I was called to 3 residences. 2 of the units were less than 4 years old and one was a 2013 model. All 3 were continuing to operate but hunting or surging constantly after about 2 to 3 minutes of normal running. Would continue to surge even with gen main breaker open. I used a monometer on 2 of them and the problem was before the generator. All regulators were free of snow, but temps were about 0F wind chills. Blowing snow and 20 mph winds. I figured the problem was primary tank regulators. All 3 tanks had at least 70% fill. I tried warming up regulators and it helped a bit, but did not end problem.
here’s the kicker. By turning the fuel selector knob about 1/6 to 1/4th the way towards natural gas side the unit ran great. 60 HZ, 240 V output and averaged 3600 rpm under load.
if I tried to turn it back to full propane...it surged.
im at a loss. I left the settings to allow operation throughout outage... figured it can’t hurt. But I’ve never seen this before.