OK so here goes, my 1997 Blazer 4x4 four door with 251,000 miles will turn over but will not fire up on a intermittent bases, mostly on colder mornings around 50-55 deg F. No trouble firing when the temps are warmer outside and when it does fire up it runs smooth and I don't see a check engine light on either. I had the battery load tested and that look OK. One morning when it didn't start I did sprayed a good amount of starting fluid in the intake and still had no fire. The mechanic said since it's fuel injection that wouldn't work, but it seemed to last time when my fuel pump was going bad!?

So next I figured I'd just take it in so see what the local repair garage could find since I didn't have the time right now. Of course it started for them but they did put a pressure gauge on the the fuel line and said that the pressure came up rather slowly and that probably indicates a fuel pump that's going bad. So I had the fuel pump replaced along with both the electrical connectors that hook to it as I've read that one of those are prone to arching and overheating issues. About 2 years ago I had a fuel pump go and at the time I replaced the plugs, plug wires, cap and rotor and fuel filter also.

Everthing seemed fine over the weekend, but it was a warmer weekend, then this morning no fire up and temps were around 50 deg. F. So what should I try next? I'd like to look for a spark or lack there of but since it's an interminttent problem it's tough to reproduce and usually only occurs early in the morining as I'm heading to work. As the temps drop this fall I'm sure it'll be more repeatable problem but I rather get a handle on it now.

 

Just in case anyone has a similar problem it ended up being the coil/transformer.

At one point when I had the truck running I was reving the engine from under the hood and could heard what sounded like a repeated large static discharge. I just happen to see a spark jump from the coil to the coil wire or vice versa. So I would guess the insulation on the coil had broken down and was causing the intermittent starting issue due to a weak spark.

 

Thanks, I will check this on mine tonight hopefully!!