In cold weather fuel does not vaporize very well in the combustion chamber and this makes starting difficult.
Modern diesel engines designed for cold weather use a pre-heater or glow plugs. Glow plugs are heating elements that warm up the air that enters the engine. They work on a timed circuit or are manually activated just before the engine is started. The colder it gets, the longer those glow plugs need to stay on to preheat the combustion chamber for a smooth start.
Using the decompression lever on a diesel engine will open up the exhaust valve and keep it open so you can crank faster. Seconds later you release the valve and the momentum of the engine often results in higher compression and speed necessary for starting under difficult conditions.
Gasoline engines that use a carburetor also suffer from difficult starting on cold weather. The cold air and cold cylinder walls prevent the fuel from vaporizing correctly to permit combustion.
Using engine starting fluid is a very effective method to starting both gas and diesel engines in sub zero temperature.
Starting fluids are made from Ether and petroleum distillates blended together. This starting fluid has a low freezing point and easily ignites even at temperatures as low as -65 F. Many starting fluids have added lubricant and anti corrosive additives. You can buy a spray can at most gas stations and automotive stores. Use caution as it does not require much and over use often causes engine damage. It will void your warranty 100% and is easy to detect if it has been used.
Diesel fuel thickens in cold weather and has a tendency to gel. Diesel fuel has some naturally occurring paraffin (wax) and as the temperature drops, this paraffin crystallizes and affects the fluidity of the fuel and may cause hard starting and eventually lead to filter plugging. You can use a fuel additive to prevent this and is recommended year round.
Cold Weather – Batteries
Batteries that are weak may not crank the starter motor fast enough to start a cold engine. As the temperature goes down, so does battery capacity. A battery that has all of its power available at 80 degrees Fahrenheit will have only about 46% available power at 0 degrees Fahrenheit. Plus, the engine will be 2.5 times harder to start at 0 degrees due to thicker oil and resistance to movement of internal moving parts. In effect, an engine is about five times harder to start at 0 degrees Fahrenheit than at 80 degrees Fahrenheit. Test weak or suspicious batteries under load before cold weather to help eliminate potential problems during busy times. If batteries need replacement, always replace with a battery equal to or more powerful than the original battery.
Keep your battery stored indoors to prevent it from freezing. Consider buying a small battery charger / maintainer to keep the battery topped up so it is always ready to use.
Cold Weather – Oil
The warmer the engine oil is, the thinner it will be and have less resistance to moving engine parts. Make sure you are using the proper viscosity oil recommended for your engine for cold temperatures. If you cannot store engines inside or in a heated area, consider installing a block heater on the engine. To save time and electricity, put the block heater on an electrical timer set to come on a couple of hours before you plan to start the generator.
After starting the generator on a cold day, allow the engine to warm up a few minutes before putting it under load. Proper engine operation temperatures assure more efficient fuel combustion and may prevent damage to cold engine parts. Engine oil flows more readily at operating temperatures and allows proper lubrication of engine parts and areas.