Hello JK gurus,
I have a 2007 JK 2 door sahara. I have a intermittent issue with the engine hesitating or bogging when the engine is a higher temps. Example would be a 30 min hwy run and while trying to take off from a stop the engine hesitate boggs or dips before it recovers and takes off. Seems like a lack of fuel. This only happens when engine is good and warm and is worse on hot days in stop and go traffic. When cold or just after starting there is no symptom. While turning and shitty clutch work it can stall out too. This very seldom. Any ideas on what to look at? Engine is high kms 300kms. Was thinking sparkplugs likely haven't been done in ages. Saw some video on crank position sensor was an easy fix and maybe the symptom displayed. NO codes on dash to speak off. I also found out I need to replace my fuel fill valve going into the tank. This was some recall for 2007. Tank spits like crazy when filled. Could this issue be related to fuel tank pressure or fuel system?

I know that's a lot to digest. Any suggestions would be appreciated.

 

Fuel getting too hot in the lines perhaps. Underhood and water temps on the JKs are horrendous. Mine is now down to run at 190F = 96C. 3.6 Engines usually run in the 220-230F =104-110C. Also a lower fuel pressure in thelines will cause the fuel to boil at a lower temperature. Your fuel pump maybe running a tad low given the 300k kms on it.

 

Temp related running issue makes me think of sensors.
Mainly the engine coolant temperature sensor.
and there is that ambient temp sensor on the front of the vehicle.
I recall reading that the 3.8 uses it to help calculate fueling or something along those lines.

That said, the engine coolant sensor is my first thought.
After that the MAP and the MAF.

 

I am actually mentioning real issues not sensors. IE if pressure was lower or somehow heat soak is getting to the fuel lines then the issues I mentioned may appear. Unless you are throwing codes then all sensors are probably ok.
Tank spitting is simply a terrible breather while filling issue and there was a recall but it has long expired for it. I just listen for the fuel coming up the spout and stop before the spill. Remember in 15 years time the new JLs will have the same issues.
J'Fishn- I don't believe the 3.8s had a Mass Airflow Sensor. Volumetric Eff was simply calculated by temp/MAP.

 

As mentioned, sounds like a fuel vapor issue.