Diethyl ether, with a small amount of oil, a trace amount of a stabilizer and a hydrocarbon propellant, has historically been used to help start internal combustion engines because of its low 160 °C (320 °F) autoignition temperature. Some current products sold as starting fluid are mostly volatile hydrocarbons such as heptane, (the main component of natural gasoline) with only a small portion of diethyl ether, and carbon dioxide (as a propellant). It is often useful when starting direct injected diesel engines or lean burn spark engines running on alcohol fuel. Some formulations include butane or propane as both propellant and starting fuel.
Starting fluid is sprayed into the engine intake near the air filter, or into the carburetor bore or a spark plug hole of an engine to get added fuel to the combustion cylinder quickly. Using starting fluid to get the engine running faster avoids wear to starters and fatigue to one's arm with pull start engines, especially on rarely used machines. Other uses include cold weather starting, vehicles that run out of fuel and thus require extra time to restore fuel pressure, and sometimes with flooded engines. Mechanics sometimes use it to diagnose starting problems by determining whether the spark and ignition system of the vehicle is functioning; if the spark is adequate but the fuel delivery system is not, the engine will run until the starting fluid vapors are consumed. It is used more often with carbureted engines than with fuel injection systems. Caution is required when using starting fluid with diesel engines that have preheat systems in the intake or glow-plugs installed, as the starting fluid may pre-ignite, leading to engine damage.
Starting fluid is not recommended for regular use with some two-stroke engines, because it has no lubricating qualities. The lubricating oil for these engines is either mixed with the fuel or injected near the fuel intake of the motor. There is also a risk of igniting the mixture in the crankcase. Engines that require premixed gasoline and haven't been run recently are especially in need of the mixed lubricating oil because oil can dry off internal parts over time. WD-40 was previously recommended for use on two stroke engines because it has lubricating qualities, however, the formulation with CO2 as propellant instead of propane no longer has the same effect.
Diethyl ether has a long history as a medical anesthetic; when starting fluid was mostly ether, a similar effect could be obtained using it. Use at the present time directly as an inhalant includes the effect of the petroleum solvents, which are more toxic as inhalants than diethyl ether.
Sometimes referred to as "passing the shirt," the starting fluid is sprayed on a piece of cloth and held up to one's face for inhalation. This trend has gradually picked up since the turn of the century, as phrases such as "etherized" and "ethervision" have gained popularity. The effects of inhalation vary, but have been known to include lightheadedness, loss of coordination, paranoia, and sometimes hallucinations.
- Popular Mechanics, 1921, p. 781
- "Ethyl Ether". Wolfram Alpha LLC. Retrieved 30 May 2013.
- "CRC JUMP START Starting Fluid" (PDF).
- "NAPA Premium Starting Fluid".
- Glow plug / starting fluid controversy....... http://www.thedieselstop.com/archives/ubbthreads/73IDI/showflat.php-Cat=&Number=518386&page=137&view=collapsed&sb=5&o=&fpart=1.htm. Retrieved 2 January 2014. Missing or empty
- "How to Start a Diesel Truck". WikiHow. Retrieved 2 January 2014.
- Product information for different types of ether starting fluid provided by a manufacturer, Spray Products Corp.
- MSDS for a 50% ether fluid
- MSDS for 11% ether fluid