I've actually found although not a great solution a solution I made a plug in switch set up that plugs between the sending unit and the plug on the wiring harness (so I could "unplug it from inside the cab without butchering my wiring harness to splice in) that seems to have completely ended problem without throwing the switch except in temps below 20. (I was having to unplug it below 50) Maybe the extra wiring changing the voltage going to the sending unit. I'm not sure but id still like to know what the actual issue is and solve it without the my current jerry rigging

 

Remove whatever youve done to work around the problem and fully restore the system. Unplug the fuel heater. Try again.

Long buried and forgotten, a faulty fuel heater usually surfaces during sudden cold snaps when outside ambient temps drop near or below 45°F or so. Thats when the self regulating 12vt fuel heater is supposed to start heating things up. Its either ON or OFF, its not variable heater element.
When they just wont die, they malfunction internally or short out externally, it will usually blow fuse(s) disabling GPR circuit, LPR circuit, WIF circuit, EGR circuit, just to name a few...
The fuel heaters rubber gromet used to protect the pigtail from being damaged, and/or the pigtail itself deteriorates (potential short) where it enters the fuel heater. Sometimes it will cause the WIF lamp, MIL, and STS lamps to flicker and/or fade on and off.

just a thought given your 60 degree notation at that time. I suspect it was cooler earlier so the fuel hadnt fully acclimated just yet maybe..



good luck..

 

I'll go ahead and change it since I've never been into that I just assumed since it wasn't gelling it wasn't the problem. But Just wondering if you could clarify are you meaning that it could cause gelling which is definitely not the issue or do you think it could be causing a voltage issue linked to my fast idle and advance timing not engaging. Works with it unplugged and new ac delco temp sending unit so it's somewhere in the voltage or whatever's reading it..

 

Although discussing a possible fuel heater malfunction, fuel gelling not a consideration here. Its purely an electrical (short) fault possibility..

 

Alright thanks man that sounds like the most likely culprit and it's a good cold morning for trouble shooting