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Key turns but doesn't turn the engine

2010 f150; intermittently the key turns fully without turning the engine on. Still under warrenty, been to shop twice, cant find anything wrong and service people have no clue. new battery, no codes. Occurs usually after the truck has run never when sat idle for a period. Start after a while can be 1 min to 2h.
Any clu?

There’s many possible failure modes that can cause this symptom. Need to narrow it down. Does it crank? You know, the “rrrr” … “rrrr” sound that the starter motor is turning the engine over? Does it do that every time?

no crank. just some audible clicks, it does the the same every time but unpredictable maybe one a week or 4 a day. could never duplicate in the shop (of course)

Most likely would be a bad battery, corroded battery connections, worn starter motor solenoid contacts. Could be the ignition key and neutral or clutch safety switch too. If this car has ever had extensive work done to it, or been in a wreck, or is rusted, bad grounds can cause this symptom too. First thing I’d do, ask your mechanic to measure the voltage at both terminal of the starter motor (thick wire, and thin wire, to the case) during attempted cranking. If the thick wire is less than 10 volts, suspect a run-down battery or battery connections. If the thin wire is less than 10 volts, suspect a problem in the ignition switch or safety switch. If both voltages are above 10 volts, suspect a bad starter or starter solenoid contacts. Best of luck.

fairly new, no work done , new battery tested fine.

The key doesn’t turn the engine, the starter does. Since you have a new battery, surely the cables are ok, and the solenoid is clicking, I would guess the problem is the starter.

I had a 4.6 in a Crown Vic that did that. A new starter cured it…Make sure the starters heat shields are in place if it has one…On a vic, the exhaust pipe runs close to the starter which can cause hot-start problems…

I have kinda the same problem my wife drove my 2001 ford escape to Walmart lost key had another in car it started got home she went to leave and nothing turned key but nothing no click nothing I get home she tells me what’s going on so I get in car and worked fine 2hours later I go to leave and nothing same problem ?

I’d say bad starter or bad connection to starter.

cant reproduce it in the shop. been in ford dealer shop for last 2 wks. says the starter is fine connection fine.
i was going to call ford customer service a call tomorrow.
let you all know when (?) i get it figured out.
thanks for the inputs.

The starter may be “fine” intermittently.

@MG McAnick is correct. Starters can be very intermittent. Junk gets on the starter motor brushes and sometimes you can give it a whack and the car will start.

Yep, I still bet it is the starter.