My Onan DJC generator starts and runs fine, but sometimes does not build up to full voltage (it is setup for 240/120v single phase). When it does build full voltage it works fine as long as the generator runs. Then if it sits for a couple of weeks, the next time it is started, it may or may not produce full voltage. Today I started it and it was not producing full voltage. Measuring the voltage at the generator, it was producing 80 volts line to line, and 32/40 volts line to neutral. I suspect my voltage regulator may need to be replaced, but that is about a 300$ part and I want to have a good probability of solving the problem before ordering a new V.R.