Last Tuesday it was a cool -26°C in Ontario, and in the morning I had a hard time starting the 850. It's a '95 10v 5 speed with 240,000kms.

The car was cranking well given the temperature, and it seemed to fire a few times but not enough to start it. After an extended bit of cranking it finally started, but ran quite rough. If I tried to give it a bit more gas it was resistant to that idea and would still run rough, but didn't want to rev up.

Plugs, wires, cap, and rotor were replaced in August. I'm not sure when the fuel filter was last replaced however. It starts, runs, and drives fine in any other temperature.

I've looked at other posts, but nothing that has my set of symptoms. Fuel pump relay? Fuel pump? Coil? Where should I begin?

 

check for vacuum leaks? specially if its cold?

 

fuel pump relay..

Remove it ( under the hood where the fuse box is, take out the 4 torx screws, its in there) keep it in the house at night, pop it back in tomorrow morning, if it starts up more smoothly, change that, and you should be good to go.

 

I will check for vacuum leaks when I have some time. After work I will remove and bring the relay inside for the night, and report my findings tomorrow. Thanks.

 

Sounds to me like maybe you fouled one or more plugs; that is, if it runs but never clears up?

Your battery may be on its last legs too; ck the voltage at battery terminals while cranking (ck when its cold so it take awhile to start..); shouldn't go below about 9 volts. If it does, battery is low, and/or time to replace.

 

After the relay spent the night inside, I reinstalled it this morning, and also did a voltage check on the battery.

It's about -16 here and the car started and ran fine. Voltages were about 12.5V before starting, about 12.3V in the II key position, and dropped to about 10.1-4V while cranking.

I was hoping for a much colder day for a good test. Is this conclusive?

 

yes,

your welcome

 

Given those results it seems your battery is fine and if it ran w/o missing then it was not fouled plugs either. Inclined to agree w/Matt01 at this point..

 

After work (3:30AM), it started nicely in about -15°C, BUT there was some misfiring. It only misfired at cold idle, and not at any other time. When it warmed up I didn't notice any more missing.

 

mine does the same thing when started cold, i have a feeling it will stop when i change the relay, the cars not getting the proper amount of gas for a short period of time. (relay is shot) For me its not really a misfire it just starts up rough.

Also in these cold temperatures dont keep your cars tank empty.
This morning it was -18, i put in my relay, it took my still about 3 tries to start it, but after getting in from work after about 9.5 hours it starts right up, it's only in the morning i have problems.