I'm sure somebody on here has run into this issue and I'm hoping you can help me out. My 2001 F350, 7.3 won't start when it is cold or at altitude. By altitude I mean over 6000 ft. It starts fine in Phoenix but when I go up the mountain it just won't catch. I can hook a portable generator to the battery and after about an hour it will start, but then it blows black smoke for a few seconds and then runs fine. I replaced both batteries and the cam sensor, blindly hoping that was it, but it is obviously not it! I spent the week Turkey hunting and almost didn't make it home! Any help guys?!

Thanks, JO

 

Thread moved to the 7.3 forum

Good luck! You'll get the answers you need here.

Methinks there's some atmospheric pressure sensor somewhere, but I'm not a newfangled electronic diesel guy

 

Check the glow plug relay. It's probably a cold weather problem rather than altitude.

 

Do you get the black smoke when it's cold and you're not at a high altitude also? Your air filter is clean, right?

 

I second this. The glow plug relay is not the greatest.
Same thing happened to me as well.
Starts great at sea level and then once I got to Colorado on vacation one day the truck wouldn't start without jumping the terminals with a screwdriver.

 

how do you" jump the terminals "
It hasen`t happened to me but knowledge is great

Hanklin

 

Bridge the two large terminals with a screwdriver.

 

Sounds like your GPR. I live in altitude and it's not the thin air that's the problem with the hard starts. If it was cold out, your glowplugs are not properly heating the cylinders prior to starting. You just didn't realize you had a weak GPR in toasty Phoenix.

 

I HAVE THE EXACT SAME PROBLEM. And its not the cold. I live in Wisconsin, and it gets colder here than in Leadville Colorado, yet my truck has a hell of a time starting in Co. at 50 degrees. In Wi. I have no problem down below zero. New glow plugs and relay. Doesnt fix the problem. Leadville is 10,500 ft elevation, Green Bay is about 300 ft. elevation. I have been back and forth several times between the 2 and it is ALWAYS the same.

 

I'm thinking it is your glow plug relay, or the glow plugs themselves. If you have a way to get the codes pulled, try doing that, it should have something stored. I live at 7000ft elevation here in Flagstaff, and my truck will start in -10* weather without being plugged in NO PROBLEM. I've never heard of an altitude sensor for these trucks, but that doesn't mean it's not on there lol. Another great thing that helps ease with starting in the cold, is synthetic oil. That eliminated the "chugging" my truck did once it gets below 35* or so. There's my .02 cents.....