2001 RX DI and 2002 GTX DI both have problems.

[AZSPEED]

just bought both skis and trailer for 3k. They have 40 hrs on them very clean. Problem was i could not start them when I bought them due to bad batteries. So I took a chance, well put new battery in GTX and started right up had older battery that I charged up and put in RX. Tried to start and starter spins but will not engage. Went to lake with GTX and ran great for about 20 min then maint light and beeper came on, well I had browsed this forum for a couple days after buying the skis so I had a couple ideas. the ski went into limp mode when light and beeper came on rode it a little and then the low 12 v came on. So I figure the Reg/rect is probably bad. and on the RX I'm going to try a new battery hope that takes care of it. Both look like they could use wear rings also, will do that this winter.
I am going to be using these with my wife to cruise around, couple questions, can you upgrade to bigger batteries? looks like an optima car battery would fit tons of room used to riding standups.
Are all the electronics in these skis nescessary for them to run? I now they are fuel injected but it seems like an awefull lot of wiring for a ski.
Does it hurt the ski if you dont run the DI oil, the guy I got them from just ran the yellow bottle sea doo oil.
Any other tips to help me out, Mods parts or accesories to make them better or more reliable.

 

[DooWacka]

I would agree that the Rec/Reg is probably bad, the DI's can tend to do that. Measure the volts to the battery when running, and if not between 13-14.5v, then it is probably shot. If you keep the battery mostly charged up then it is easier on the Rec/Reg since it doesn't have to charge so much. I don't know why you would need a bigger battery considering the weight, the unbalancing, with no real advantage, since the DI usually starts very easily.
All of the wiring is pretty much needed, except maybe compass, air & water temperature. There are several sensors the MPEM requires to make the calculations for the air and fuel injectors.
Seadoo just recommends the full synthetic XPS oil for the DI, and there is no longer a special DI oil. I would stick with the full synthetic and not the blend that is run in other Doos.
The DI is pretty much already a screaming machine, so the only mod for better reliability could be an aftermarket Rec/Reg that would stand up better.