Most diesel engines are hard to start when it is cold. Plugging the diesel engine block heater in will help the engine start.
It is not so much hard for a car to start when the engine is cold as it is easier for a car to start when the engine is warm.Cars that are hard to start in the cold are usually not new cars any more and because of wear and tear there is more likely to be something that doesnt work as well. when fuel is warm it ignites more easily.
Makes it hard to start and run poorly.
Onan no longer makes engines. But with the older ones it is hard to say. Both had very good engines. Some better than others. I would say Kohler had the better single cylinder engine after Onan stopped making the LK. Onan had better RV generator engines. On the larger units they were both the same in quality and support.
It may be set to run too richly, or perhaps it's trying to "vapor lock". Have the engine tuned up by a professional to start with, then see if the problem still occurs.
Timing needs adjustment is the most likely cause.
Well depends of what kind of hard start and transmission your car may have. It can be and electrical, transmission, engine issue
Fuel may be draining back into the tank. So the engine will turn over but not start until the fuel reachs the engine. If it is damp out, the wires may be bad. The spark will arc before it gets to the plugs, preventing combustion. It takes fuel, spark and combustion to make an engine run.
Need more info like the year and engine size.
If there is no check engine light illuminated, start with the basics like a good tune up.
The engine won't start or will be hard to start in cold weather unless you have the motor heater plugged in.
Need more info such as the year, engine size and what color smoke.