I have been looking around this forum for a little bit and there seems to be a wealth of knowledge here so I joined the site. I hope someone has a solution for me. My '99 Jimmy failed to start after sitting for a couple days. Local temp has been in the 20's and dips into the teens overnight. Here is what I have done/figured out so far

-new plugs
-new cap
-new crank sensor
-ignition module is good
-coil is good
-have spark to plugs
-fuel pressure is 60 psi
-old plugs had fuel on them when I pulled them so fuel is getting to cylinders

The engine missed a bit the last week or so. Under heavy load, it would miss quite a bit and flash the CEL. I figured the plugs just needed replaced. It also would consistanly hesitate a little around 2k rpm. I noticed the thread from rifleman308 about checking for AC voltage from the alternator and a bad ground to splice pack sp423 could these contribute to this?

 

did you notice the pressure dropping fast?

 

So it Cranks but just wont kick over...missfires can be a pain to figure out...but there are only a couple things that could cause them..
A partialy clogged or restricted injector
vac leak
sticking valves due to carbon build up...(which is a big concern in cold weather)
Do you know what Codes you have stored????? im sure youll have a p0300 missfire code..

 

I got it running. It appears it was a combination of needing a tune-up and possibly a bad intake air temp sensor. After I got it running I went and had the codes read. I had P0300, P0440, and P0108. I cleared the codes and drove around about 25 miles with no codes. It runs a lot smoother however, it is still kind of sluggish from about 1800rpm to about 3000rpm. The temp is in the single digit range today. We will see if the starting issue is solved. The sp423 check will have to wait for now.

 

Glad to see you got it up and running.