Do modern diesel engines have any electronic components?

Some motor yachts do, but most (especially sailing yachts) continue to apply the KISS (keep it simple stupid!) design principle. Engines on sailboats are considered emergency equipment by most and as such, you don't want a situation where you don't have an engine because a microchip burned out. The major advantage to diesels is their extreme relniabliliy, and electronics would undermine this advantage. (Diesel engines don't require any electricity (a diesel will run until it's starved of fuel: you must close the fuel valve, usually held open by a solenoid, but if the solenoid fails open, then you have to find another way to starve the beast!) so the voltage regulator is part of the alternator circuit, and has only a periphery roll in regard to the workings of the engine).