Fix FSX engines that won't start or stay running: check fuel, mixture, ignition, Ctrl+E, controllers, saved states and the default 737.
In FSX and FSX: Steam Edition, engines usually will not start or stay running because fuel is unavailable, mixture or fuel levers are at cut-off, ignition or start power is missing, the wrong engine is selected, or a controller overrides the cockpit. Test a default aircraft with Ctrl+E, then match the symptom below.
Engine not starting: what should I check first?
Check the controls that govern fuel and combustion before changing files or reinstalling FSX.
- Confirm that usable fuel is aboard. Open the Fuel and Payload window and inspect the individual tanks, not just the total quantity. Set the fuel selector to BOTH, ON or a tank containing fuel, as appropriate for that aircraft.
- Set piston-engine controls. Put the propeller control fully forward, move the mixture towards rich and crack the throttle open. At a high-elevation airport, full-rich mixture may be excessive; lean it gradually if the starter turns but the engine will not fire.
- Set turbine controls correctly. Leave the throttle at idle and the fuel, condition or start lever at cut-off until the starter produces adequate rotation. Introduce fuel at the point specified by the aircraft checklist. Adding fuel too early can cause a hot or failed start in detailed add-ons.
- Provide ignition and starting power. A piston aircraft with an electric starter normally needs master power and correctly positioned magnetos. A manually started jet may require battery or external power, an APU, ignition and pneumatic start air.
- Try automatic engine start. Press
Ctrl+Eonce and allow the sequence time to run. Our FSX engine and keyboard command reference lists the associated starter, mixture, magneto and engine-selection controls. - Check which engine is selected. An earlier engine-select command may have left FSX controlling only one engine. Compare the fuel, ignition, starter and lever positions for each engine.
- Eliminate controller overrides. Disconnect throttle quadrants, joysticks and other controllers before starting FSX, then repeat the test. A mixture axis resting at idle cut-off can undo
Ctrl+Eas soon as the device sends another input.
What does the failed start symptom tell me?
The stage at which the start fails usually identifies the system responsible.
| Symptom | Likely cause | Check next |
|---|---|---|
| It does nothing: no propeller or starter rotation | No electrical or pneumatic start power, wrong engine selected, missing command assignment or add-on interlock | Battery and master switches, APU or start air, engine selection and starter binding |
| Starter turns but the engine never fires | No fuel, mixture at cut-off, ignition off or incorrect turbine sequence | Selected tank, mixture or start lever, magnetos, ignition and fuel introduction |
| Engine catches and immediately stops | Controller override, closed fuel supply, insufficient idle throttle or lever returning to cut-off | Hardware axes, fuel selector and per-engine controls |
| Only one engine starts | One engine selected or separate per-engine assignments | Engine selection and each engine’s starter, mixture and fuel controls |
| Engine stops when power is increased | Fuel starvation, incorrect mixture, cross-assigned axes, active failure or add-on damage | Fuel source, mixture, controller movement and failure settings |
Why does the engine start and then immediately stop?
An engine that fires and dies within seconds is usually losing fuel or receiving a new cut-off command.
- Mixture-axis override:
Ctrl+Emoves the virtual control, but a physical mixture lever at minimum can send it straight back to cut-off. Duplicate mixture assignments across two controllers are a recurring cause. - Wrong or empty tank: Fuel in another tank does not help if the selected tank is empty or its valve is closed.
- Throttle fully closed: Some piston aircraft need the throttle opened slightly to sustain idle. Detailed add-ons may also model an idle stop or separate fuel-control gate.
- Magneto switch overwritten: A hardware ignition switch can return the virtual magnetos to OFF when the spring-loaded start position is released.
- Aircraft protection or damage: A complex add-on may shut down after low fuel pressure, a hot start, an omitted pump or valve step, or a failure recorded by its own maintenance system.
Switching off the battery after a conventional piston engine starts does not normally stop combustion because its magnetos are self-powered. If it dies, investigate the magnetos, fuel supply and mixture rather than treating the battery as the only cause.
Why doesn't Ctrl+E start the engines?
Ctrl+E should start the default FSX aircraft, but it cannot overcome a missing assignment, a controller holding fuel at cut-off or custom add-on logic.
