HI, new member,
I didn't see, or couldn't find my problem. I have a 2003 express 1500 4.3L V6. Been sitting in freezing weather 4/5 days and won't start. It chugs over OK, but not fire, or slight stumble. I check spark from coil to distributor; good spark. I put in fuel antifreeze couple day ago. No go. I have heated engine at distributor and fuel lines at back of engine, then sprayed starter fluid in intake as close to engine as possible. Still no ignition, a little more stumbling, but no go on starting. Wondering what you gentlemen think could be the problem, OR I"m the problem. Any help appreciated from Kamiah, Idaho. Thanks

 

1 - is there spark at the plugs
2 - have you checked the fuel pressure? Does the fuel pump run when the ignition is turned on (you should be able to hear it)?
3 - a scan tool with live data capability may shed light on the problem if you have spark and fuel.

I will give an example, my 2002 2500 would not start when hot when it was 80'F or more out; the culprit was a bad coolant temperature sensor which believed it was -68'. This had the computer adjusting the timing and fuel in such a way it would not start.

Were I to guess it may be a cap and rotor issue, but it could also easily be fuel pump or regulator.