Fridges pull a lot of watts, so does a water heater. May be too much for it.
Might work with just one of those off line.
I got a 6500 watt generator. it was running fine for about 35 min then shuts off.....pulling fridge and water heater off it and cable modem......has oil, plenty of gass.... bought new a few hours ago.
ok found the problem...was running too much to each individual power outlet on it... once I spead everything out over all 5 outlets the problem solved.....however.... in the last 10 min I got power back so seriously that was a pain in the ass....had to drive from the jersey shore to philly to find a generator.