Vehicle: 2015 Mitsubishi Outlander SE, Engine: 3.0L V6, Mileage: ~120,000 km

Issue:
- Long crank and stumble on start after the vehicle has been sitting (crank crank crank crank crank crank stumble stumble stumble start)
- It's been about a year and now seems to be getting worse. Before it would occur intermittently, now every morning it's happening.

Symptoms:
- Engine cranks strongly (normal crank speed).
- Crank duration can be 6–10 seconds before firing. Smells a tad like fuel after.
- When it catches (95% of the time), it stumbles/rough idles for a few seconds.
- After a few seconds, idle smooths out completely.
- Vehicle drives perfectly once running.
- Acceleration is normal.
No hesitation under load.
Warm restarts (after 5–10 minutes) are smooth and immediate.
Turning ignition ON/OFF multiple times before cranking (to build fuel pressure) doesn't seem to help.

Occasionally:
- Instance of crank/no-start on first attempt.
- On second attempt, pressing accelerator (clear flood mode) allows it to start.
- Using Scan Tool - No engine codes present.

Sit time:
10 minutes → starts normally.
1–2 hours → may long crank and stumble.
Overnight → most likely to long crank and stumble.
Behavior inconsistent day to day.

Work done to try and resolve:
- Battery tests good (1 year old).
- Alternator tests good.
- Timing belt replaced.
- Spark plugs replaced.
- Throttle body previously cleaned (seemed to help a bit about a year ago).
- Software update applied.
- Crankshaft position sensor replaced (OEM Mitsubishi part).
- Issue persists after crank sensor replacement.


What to check next? Dealership suggests it could be injector leak-down while sitting?
At a loss and want to figure it out, I really like my Outlander and want to fix it but don't want to continue chasing randomly.
Any experience or assistance would be greatly appreciated. Thanks Mitsu community!

 

injector ou injectors leaking is a good idea looks like the engine is flooding , try to start it next time with the pedal to the floor ... you wont damage the engine as long as you let go the pedal once started

 

Thanks for the suggestion. I have tried clear-flood (pedal to the floor while cranking), and when it is struggling to start/stumbling it does get the engine to catch/start.
I've been also trying to put key on for 10 seconds, key off, and repeat several times and it seems to be helping. If I leave the car for longer than 2-3 hours and try to start it - it will long crank and stumble again.
Any ideas what to test next?