFox

How are those fuel hose clamps?

gjsmith66

As the image reveals, the AAS injector clamp has a solid band that eliminates cuts made by a slotted worm-gear band. Not obviously visible in the image is that the band of fuel injection clamps is flared away from the hose which eliminates the sharp corner of the band digging into and potentially cutting the hose. The fuel injector clamp draws the wings of the band together as tight as one wishes (a must on fuel injection lines).

codrus

AAS fuel injection hose clamps:

AlwaysBroken

The sight of fuel lines without clamps scares me for some reason.

IIRC (it's been quite a few years) I switched to aeroquip 1503 hydraulic hose (it's got layers of woven steel and nylon with rubber inside) when I got tired of the regular hoses abrading or wearing out. It's stiff as hell, but it has shown no signs of wear or degredation whatsoever. I don't remember which size I used- I suppose I could put a caliper on the fuel lines when I get home tonight if anyone wants to know.

curly

iTrader: (25)

Good thing he didn't picture any without clamps.

AlwaysBroken

What's that circular thing with the braided line going into it?

NiklasFalk

iTrader: (1)

FPR

gjsmith66

And the braided line is the vacuum line, fuel line is underneath, with a clamp.

AlwaysBroken

Ahh ok, my bad.

ThunderFox

That's correct, the nylon braided hose you see there is just a 4mm hose for the FPR vaccuum

You may also see some unclamped smaller hoses in the picture which go to the MAP sensor on the Megasquirt. All the fuel hoses (they're just two) are properly clamped on both ends using the OEM clamps.

Yesterday I went to the place that sold me those pipes and tried to get some information on them from the spool it came in. Luckily, they still had the empty spool, as I had bought the rest of the pipe they had. This pipe is rated for use up to 10 BAR it seems, so it should do. Maybe it's the clamps that, although they feel tight and don't move by hand, are not clamping with the force they should. I'll replace them with the fuel hose clamps you mentioned before.

Cheers!

ThunderFox

Okay, so to close this up, bought some ABA clamps for 13mm fuel hose, that seems to do the trick! They're now tight. Also added the OE sleeving to the pipes so they don't rub anywhere.

As I took the pipes out they appeared to be in good condition, even cut an inch off of one just to look "inside" and see if it was damaged. Nope. All appears to be in good nick.

I'm still really curious about the gooey stuff that was leaking. It was definitely not gasoline. On the fuel rail inlet pipe, it was where that stuff leaked the most. When I touched it, it was a brown substance, no smell whatsoever, with the consistency of grease. But the pipes were not greased out before putting them in the car. Some strange reaction has happened there but I can't figure out why. Maybe it's something in the "intermediate" layer of the pipe where the nylon braid is?

ThunderFox

Photos of said clamps in place:





Here's an "autopsy" of that inch I cut off of one of the pipes. Doesn't look bad and doesn't look like there was some gooey stuff in there either...



Cheers!

Joe Perez

iTrader: (8)

I'm not familiar with DIN ratings or Birth fuel hose.

However, with SAE fuel hose here in the US, there are certain hoses rated specifically for use with fuel injection, as opposed to with carburetors or on the low-pressure side of fuel injection plumbing. Whether this has to do only with their bursting strength or implies something about their permeability at high operating pressure is something I do not know. But I have only ever used hose with this rating, and I have never seen this sort of grease-like byproduct that you are describing.

ThunderFox

From what I've researched on this particular hose, it's made for low pressure injection systems (< 10 BAR) and has a burst resistance of 30 BAR. It also said it was suitable for all kinds of fuel except biodiesel.

I'll keep an eye on it from now on. At least now I can be sure the pipes won't pop out with these hose clamps. If I find there's strange leakage again, I'll just replace the hoses altogether, it's not that hard or expensive to do.

Cheers!