Check that the automatic engine-start command is still assigned and is not duplicated or replaced. We explain how to inspect and restore FSX keyboard assignments without guessing which binding changed.
If only one engine responds, restore control of all engines and inspect any per-engine axes. If a default aircraft starts but an add-on does not, stop treating Ctrl+E as the test: the add-on may require its own battery, APU, bleed-air, fuel-pump and cockpit start sequence.
How do I start the default 737 in FSX?
The default FSX Boeing 737-800 should normally respond to Ctrl+E; failure in that aircraft usually points to fuel state, control assignments, engine selection or a hardware override.
For a manual cold-and-dark start, establish electrical power, start the APU, provide APU generator power and bleed air, configure the pneumatic system for starting, and place one engine start switch to the ground-start position. Once N2 is rotating adequately, move that engine’s start lever from cut-off to idle and monitor EGT, oil pressure and stable idle before starting the other engine.
After both engines are stable, transfer electrical and pneumatic loads as required by the checklist. Our cold-and-dark FSX starting sequence covers the switch order and the differences between piston and turbine aircraft.
A physical mixture axis is still relevant in the default 737: FSX can use mixture commands as jet fuel-control commands. If both engines start and then die, check whether that axis is forcing the start levers back towards cut-off.
Why does the engine quit during take-off?
An engine that idles correctly but stops as power is applied has a fuel-delivery, mixture, controller or simulated-failure problem rather than a starter problem.
- Watch the cockpit controls while advancing the throttle. A bad or duplicate assignment may move the mixture, propeller or condition lever at the same time.
- Check the tank actually feeding the engine, along with any crossfeed valves, fuel pumps and selectors modelled by the aircraft.
- Adjust piston mixture for airport elevation. An excessively rich or lean setting can produce poor power and may stop the engine.
- Consider carburettor icing after extended low-power operation where the aircraft and conditions support it.
- Clear scheduled FSX failures and inspect any separate add-on maintenance, wear or damage system.
It does nothing or it didn't work: how do I isolate the fault?
A controlled default-aircraft test separates an FSX-wide input problem from a saved-state or aircraft-specific fault.
Searchers describe the same result as Polish nadal nie działa meaning “still doesn’t work” or to nie to meaning “that isn’t the cause”, German geht nicht, Slovak stále nič—often typed stale nic—Japanese かかりません, and Russian все равно не запускает. In each case, the useful next step is the same comparison:
- Close FSX and disconnect external controllers. This prevents an axis from changing the cockpit immediately after the flight loads.
- Create a new flight. Use the default Cessna 172 at a low-elevation airport, add fuel and disable active failures. Do not load the situation that was failing.
- Press Ctrl+E once. If the engine starts and remains at idle, FSX’s basic engine simulation is working.
- Reconnect controllers one at a time. When the fault returns, inspect that device for duplicate throttle, mixture, propeller, condition-lever, magneto or starter assignments.
- Test the original aircraft last. If only that aircraft fails, follow its checklist and check its own saved panel state, interlocks and maintenance options.
- Restore the automatic-start binding if the default aircraft still fails. Recheck fuel and failures before considering configuration-file changes or reinstallation.
Can a saved flight prevent the engines from starting?
A saved flight can reload mixture, magnetos, fuel selectors, engine selection and other controls in an unfavourable state, while some add-ons save extra aircraft state separately.
Starting a genuinely new flight is therefore a better diagnostic test than repeatedly loading the same situation. See our explanation of how saved aircraft states affect later FSX starts if every new session inherits an unexpected cold-and-dark or fuel-cut-off condition.
Reinstallation should remain the last resort. It rarely fixes an empty selected tank, a mixture command held at cut-off, a changed binding or an add-on that requires its own start logic.
Does this FSX advice apply to X-Plane?
No—the fault categories are similar, but FSX commands, menu locations, saved states and default-aircraft procedures should not be copied directly into X-Plane.
If an X-Plane engine is not starting, check its fuel, mixture or condition lever, ignition, starter and controller assignments, then test a stock aircraft without third-party plugins or hardware inputs. If that stock aircraft starts, the problem lies with the original aircraft, plugin or saved configuration; Ctrl+E and the default FSX 737 procedure are not reliable X-Plane instructions.