Starting fluid is a mixture of volatile hydrocarbons (heptane, butane or propane), 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. Starting fluid works due to the low autoignition temperature of diethyl ether: 160 °C (320 °F)
Starting fluid is sprayed into the engine intake near the air filter or into 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 sometimes with flooded engines. Mechanics sometimes use it to diagnose starting problems. If sprayed into the air intake on a car, it can be used to determine whether the spark and ignition system of the car is functioning and the fuel delivery system is not, since the engine will run until the starting fluid vapors in the intake system are exhausted. It is used more often with carbureted engines than with fuel injection systems. It is not recommended for starting some diesel engines that have preheat systems in the intake or glow-plugs installed as this may lead to damage to the engine.
Starting fluid is not recommended for some two-stroke engines, because it has no lubricating qualities; similar to unmixed gasoline. 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. Carburetor cleaner such as gum-out brand contains a lubricant and will also act as a starting fluid. Regular starting fluid will not damage an engine that is properly lubricated if used sparingly and only for starting. Do not run any two-stroke engine for extended periods of time on starting fluid, especially engines that require premixed gasoline and those that haven't been run recently because oil dries off internal parts over time. WD-40 was previously recommended for use on two stroke engines because it has lubricating qualities, however, after the propane was removed as the propellant and replaced with CO2, it no longer has the same effect.
Starting fluid is sometimes used as an inhalant. 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.
- 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