Hi,
I have installed 5/16 hoses on more than 30 vans last year with expensive
5/16 FI clamps (be careful with cheap ones), i find 1/4 hose to be to tight
and those have cracked on at least one job i did 2 years ago.
Lately i use Cohline-2134 7,5 X 13,5. I find that this one is perfect.
i buy them per 100 feets roll.

Lately, i have problems with fuel rails, some are old and wile working on
them out of the van, they crack! or leak after i put them back in the vans.

Buy the most expensive hose you can find, cheap one will crack after 6 month
to 1 year. My cost price is 5,20$ per feet. So anything that retail under 5
is crap.

Ben
http://www.benplace.com/fuel_line.htm