I am going to be installing an automotive ignition module that is commonly used to see if it the electronics pulling revs out. Pick it up tomorrow.
Also any clues on the max rpm of the motors? I thought it would be arround 4800 - 5000rpm.
Just a thought, if I tested it on the trailer and it revs up to 5000 then it would not be an electronic rev limiter but another fault? Might test it tonight.