This forum has been a wonderful place for advice and troubleshooting on my 240's. My 1992 has an issue that neither I nor any mechanic I've gone to have been able to figure out, and I've not yet seen it addressed anywhere. She won't start when the weather is mild and especially if it is damp out. If the temp outside is under 35 or so, or above 65, there are no problems. But anywhere in between, it takes forever to get her going and then she runs rough for the first 10 minutes or so. I've recently replaced the MAF and fuel pressure regulator.

 

You need a new Coolant Temperature Sensor and a new mechanic.

 

The coolant temp sensor has also been replaced -- but I'm curious as to why that would make a difference only when the weather is cool? Keeping my 240's on the road continues to be a learning experience It is fine when it is cold outside, or hot, but not in between.

 

The CTS sends a signal to the ECU determining how much fuel is needed, more when cold, less when already warm. The faulty sensor can be out of range on either side signaling who knows what. Hard cold starts are a classic sign of a bad CTS. If you replaced it with an off brand, it may still be bad. These days we see a lot of substandard parts on the aftermarket: people replace them and assume a new part is good which isn't necessarily so.