my little sister has a 90 crx and it has been doing this wierd thing where sometimes it will not start my dad has repalced the cap, rotor, plug wires, plugs, coil, fuel filter. It still seems to have the same issue. here is the wrinkle it starts everytime with the fuel cap off.

I am at a loss but it seems to be a fuel issue. mebe FPR or fuel pump relay?