Somebody mentioned FueLube, and that's what should be used. A workable
alternative is the old Aviation Form-A-Gasket, in the nonhardening
form, made by Permatex now. Silicones of any sort, or Teflon tapes,
are OUT.
Most guys are way too worried about fuel leaks. We're talking about
almost negligible pressure here, even in a pump system, and sealants
like FueLube will easily prevent leaking. In a past life I ran an air
brake rebuilding shop, and was forever getting back valves and
compressors with split pipe ports caused by beefy mechanics torquing
up the NPT fittings "just to make sure it don't leak." I found that
with a bit of sealant, the fitting wouldn't leak when little more than
finger-tight. This was with pressures ranging from 15 psi (coolant
systems) to 150 psi ( high-end air brakes). Even 1200 psi hydraulics
didn't need much tightening. Tight enough to prevent its shaking out
is enough, and vast amounts of goopy, dangerous sealants are totally
unnecessary.

Dan