I asked a co-worker and he said the generator shouldn't make a difference - he suggested it might be a vibration problem, with vibration from the engine causing an intermittent connection, either in the power wire, the ground wire, or internal to the radio.
The other possibility is the voltage briefly dropping below 11 or above 16 and the radio sensing it and shutting off, but that seems unlikely.
That said, I haven't owned any generator cars, so am not totally certain of that.
Could it be that generator is putting out enough volts without the engine running, but with the engine running there aren't enough amps to go around?
Well, the generator doesn't put out any volts without the engine running, but yes, it could theoretically be possible that the ignition system and other accessories take up all the available amps and there isn't enough left with the engine running to supply typically 2-3 Amps (I would think) to the radio. You said you are getting 13.6 at the radio lead - was that with the radio disconnected? If so, what do you get across the battery or on the power line to the radio with the radio running.
Check your ground connection also - although that would typically affect the engine off running as well.
2002 Ford Focus Sony CDX-GT410u Sony XT-100HD HD Tuner Stock speakers, no amp, no subs
DonCommunity Manager