chris flannagan
I checked my 8KW and there is a RPM Sense Loss error. I replaced the battery 2 months ago and took it last night to be tested under load and it passed. I cleared the code and put it in manual mode and the read out says cranking and then shows RPM sense loss. during the time it says cranking the generator does nothing. It does not try cranking. That is why I tested the battery.

Any suggestions?
Check voltage at starter and start contact relay. Loose wire or bad control board!
The 8KWs have a fire wall mounted starter solenoid which is prone to failure.  The easiest test would be to check to see if you are getting at least 10 VDC at the starter cable bolt when it says it is cranking but is not.  If you do it is a bad starter if not a bad solenoid.  You should also check the #56 wire at the solenoid just to make sure it is getting 12 VDC when it is supposedly trying to crank, if not then either a wirring issue or a controller issue.
Hi Chris,  I had a similar issue a short while back with a RPM Sense Loss Error led that showed up on our 8kW. 
A lot of good people here guided me through a process and we had a successful outcome.
You can see the post here in the Ziller Forum under: 8kW 55010, Serial 5244008 J2-3 Wire #14 . 
I hope that this will be of some help.
The most common problem I see is a faulty starter solenoid, if you reference the posts that marcob suggests you will get some good diagnostic ideas.