Find why FSX engines won't start or keep running, with fixes for fuel, mixture, ignition, Ctrl+E, controller conflicts and add-on procedures.
In FSX and FSX: Steam Edition, engines usually refuse to start or immediately stop because fuel is unavailable, the mixture or fuel lever is at cut-off, ignition is off, the wrong engine is selected, or a controller keeps overwriting the controls. Default aircraft should normally start with Ctrl+E; complex add-ons may require their own checklist.
What should I check first?
For a default FSX aircraft, check the fuel supply and cockpit control positions before changing files or reinstalling the simulator.
- Confirm that fuel is aboard. Open the Fuel and Payload window and check that the aircraft has usable fuel. Set the fuel selector to BOTH, ON or a tank containing fuel, as appropriate for the aircraft.
- Set piston-engine controls. Put the propeller control fully forward, set the mixture rich and open the throttle slightly. At a high-elevation airport, an excessively rich mixture can prevent starting, so lean it gradually if the engine cranks without firing.
- Set turbine controls correctly. Leave the throttle at idle and keep the fuel or condition lever at cut-off until the starter has produced the required engine rotation. Introduce fuel at the point specified by the aircraft checklist.
- Turn on the required systems. Piston aircraft normally need battery or master power to operate an electric starter and the magnetos set correctly. A manually started jet may also need an electrical source, ignition and pneumatic start air.
- Try automatic start. Press
Ctrl+Ein a default aircraft. Our FSX keyboard command reference lists the associated engine, mixture, magneto and starter controls. - Check every connected controller. A mixture axis at idle cut-off can cancel the keyboard start command as soon as the device sends another input. Temporarily unplug the controller or remove duplicate throttle, mixture, propeller and engine assignments.
What does the starting symptom tell me?
The point at which the start fails usually identifies the system responsible.
| Symptom | Likely cause | What to check |
|---|---|---|
| No propeller movement or starter rotation | No electrical power, wrong engine selected, missing control assignment or add-on interlock | Battery and master switches, engine selection, starter command and aircraft-specific start conditions |
| Engine cranks but never fires | No fuel, mixture at cut-off, ignition off or incorrect jet start sequence | Fuel quantity and selector, mixture or fuel lever, magnetos, ignition and fuel introduction |
| Engine catches and immediately stops | Controller axis override, empty selected tank, insufficient idle power or fuel lever returning to cut-off | Hardware axes, fuel selector, throttle position and per-engine levers |
| Only one engine starts | One engine selected or controls assigned per engine | Select all engines and compare each engine's fuel, starter and ignition controls |
| Engine stops as power is increased | Fuel starvation, incorrect mixture, condition-lever position, controller calibration or an active failure | Selected tank, fuel pressure, mixture, axis movement and failure settings |
Why does the engine start and then stop?
An engine that starts but dies within seconds is usually being deprived of fuel or receiving a new cut-off command from an input device.
- Mixture-axis override:
Ctrl+Emoves the virtual mixture, but touching a physical throttle quadrant can send it straight back to idle cut-off. One mistake we see constantly is the same mixture axis assigned on two devices. - Empty or closed fuel supply: Check both total fuel quantity and the tank actually selected. Fuel in the opposite wing does not help if the engine is drawing from an empty tank.
- Throttle fully closed: Some aircraft need the throttle cracked open to maintain idle after firing. An add-on may also model idle-stop or fuel-control behaviour absent from default aircraft.
- Ignition switched off: A hardware magneto switch can overwrite the virtual cockpit position when the starter is released.
- Aircraft-specific protection: Detailed add-ons may shut an engine down after an incorrect start, low fuel pressure or an omitted pump, valve or generator step.
On a conventional piston aircraft, switching off the battery after starting does not normally stop combustion because the magnetos are self-powered. If the engine dies, inspect the magnetos, fuel supply and mixture rather than assuming the battery alone caused it.
Why doesn't Ctrl+E start the engines?
Ctrl+E is a diagnostic shortcut for default FSX aircraft, not a guaranteed replacement for the start procedure in every add-on.
If a default aircraft ignores it, confirm that the shortcut is still assigned to automatic engine start. Our guide to finding and changing FSX control assignments explains how to detect remapped commands and conflicts between devices.
If only one engine responds, select all engines before trying again and inspect any per-engine mixture, condition or fuel-lever assignments. Complex aircraft can intercept or disable automatic start because their custom systems require a battery, APU, bleed-air source or cockpit start panel to be configured first.
Do piston and jet engines require different fixes?
Piston and turbine engines fail to start for different reasons, so use the checklist for the aircraft type rather than applying one sequence to everything.
| System | Piston aircraft | Jet or turboprop |
|---|---|---|
| Fuel control | Fuel selector and mixture | Fuel pumps, valves and start or condition lever |
| Ignition | Magnetos and starter | Ignition system plus starter and start-air source where modelled |
| Control position | Throttle slightly open; mixture rich or adjusted for altitude | Throttle at idle; introduce fuel after adequate rotation |
| Common mistake | Mixture at cut-off or selector on an empty tank | Fuel introduced too early, no start air or condition lever left at cut-off |
For the complete switch order, use our cold-and-dark engine start and shutdown walkthrough. The default airliner has its own sequence, covered by our detailed FSX Boeing 737-800 checklist.
Why does the engine quit during take-off?
An engine that idles correctly but stops when power is applied points to fuel delivery, mixture, hardware calibration or a simulated failure rather than the starter system.
- Verify that advancing the throttle does not also move the mixture or condition lever.
- Check that the selected tank contains fuel and that crossfeed or fuel valves are configured correctly on multi-engine aircraft.
- Adjust piston mixture for airport elevation; both excessively rich and excessively lean settings can cause poor power or shutdown.
- Check for carburettor icing where the aircraft models it, particularly after prolonged low-power running in suitable weather.
- Clear active engine failures and inspect any add-on maintenance or damage system.
What is the fastest way to isolate the fault?
A clean default-aircraft test separates an FSX control problem from an add-on procedure problem in a few minutes.
- Create a new flight rather than loading a saved cold-and-dark situation.
- Select a default single-engine piston aircraft, add fuel and clear any active failures.
- Temporarily disconnect external controllers.
- Start the engine with
Ctrl+Eand let it idle for at least a short period. - If it stays running, reconnect controllers one at a time, then test the original aircraft. The fault lies in an assignment, saved state or aircraft-specific procedure.
- If it still stops, restore the default keyboard controls and repeat the test before changing FSX configuration files.
Reinstallation should be the last resort. It rarely fixes an empty tank, a mixture command stuck at cut-off or a custom aircraft that requires its own start logic.