I may be wrong but to me it sounds like some wiring has chaffed through and is shorting on the chassis, engine, or some other metal part. That may be the reason for the interference on the radio. Also sparks and fuel may not go well together.
I would disconnect the battery, get a good torch, plenty of time, and have a very good look around for damaged insulation on a cable loom.
What got disturbed on the maintenance? Try looking there first.
But I could well be wrong