It's worthwhile 'tracing' fuel line to fuel pump/then to carb and see how close to a heat source (exhaust manifold/header tube) it gets. Options (if too close) are to re-route the fuel line - or wrap it with insulation. On mine fuel lines (and break lines) in the engine compartment run sling the top of the chassis........not particularly close to a header tub.......I simply sourced some of that self adhesive aluminium cellular insulation/heat shield materia, cut to length required, then cut that about an inch or so wide, peel-off the backing, slide it under the fuel/or brake pipe and effectively wrap the pipe. Seemed to help mine.