Hello, I am in need of some help. I have a 1985 ford f250 that won't start. I've noticed the past couple days it's been getting harder and harder to start but today it's a lot colder than last week and it doesn't want to start. is it because of the cold? I let it sit in the on position for a few minutes to let the glow plugs cycle through and warm up but today it's not having it. any help would be much appreciated.