Hi I have a 01 Chevy blazer that won’t start when weather is below 40 I have changed ever senior on it could use some help thanks

 

Does it crank, but not start, or no crank?

If it does crank, is it a normal, strong crank, or weak and slow?

 

. Crank over good and strong it has no spark come out of coil when cold but good spark when it is warm out

 

That's strange. 40 isn't even that cold. Above freezing. Maybe a new coil, but I hate throwing money at something.

 

I have replaced distributor, cap and rotor, coil pickup, ignition coil, control module, crank shaft position sensor, plugs, fuel pump and a coolant temperature sensor. /computer I just don’t know what else to try

 

I know you think it's an ignition, issue, but replacing all those parts, should have fixed it if that's the case.

Have you checked your fuel pressure when it's not starting? That's the next thing I would check. Even if it's fine, you can at least rule it out, and move along with troubleshooting

 

I have no spark coming out of coil when cold but good spark when it’s warm out

 

Man talk about throwing parts at a problem, okay look you need to step back and think about this. Considering most parts that are electrical are not returnable why dont we do some checks/tests to narrow down the issue. Check battery? Check grounds, especially grounds. There are several to look at, I know one behind battery on backside of headlight area. Another goes to firewall, and you got one the drops down to engine block low on passenger side. Why? Because it’s temp related. Hot /cold metal contracts/expands and seems like a loose connection be first thing to check for and cost nothing but time to look.

Next would be some of the main connectors. Look at ones under hood first, passenger side on the main computer. Literally just unplug them (they are color coded and have notches to prevent plugging in wrong so basically fool proof). Look to see if they are clean, no corrosion or anything suspect. Again this cost you nothing but some time. Then look over the relay box under hood. A sticking relay in cold conditions could cause this so look them over. If its cold give a tap and then try to start. See if you can narrow this issue down. The cover is labeled so you can find the ones to look at.

There is no magic bullet and your issue is not that common but I think this can be resolved. It’s electrical and somewhat intermittent seeing only when cold. I wonder if when driving and you go into the cold when it was already warmed up does it just die?

 

Ok computer I dont think is problem just had that off and back on looked good and clean / you say there only three ground wire I will start there thanks for the tips we keep you up dated

 

The relay box you talk about is that the out side fuse box