[Merv and Sharon]

This really sounds electrical Cameron. Relays are usually robust altho the connections can corrode (that spray from Dick Smiths for cleaning electrical connections is useful sometimes). Fuses are real culprits and there is often a single fuse in the power in to the computer. That is one to check. How about you put a couple of pics of your motor up and we might know more? I assume you have checked that the spark plus are getting spark?