What will not fire up?

My question posted before I could finish. Anyway, Ive got a York furnace model #p2mpd12n06401a, when I turn it on the exhaust blower comes on but no flame, the igniter glows like it should. The diagnostic light blinks once indicating "lockout-check furnace". Any help would be great

If the ignitor glows then it must not be getting gas, either bad gas valve or no power to the valve. Do you hear the gas valve click to open, or gas going in?

It is not getting gas, I hear some clicks, not from the gas valve. I was messing with it for about 1/2 hour and it lit up once early on, I hadn't done anything yet so I don't know why it fired that once, but I have been unable to do it again

Do you have a regulator in the gas line?

Yes, I believe there is a regulator. I'm not at the house right now, so I'm relying on my photographic memory.

Sometime if gas company messes with the line outside, or if the regulator goes bad there may not be enough gas to light.

I'll try to purge the line, and check voltage at the valve. Thanks for your input. I'm heading back over there to try again

Just thought I would add my experience to this list-

I had the same problem:
1. Exhaust fan turns on
2. Glow plug lights up
3. Gas clicks on
4. Wait

Sometimes it would catch at the last second as the glow plug started to turn off, sometimes it would just stop the gas and not light at all.

What I did to fix it was reposition the glow plug so it is about millimeter away from where the manifold and leaning toward the first gas outlet by about 2 degrees. Not so much that it is in directly in front of the outlet though. I think that would probably be too much heat. Now it lights up immediately. I'm not sure if the tilt is necessary, but I figured it couldn't hurt.

At the end of spring last year I had replaced the blower motor. I think I may have jostled the glow plug a little when I did that.

Hope that helps someone in the future.