Start a Cessna 172 from cold and dark using the correct fuel-injected or carburetted procedure, with practical fixes for common sim faults.
To start a Cessna 172 from cold and dark in a flight simulator, set the parking brake, select BOTH tanks, switch off avionics, turn on the master and beacon, prime for the fitted engine, crack the throttle, engage the starter, then check oil pressure before switching on the avionics.
The basic logic is similar in Microsoft Flight Simulator, FSX, X-Plane and Prepar3D, but the priming method depends on which Cessna 172 variant the simulator models. Identify the engine before following a checklist; using a carburetted procedure on a fuel-injected 172 is a common reason it will not start.
Is the simulated Cessna 172 fuel-injected or carburetted?
Most default 172SP models are fuel-injected, while many older Cessna 172 variants have a carburettor and manual primer.
| Engine type | Typical cockpit clues | Cold-start method |
|---|---|---|
| Fuel-injected 172R, 172S or 172SP | Electric fuel-pump switch; no manual primer | Prime with the auxiliary pump and mixture control |
| Older carburetted C172 | Manual primer and carburettor-heat control | Use the primer as required; do not copy the injected-engine sequence |
Add-ons can model different engines under similar-looking panels, so the aircraft's own checklist takes priority over the registration, livery or simulator name.
How do I start a fuel-injected Cessna 172?
This is the normal cold-and-dark method for a simulated 172S or 172SP, although switch labels and priming behaviour vary slightly between aircraft.
- Secure the aircraft. Set the parking brake, place the fuel selector on BOTH and confirm that the fuel shut-off control is fully on.
- Prepare the electrical system. Leave the avionics buses and unnecessary lights off. Turn on both sides of the master switch, then switch on the beacon.
- Set the engine controls. Put the mixture at idle cut-off and open the throttle by roughly a quarter of an inch.
- Prime the engine. Turn on the auxiliary fuel pump, move the mixture to full rich only until fuel flow is indicated, return it to idle cut-off, then switch the pump off. Follow any model-specific timed priming instruction instead if one is supplied.
- Engage the starter. Confirm the propeller area is clear, turn the ignition to START and move the mixture smoothly to full rich when the engine fires.
- Release the ignition. Let the key return to BOTH and set approximately 900–1,000 RPM rather than allowing the engine to race.
- Check the engine. Confirm that oil pressure rises, the alternator is charging and no low-voltage warning remains. Shut down if the simulated oil pressure does not respond as the aircraft checklist requires.
- Bring the avionics online. Switch on the avionics buses only after the engine is stable, then configure radios, navigation equipment and lighting.
For the default aircraft, our control-by-control MSFS 2024 Cessna 172 startup covers the simulator-specific sequence and cockpit controls.
How do I start a carburetted Cessna 172?
A carburetted C172 normally uses its manual primer rather than an electric fuel-pump priming sequence.
- Set fuel and controls. Select BOTH tanks, set the mixture to full rich and confirm carburettor heat is cold.
- Switch on essential electrics. Turn on the master and beacon while leaving the avionics off.
- Prime as required. Use the number of primer strokes specified by that aircraft's checklist and temperature conditions, then push and lock the primer. A warm engine may need no prime.
- Crack the throttle. Open it slightly, clear the propeller area and turn the ignition to START.
- Stabilise the engine. Release the key to BOTH when it starts, adjust to a sensible idle and check oil pressure and electrical indications.
Do not keep adding primer after every failed attempt. Overpriming can flood the engine, particularly when an add-on models fuel and spark-plug behaviour in depth. A complete Cessna 172 simulator checklist from preflight through shutdown helps keep the start sequence in the correct order.
Why won't the Cessna 172 start?
Most simulated Cessna 172 starting failures come from missing fuel, incorrect mixture, insufficient priming, a depleted battery or a hardware binding that overrides the cockpit control.
| Symptom | Likely cause and fix |
|---|---|
| Starter does nothing | Check the battery side of the master, battery charge, ignition assignment and starter control. Repeated long attempts may have depleted a battery modelled by the add-on. |
| Engine cranks but never fires | Confirm BOTH tanks, fuel shut-off on, correct priming method, ignition active and usable fuel aboard. Move a physical mixture axis through its range to clear any hidden override. |
| Engine fires and immediately dies | On an injected engine, move the mixture to rich as it catches. Also check that the throttle is cracked open and another controller is not pulling the mixture back to cut-off. |
| Engine is flooded | Follow the aircraft's flooded-start checklist. A common injected-engine method uses mixture at idle cut-off, pump off and throttle open while cranking, followed by prompt throttle and mixture adjustment when it fires. |
| Engine runs but avionics remain dark | Turn on the separate avionics-bus switches after start and check for a tripped breaker or failed electrical system. |
Saved flights can preserve an unexpected fuel shut-off, failed battery or stale switch state. Assistance settings and duplicate throttle, mixture or magneto assignments can also move a control back immediately after you click it. For systematic diagnosis, use our Cessna 172 no-start fault checks.
Can I use automatic engine start instead?
Automatic start is acceptable when the aim is to begin flying quickly, but it bypasses much of the cold-and-dark procedure and may conceal a faulty control binding. It is also a useful diagnostic: if automatic start works but the manual procedure does not, the aircraft probably has fuel and battery power, leaving switch order, priming or hardware assignments as the likely cause.