1996 7.3- intermittent hard start/no start

[Andy FitzGibbon]

Truck is a 96 7.3 with 5 speed. Just came back from dealer, where all four engine harnesses and both valve cover gaskets were replaced, oil was changed. I replaced fuel filter withing the last 500 miles and CPS about two weeks ago.
Dealer says they checked glow plugs and they were OK, but they have been seeming sort of weak to me. Sometimes I have to cycle the key twice to get it going in colder weather. I only drive it maybe 3-4 times during the winter, other than that it sits.
Every once in a while it just won't start. Example- started it at 8:00 Sunday morning, it was about 18 degrees out. It took a few tries, but it started fine. Block heater was not plugged in. Today, it was close to 50 during the warm part of the day and truck baked all day in the sun. I tried to start it at about 3pm, with no luck. Plugged it in and tried about once a half hour until it finally fired at around 6:30.
When I release the key after cranking it I get smoke from around where the head pipe is clamped to the turbo. This whole process has happend a couple times before. It seems like if I just let it sit for an hour or two it's fine.
Basically it feels like a carbureted gas engine that's flooding- can that happen on a diesel? Don't have a lot of experience with them. Is it an issue of the glow plugs being weak?
Thanks in advance,
Andy

[bigcountrysg]

For the block heater to work you need to have it plugged in for a minimum of 3 hours before starting. By the way it sounds it maybe the glowplugs or the glow plug controller not working properly. You can check the glow plug controller with a volt meter. Just turn the key on and check the posts on the glow plug controller for 12 volts.

[sldghamr]

i had the same problems years ago. ended up being that batteries were dead. didn't have enough juice to operate the glow plugs.

[Andy FitzGibbon]

Thanks for the replies. I knew that about the block heater but figured I'd mention it anyway. I didn't think that was what made it start. Every time this happens it seems like if you just let it sit for a while it will fire up.
The dealer replaced one battery as well, thought it was weird they didn't replace them as a pair but what do I know
I will check the glow plug system one of these days, as of now the problem is so intermittent that it's not too much of a hassle and would probably be hard to track down anyway.