Firstly, I have read all of the 6.2 no start/troubleshooting in the member's area as well as the glow plug troubleshooting article. I have also read through dozens of other similar posts.

91 6.2L K5 Blazer. 225K miles. Won't start.

Changed fuel filter. Fuel seeps from injector line when loosened.
Glow plugs are all getting voltage.
Tested glow plug controller per article. Seems OK.
Motor turns over fine, and puffs of white smoke are emitted from tailpipe, which leads me to believe that the motor is cycling fuel through it.

It's hot here in NW Florida (98 deg. F today). Had block heater plugged in as well (for extra heat to aid in starting, not sure if it really helps). So I would think even if glow plugs weren't working it should still start. Have a charger/starter hooked to one battery and I have my other truck jumper cabled to the other battery for plenty of starting juice. Turn-over does well, and I'm sure starting RPM's are fine.

Unhooked glow plugs and tried a little ether.. No start, of course, I'm doing this by myself, so It's spray and then run over and turn the ignition switch.

This all happened "overnight" so to speak. I was letting a buddy drive the truck and one day he came by the shop (work) and turned it off. 30 mins later he tried to leave and it wouldn't start. I changed the fuel filter and bled the lines right then. We also tried pouring a little diesel into the intake. Eventually, this got it started. He was able to make it around for a few trips (100 miles) and then when he got back home and turned it off overnight it wouldn't crank again. He claims that it was running just fine while it was running. He said he was able to crank it again by putting a little diesel into the intake. He also said that he could turn it off somewhere for a few minutes and it would crank back up, it just wouldn't crank after it sat all night. So of course, I'm assuming glow plugs.

Now, it's been a month since I dragged it back to my house to work on it, and this morning, I finally found time to do some troubleshooting. I can't get it to crank at all now. Not with diesel in the intake or Ether.

I'm thinking about going ahead and replacing the glow plug controller and all glow plugs, just so that I can eliminate that. I'm sure this would be at least 100 bucks though, and I hate replacing good parts, just to find out later they were fine.

I'm also thinking about dragging it to shop, but it's so darn hard to find a good diesel mechanic that really knows what he's doing.

Any suggestions (I will try the ether again later, when I have someone to help)?