Have you got a haynes manual? have a look at the g40 wiring diagram, i remember a wire being connected between the ecu relay and something to do with the ignition system (sorry to be so vague) but that may be why you would have no spark but power to the coil
then again if the fuel pump is working but no spark, it may be something else
when you say the fuel pump is working, do you mean when you turn the ignition on it primes?
have you tried taking the dizzy off, but keeping all the connectors on. then turn the dizzy by hand and listen for the fuel pump? if theres a problem with the wiring to that, it would cause no spark (make sure you mark the dizzy before you remove it)
not sure what else to suggest
is the ecu relay definitely latching across when you turn the ignition on?
found this photo of mine before i changed my relay and swapped all the wiring
its the wiring order for the original relay,ignore the dodgy wiring, it wasnt me and its all sorted lol