[alfa] RE: 164 up in flames

["Graham Davis" <grahamldavis@xxxxxxxxxxx>]

Jeff Matson wrote:

I noticed that someone mentioned purchasing replacement fuel injection
hose for $1.00 a foot.  This is either a really good deal, or may not be
injection hose.  I believe that SAE 30R7 is low pressure line
(carburetors, etc), and that SAE 30R9 is the high pressure fuel
injection line.  I pay over $5 a foot for this stuff at my local
discount auto parts place.  I would double check what you've got, as you
want the higher rated stuff for this purpose.

and Joe Elliott wrote:

I'd say that you're pretty lucky to have gotten 32000 miles out of
it.  That's the hose that's frequently blamed for fuel leaks in
European cars that are supposed to have 7.5mm fuel lines.  It's the
wrong size, and the wrong spec.  30R7 is only rated to 50psi working
pressure.  That doesn't give you shit for factor of safety.  If you'd
gotten high-pressure EFI hose (SAE 30R9) at AutoZone, you'd notice
that it's actually more expensive than getting it in the proper size
from a BMW dealer.  I don't mean to be an ass, but I've seen this
stuff installed on these cars, and even when it doesn't leak, it
deteriorates very quickly.  Even if it didn't deteriorate, I hate to
think what would happen if the regulator failed (not unheard of) and
the fuel rail pressure jumped over 50 psi.  (In case anyone cares, I
do feel safe using 30R7 in the wrong size for the RETURN line, since
the pressure isn't as great and there aren't any of those push-on
connectors involved.)

Well, it seems I've touched a hot button - no pun intended. 

Gentlemen, while there are obviously differences of opinion here, please
be advised that I first did my homework.  On L-Jet systems, the injector
and fuel rail hose barb necks measure 8mm dia. while the barb shoulders
(2 on each) measure 10mm dia.  The primary issue on disassembly is not to
score the barbs (duh - that's why the factory manual recommends burning
the hose off the barb with a soldering iron).  Obviously, 7.9mm hose IS
working for me and others in my local chapter but if you need that extra
.4mm (  Motronic systems use 8mm steel tube with a rolled end-bead of
10mm dia. and crimp-clamps vs. cups.  SAE 30R7 fuel injection hose does
indeed have a working pressure of 50 psi (thank you Joe and nobody is
calling you an ass) but has a minimum burst pressure of 250 psi, a
working temperature range to 250 degrees F. and a minimum bend radius of
2.5 inches - important in routing to the cold-start injector.  Both of
these fuel systems are regulated to between 30 & 35 psi and while a
blocked pump could deliver a maximum of 85 psi. that still represents a
3/1 safety ratio; good enough for me and the price is right. 

On the issue of my international-Italian car, I neglected to mention the
Sanden AC compressor (Japan, now manufactured in Singapore).  Don't wish
to leave anyone out.

Graham L. DavisSt. Louis, MO</DI
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