I know things... A lot of things.
Join Date: Feb 2015
Motorcycle: GSXR 750 K4
Re: Fuel pump or stator?
If "battery voltage at rest" was the voltage at the battery with the bike switched off after sitting a while and you found it to be 14.99V then you're either not measuring correctly, or something weird is going on. If you measured with the engine running and you find the voltage to be at ~15V at idle but fall below 12V at 5000 rpms, then either something is wrong with your stator, as suggested, or perhaps your splices do not establish a connection of sufficient quality to pass the higher current at higher engine speeds. Since the problem started after redoing the splices, I'm leaning towards the latter.
At any rate, it would probably be a good idea to undo the splices, measure the stator output and resistances, as described in the manual to see whether it's within spec and, if it is, redo the splices properly. The important thing there, is to make sure that the area of contact between the two spliced ends is large and clean. This means, apart from making sure the ends are clean, that if a clamp is used, it needs to make contact with a large part of the wire and be properly tightened. Alternatively, if solder joints are used, care must be taken to ensure that the solder has permeated the strands of the spliced ends, instead of forming a (perhaps loosely attached) jacket over them.