The fuel supply system, from tank to fuel rail, is pressurized to 2.5bar
(eta) or 3.0bar/42psi (i engine) in normal operation. If there is a
clog the pressure can go as high as 150psi, even in the normally
low pressure fuel return system.
This pressure requires heavily reinforced fuel line. Most of the bulk
hose that you find at auto parts stores is only lightly reinforced and
is intended for gravity feed or low pressure fuel system (3-6psi). That
type of hose will quickly balloon and fail.
8mm (or 5/16", 7.94mm) ID high pressure hose, 13mm OD
You'll need 9 ft/ 3 meters total for most models, 11ft with fuel cooler
2 pcs 4ft engine comparment supply and return
2 pcs 6" fuel filter inlet and outlet
13-31-1-469-781 Fuel hose, bulk 1 meter
You'll find a wide price range: $10/meter Pelican
$1.75/inch at some dealers, $6.49/meter at EAP
07-12-9-952-104 L12-15 hose clamp, $0.70
Use rounded edge hose clamps. BMW prices are very reasonable.
Molded hose sections
16 12 1 180 398, fuel filter hose (inlet), sugg US retail $5.17
16 12 1 180 399, fuel filter hose (outlet), sugg US retail $8.00
13 31 1 722 565, fuel rail inlet [fuel hose 561-920 mm], sugg US retail $26.68
16-12-1-180-237, fuel filter hose clamps, sugg US retail $0.33
Superceded by 07-12-9-952-104