Engine Stalling on Hot Days; HOT FUEL?

[TeDeEye]

I have a 2004 Golf TDI PD with a turbo and clutch upgrade done two summers ago, Aug. 2019.

Starting around late-summer 2020 and through this summer when the outdoor temp is above say 75Fdeg the engine will spontaneously shut off, and won't start again until I wait a bit allowing the engine to cool down (how long depends on how hot it is).

The engine coolant temp was fine, 90Cdeg - I replaced the thermostat.
Often I'd get a code for intermittent Cam Position Sensor signal - I replaced the CPS. I'm guessing due to the engine suddenly stopping.

I noticed the fuel filter was very hot - I replaced the lift pump, back-flushed the fuel cooler, and replaced and then reversed the Thermostatic Tee. I removed the lift pump well cover under the back seat after noticing how hot the fuel lines were. The stalling happened less, but on HOT days it was still a nightmare.
And now I'm an expert on instantly shifting to neutral and rolling to a stop.

Finally, one particularly hot summer day after stalling on the highway with my son, I decided to take a frozen gel pack from a cooler and place it on the fuel lines in the well. The engine started and ran all the way to my destination. ***

The only other thing I noticed was that the fuel lines (supply and return) in the engine bay run right over the 2" aluminum pipe from the intercooler; that pipe can get very hot. I left a gap between the pipe and the hoses, but stalling still occurred.
Recently I checked the lower intercooler pipe for oil. There was very little.

WHAT IS CAUSING THIS?!

Any suggestions appreciated.
I would like to resolve before May...

P.S. Will reversing the Thermostatic-Tee cause any issues, besides extending the engine warm-up time in cold weather?
Any thoughts on the Kerma widget? - https://kermatdi.com/i-443-kerma-widget-mk4-bhw.html

 

[Mongler98]

There really is no reason it should be getting that hot. lets find out why
the fuel lines being close to a heat source might not be helping things but i dont know why you have such high fuel temps other than a worn IP but you said you replace the lift pump but not the IP... i would start to look into the IP as being the issue. is fuel actually making a nice flow back to the tank?
take the return line off and have it go into a cup and run it. do the same back at the tank. maybe not enough fuel is going though the fuel line. my hunch would say that its the check valve. at the tank is some how not letting enough fuel though.

you could run a 1 gallon fuel loop and see if the IP is the cause. You did not mention you changed the filter...

My best guess is its a flow issue

 

[TeDeEye]

There really is no reason it should be getting that hot. lets find out why
the fuel lines being close to a heat source might not be helping things but i dont know why you have such high fuel temps other than a worn IP but you said you replace the lift pump but not the IP... i would start to look into the IP as being the issue. is fuel actually making a nice flow back to the tank?
take the return line off and have it go into a cup and run it. do the same back at the tank. maybe not enough fuel is going though the fuel line. my hunch would say that its the check valve. at the tank is some how not letting enough fuel though.

you could run a 1 gallon fuel loop and see if the IP is the cause. You did not mention you changed the filter...

My best guess is its a flow issue

Yes, I did change the fuel filter.
I'll check the return flow and the IP. Thank you!

 

[befarrer]

For how easy it is, change the crank position sensor. I've had those sensors go bad on different vehicles, and the engine just shuts off, no codes. They usually act up when they get hot. I can't see it being fuel, you have a PD engine, fuel flows through the head, so it will be at coolant temperature.

 

[zslnk]

[Deleted] Post written prior to befarrer replying with same content.
I'm not sure hot fuel is a problem here. It's normal. If it shuts off cleanly at speed without any drama or codes id say G28 (Crank) as first step.

 

[pruzink]

If you search "Kerma Widget" on here, you will find a device that replaces your 3 way fuel temperature regulator valve at your fuel filter. The Kerma Widget replaces it & returns all of the fuel being returned from the fuel rail to the tank all of the time. If you have ever done the "Diesel Purge" injector cleaning, you remove your fuel filter & replace it with a can of diesel purge. The fuel line supplying fuel from the in tank lift pump gets jumpered (a piece of snug flexible tubing is pushed into the line) to the return line that goes back to the tank. The fuel line that provides the suction to the tandem pump gets a piece of tubing to take a suction off of the can of diesel purge, and the return from the fuel rail returns into the can of diesel purge. Starting with a cold engine, the fuel rail return gets pretty hot quite fast. This is why I replaced my fuel filter thermostatic valve with the Kerma Widget; I figured that tis valve just needs to return al fuel to the tank 99% of the time so why not just do it 100% of the time. I agree with the previous posts that the most likely cause for your problem is your engine speed sensor. I had this sensor fail on my 2004 BEW Jetta & was having intermittent stalling after the car was warmed up (no codes either).