I have worked on my Onan several times. I changed the points, fuel pump and filter, cleaned the carb. The Onan runs for hours with no issues when not driving. Once I drive for a couple of hours the Onan will not run right if at all. It surges and stops when driving. I just got back from a long trip. I checked the Onan the next day after the trip an it ran fine yet it would not run hardly at all when I tried to use it when stopped to eat or when it got hot in the RV. I have tried a different coil and it did the same thing on another trip. We generally have 2 cats and my wife gets up set if it gets over 85 in the RV. My dash AC is worthless so I would like to be able to run the house AC on hot days.

Since it will run ok for about 1.5 to 2 hour for the start of a trip, I wonder if gas in the tank has warmed up and is creating the problem. I tired to adjust the carb when the generator is acting up. I could not get it smooth out. If I had thought about it at the time, I would have change the coil to see if that helps.

I had another smaller Onan generator. Are the control boards the same on a 4KW as a 7KW generator. If so I will change the control board and see what that does. I guess the other thing could be carbon in the heads and the running temperature has gone up on the road and is causing the problem. I just do not know were to start. I know it runs better since I replaced the fuel pump a filter points and coil when running off the road.

Thanks

Art & Doris
76 EL