1999 Blazer cranks but won't start when cold (about 30* F or less). Although the fuel pump is newer (less than 2 yrs & it is a Delphi), I have checked the fuel pressure and leak down. Fuel pressure is 64 and after 10 min leak down it was 59. If I roll it into the garage and warm it up, it will start. Once it has been started, it continues to restart. Below is a list of recent parts replaced in the last month:

Cat Conv & exhaust
Intake manifold gasket
Spider injector
Coolant temp sensor
Thermostat
Cap, rotor, plugs & wires
Battery
Coil (about 1 year ago)
Starter (about 6 months ago)
Swapped MAF, IAT and ignition module from a 99 Jimmy & same result/problem.

The Blazer has remote start that was disconnected and still had the problem. We also have checked for vacuum leaks and didn't find any. We found 155 psi of compression at each cylinder. Live data checked with MAC scan tool. There is a code but it's evap emissions.

Please let me know if you have any suggestions.

 

Put the coil/ignition module assembly in the freezer in attempt to recreate the failure with the blazer still warm in the garage. It started up. Put the crank position sender in the freezer & reinstalled...still started. Put the ECU in the freezer & called it a night. I will reinstall tomorrow and post results.

 

Pulled the ECU out of the freezer and reinstalled. The Blazer started fine. Welcome any advice or insight.

 

While it's cranking, and not starting, have an assistant spray a half second shot of carb cleaner into the throttle body. Post the results. Do NOT use starting fluid, (ether). If the engine backfires, or there is a stray spark, you'll have an instant flash fire in your face.

 

Captain Hook- sorry it took me a while to try this. While cranking, we sprayed a half second shot of carb cleaner and the motor just kept cranking/no start. It didn't even make an attempt to start. Today's static temp was about 18* F. I did notice the security light blinking on the dash Which makes me suspicious of a Passlock issue. But this still doesn't make sense to me since the Blazer will start when the temp is above freezing. Also, after I added the RC lift and 31" tires, I had the PCM flashed to account for the larger tires so the speedometer would be correct. While doing this, I also had the programmer delete the security feature so that the additional keys I had cut would work. This was done about 2 years ago. The keys have worked although we primarily use the factory key. I have tried both keys during this ordeal and they both work when warm but once the temp drops below freezing, it won't start. We also checked the fuel pressure again and it read 62 PSI.
Thx for your help.

 

If the spray had no effect, the problem will most likely be ignition related. The flashing Passlock light is a problem, but Passlock only disables the fuel injectors, not the ignition. Check for spark at the ignition coil while cranking. It must be able to jump a half inch gap, and produce a blue, not orange, spark. Post your results.

FYI: By removing the crankshaft position sensor, the PCM now requires the relearn to be performed with a capable, (high dollar) scan tool. The engine will still start and run, but ignition and injector timing will not be correct.