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Car won't start in cool (not cold) weather

My 98 Oldsmobile Achieva won’t start if the weather is below 40 degrees, not even cold! It will start later in the morning or in the afternoon. I have it in the shop now, but would like opinions on this, as my mechanic is not sure what is causing it.

“Won’t start” is rather vague. What, exactly, happens when it’s below 40 and you turn the key?

Oh, sorry…it turns over just fine and acts like it is going to start, but dies. Not the battery, I’m sure because it sounds normal, it just dies right away.

It’s probably not getting enough fuel to run rich enough when it’s too cold. Check timing too.

Thank you. Like I said, it’s in the shop right now, and these people are really good. They have always treated me right and been able to fix everything for about 20 years now. so hopefully they will be able to tell. It did it for the first time with them this morning, so should be easier for them to tell.

Is there any connection to damp weather?

Any check engine light on when it’s running? Have you tried a new coolant temp sensor?

No check engine light. No, I haven’t. I’m sure they will get to the bottom of it. He is replacing an ignition switch that was bad and he thinks it’s all related.

I doubt the engine would be cranking if the ignition switch was bad.

Actually, it is a new switch they just put in not long ago. The old one was bad because the car wouldn’t start at all. Now he thinks maybe the new part was bad. It happens. He mentioned something about the ignition lock or something.

If the engine cranks when you turn the key, what’s the problem? I hope you’re not paying more money to have them work on the ignition switch again.

No, they are not charging me any more. It cranks but immediately dies. One morning it was a little warmer than it had been, and after about 8 or 9 tries, it started. In the afternoon after it warms up (it’s been in the 80’s here) there is no problem starting it. It doesn’t seem to me like it would be that switch. I know this is an honest man, I have known him for 20 yrs and I know he will eventually get to the bottom of it, because he always does.

This same thing happens to my 98 v70 volvo. Cranks and runs fine if weather is over 50F. Below that, it will crank and start first time, but sputters out and dies almost immediately. I can sometimes get it running if I try about 10 times in cooler weather.
In afternoon will start right up. What is this?

Have them check for a faulty ignition module.

The ignition module functions in two modes. These are the start and run modes. When starting the engine, the ignition module goes into the start mode and allows full battery voltage the coil packs. This ensures there’s a hot enough spark to start the engine when it’s cold and fuel mixture is rich. Once the engine starts, and the ignition switch moves to the run position, the module goes into the run mode. The module then drops the voltage to the coil packs because the charging system starts putting out a higher voltage than the normal battery voltage. And if the voltage to the coil packs isn’t controlled it’ll eventually burn out the coil packs.

So it could be that the start mode of the ignition module is functioning, and the engine starts. But the run mode of the module has failed where the engine shuts off as soon as the ignition switch is allowed to move to the run position.