Hi sounds like the cold has killed your batterys but first check your connections,and grounds from the batterys, do you get a click when you turn the key, do the lights dim??? have you tryed a jump start from another truck?? 

re plugging it in that will help cranking by warming it up (thins the oil) but the batterys still need to be good!!  

Post over here... http://www.powerstrokeforum.com/

or here... http://www.oilburners.net/forums/forumdisplay.php?f=10

If the truck will crank and still not start. It's probably a couple of bad glow plugs.  And usually when the glow plugs go bad, so does the control module.

This happened to my 2000 7.3L during the Winter Olympics here in 2002. I was working at the downhill and could not get my truck to start after being parked in the parking lot. It would start every morning in the garage at 40* but refused to start when sitting in 20* open parking lot.  Try a little starter fluid (ether) sprayed into your air intac   A little goes a long way, just a 2-3 second spray. and then try to start. If its just one or two glow plugs this will usually be enough to get it running.

If you've got 4-5 glow plugs bad, then you are probably in for a tow.  Have them replace all 8 while they are are replacing the bad ones. Once they have the valve covers off, it's not very expensive to do all eight vs just 2-3.

If the engine won't crank, take a serious look at your batteries. My original Ford batteries never last more than 36 months. They will run fine today and be dead tomorrow, not a lot of advance notice they are going dead.

I run about 85,000 to 90,000 miles per truck before I sell them, Usually every 3 years. I've never changed out a cam sensor. But maybe I've been lucky.

The 7.3L Powerstroke needs to attaina certain rpm during cranking or it won't start. Couple that with 6-7 years batteries and you can have "issues". If the cranking rpm is border line, and your batteries are borderline, you will not have enough electrical reserve to power the injector circuit.

Also as others mentioned, you could also have an issue with either 1) one or more glowplugs have failed, and 2) the glow plug relay isn't functioning. Either of these is a common "no start cold" problem.

I would check 3 things.

1) load test batteries as individually, if one tests bad, replace both.

2) Have a tech check to see if the glow plug relay is working.

and if it is,

3) have a tech test the glow plugs, individually. if one or two are bad, replace them all. The are about $10 each for the parts.

I too am "religious about maintenance."  I replace the batteries at 3 years.

I have a good friend that is also "religious about maintenance."  He changes his oil at 3K, services all the other fluids on schedule, regularly checks the air in his tires AND he refuses to replace his battery until it causes him to be stuck somewhere . . . I have never understood his logic.  How much money can he be saving by waiting until he gets stranded?

Oh well . . . a good friend he is anyway!

Roll on

I'm not sure I appreciate the judgemental tone in which the last post was made. Had you read my original post fully and not been busy judging me, you would have seen that I had the batteries tested by a reputable technician who did not want to replace them because they were not even marginal. Why would he not sell me batteries when he was told to replace them if they were even questionable? Any idiot knows that if batteries last 3-4 years, you have more than gotten your money out of them.

This is not a question of me being cheap or stupid. My oil is changed every 3 months or every 3K, whichever comes first and is replaced with the proper weight oil. As the truck is 6 years old with only 50K miles, I've changed the oil much more frequently than recommended.

I've been driving for over 20 years and been left to sit very infrequently because I maintain my vehicles- not that I should have to quantify myself to your selfrighteous judgement. I can only hope it never happens to you! I thought this was a forum to help and educate people, not make them feel inferior.

Oh, by the way... The truck has been running fine since we realized the fuel had gelled and we corrected the problem!

Don't get excited by the tone of a post. Ignore it should it not be helpful.

We also have a f-250ps diesel. We plug her in when it gets really cold but mostly we do what another poster suggested,turn the key, wait a bit, then do it again. Sometimes three times in a row. It usually starts right up.

Congrats on getting your truck running again...

out of curiosity are you running BioDiesel?

If so, what percent?

As a side note...Gee...I'm glad I did NOT tell you to get a GMC Duramax...