I have noticed that after driving 09 xk for awhile and park the car, when I get back in shortly after car will stall when trying restart engine. About the second or third time it wants to start to stall I give it gas like in the old carburator cars and it starts. Runs perfect after that. Any ideas?

 

Sounds like heat soak, but I haven't seen other reports of this. Probably worth taking it to someone with a diagnostic system that can read any codes that it's generating. I assume that no warnings are coming up on the dash.

 

I don't have the parts catalog in front of me, so can't say whether the fuel pump assembly is the same for the 4.2L x150 but even if it isn't literally the same pump, the fuel system is of a similar design.

On the 4.2L x100 there is a check valve in the pump assembly to prevent the fuel from draining back to the tank. If it fails then when the engine is warm it causes the fuel in the rail to boil, pushing the fuel back to the tank. The next time you try to start the car the pump has to move the fuel all the way from the tank to the fuel rail causing a long start.

If you just spin the starter and don't touch the throttle, does the car start?

The pump runs for a few seconds when you turn the key one, so another thing to try is to cycle the key on a few times to "pump up" the fuel system.

To diagnose it, you can use an OBD meter to read the fuel pressure. When the key comes on, you should see the pressure come up to about 55psi and hold there. If it falls off immediately then that check valve is most likely the culprit.

 

I had the same problem with my 08 XK, when the engine was hot and then the car was parked for 10-15 minutes, on restart it would start then immediately die. It would continue to do this until you caught it with the throttle and held the rpm’s up for a few seconds then all would be fine, it would idle correctly and drive just fine. Incidentally no check lights and, no codes were set.
The solution, for me anyway, I found by accident. I disconnected the battery for a few minutes to address an unrelated issue, and it never did it again. You might try it, easy to do and you never know…
Regards,
White Bear.

 

That kind of thing has happened to me now and then. Not often enough for me to start investigating. Figured it was the battery or something.

 

Interesting, I do wonder if it's the battery.

What is heat soak in this context, and what would it have to do with stalling?

 

Heat soak occurs after an engine is turned off and its cooling system isn't running. Heat begins to redistribute through the engine, and parts of it get hotter than they would in normal operation. If you try to restart it while it is in this state, it may not run properly - for example, fuel in the fuel lines may have temporarily vaporised, as cfulton said.

Engines are designed to reduce the effects of heat soak - heat shields and insulating gaskets, for example - and control systems are usually able to compensate. But sometimes these deteriorate over time, and then it becomes a problem.

 

Probably not.

Disconnecting the battery or deliberately performing a 'hard reset' loses learned ECM adaptations such as fuel trims.

On reconnecting these will start at default settings and gradually adapt again with driving.

Graham

 

It happened before I recently replaced the battery with AGM. Happened after so I dont think it has anything to do with the battery.