LM7 runs rich/dies in extreme cold

[Aaron Borman]

1999 Silverado 1500, 5.3 iron block (LM7)

Completely stock other than cat delete

I know it’s a bit much to ask an old truck to run in this kind of weather but I don’t have much choice unfortunately. Drive to work is mostly highway or gravel road driving. Every year when the cold snap hits (-40° range), my truck will, I assume, run rich (can smell fuel in exhaust and fuel consumption goes thru the roof on a 15min drive) and will eventually choke on itself and die, even while driving 80-100km/h. I have a winterfront on, have replaced MAF sensor, wondering what to try next. Truck runs perfect any other time.

[Sharpz]

A smoke inspection of your vacuum lines will rule those out.  Cleaning the Tb and Map sensor when you can can help.  Also if its been a while, go ahead and change your coolant sensor, being sure not to get any antifreeze on the connections. Using tape on the new parts connection until after it is in will help.