Hello. I have been searching for discussions about this problem for a week, but I haven’t seen exactly what I’m looking for so I just decided to make an account and create a thread myself.

So, I use an ‘03 Blazer for my mail route. For the first couple months, I had absolutely no problem starting it up. A couple weeks ago, when the air temp finally became consistently warm, I found out that the car will not start up after sitting for a while. It will start early in the morning, but once the air temp warms up, it cranks, but it simply will not start. And it will be like that until the next morning. I’ve never experienced anything like that. Last Saturday, I drove it to work at 630 am (that’s never a problem), but it wouldn’t start up at 915 when I got my mail loaded. I tried everything. I turned the key to electric repeatedly. I even tried shooting ether into it. Nothing works. Just have to wait til morning. I’ve taken it to a mechanic and he hasn’t been able to fix it yet.

Any ideas on what could be causing this? Also, the motor runs perfectly fine. It just will not start unless the temperature outside is cool.

 

Any help would be greatly appreciated. I have to work on Saturday and I’m desperate to figure this out before then.

 

Thanks for all the suggestions. Means a lot

 

Maybe a fuel pump going bad? I have had a couple fuel pumps in the past get warm and not want to start for a while. Also have had issues with the fuel pump relay getting old and doing something similar.

 

Fuel pump is fine. Motor’s getting fuel and the battery’s good. The guys at the shop said it could be the anti-theft system, so I guess we’re gonna try that.

 

The security system for the most part is easy to diagnose; turn the key to the run position and look at the "security" light. If it blinks on and off you need to do a re-set. if it stays on or goes off after 5 to 10 seconds its most likely not the security system. Do you have a remote start? In my case my remote start bypass interfered with my ignition security code and would give me a no start, (again blinking security light). I remedied mine by cutting the yellow wire from the key switch and taped off the ends. You can look up passlock security bypass and get the instructions. The security system will cut off the fuel pump and you wont get fuel. If what you say is true that you ARE getting fuel, you may want to check your fuel pressure, it needs to be 60psi plus or minus. Low pressure could be an indication of fuel regulator, or if lucky, fuel filter. Either instance will give you problems. Good luck.

 

its getting fuel because it’ll start literally every morning. When the temperature warms up during the day, all the sudden that security light starts blinking and won’t let it start. It never happened during the spring when the weather was cool at all times.

 

Problem is I’ve tried leaving the key on for 10 minutes like they’ve said to do on YouTube videos, and that hasn’t worked. Idk what the deal is. Like I said, it only happens when the temperature warms up during the day.

 

Well.. If the security light flashes and you do the 10 minute reset (and wait 10 seconds in the off position before starting) and it doesnt work then you have to go thru 2 more reset cycles and it should work. if you have tried that and still no start then its experiment time. If you havent taken it to the mechanic yet, next time it happens try disconnecting the battery for a few minutes and see if it re-sets something and starts. What you are describing is not what typically happens when the security system kicks in, it's supposed to shut off the fuel pump and you dont have any fuel delivery, thats why I suggest low fuel pressure. OR, if your BCM is acting up or other control module you could get a no start situation. Thats why I suggest disconnecting the battery and see if it re-sets something. Do you have a remote start on the vehicle? Does that work? If so try using Just that and see what happens. Good luck.

 

No I don’t have remote start. I’ve taken it to a mechanic and they think it has something to do with the security system, so we’re gonna take it to a dealership and see what they can do. I can try to disconnect the battery and see if that works, but I’m not sure it will. I’ve got a feeling that the whole passlock system is junked after reading up on stuff. I mean, what else could it be if the passlock system only kicks in when he temp warms up? And it’s consistent. I picked it up from the mechanic’s shop today at 8:30. Started up fine. Started fine at 9:30. Went out at around 10:30, and the security light was blinking - wouldn’t start.