I have a 4kw Onan. I noticed when I have it running and put a load on it (AC, micro, hairdryer) it doesn't increase in RPM. You can tell it has a load on it but it pretty much keeps the same RPM. I have had it down and I serviced it with plugs and things and have messed with the adjustment for the mechanism to sense the load but it still seems to not change. Is this normal? The outlet shows 110 with and without a load. thanks