rough start no charge

[seth06f250]

im wondering what you found out with your truck. in the past 3 weeks mine has become hard to get started in the morning.. i went from no problems starting to the truck having to be cranked many many times. it starts and runs for about 2 sec and shuts off again. then i start the process over again untill the engine gets to above 90 degreese, then the truck may stay running but it is lopeing and puking out tons of black exhaust. once it gets over 100 degreese it all levels out and seems to run fine. the other day however once it did stay running it sounded like it was missing on a few cylindars untill it was warmed up.
also i have replaced the one of the batteries in it this past week, since i have killed it with all the cranking lately. once i did that i took it to get the alt checked out since my guages said it only had 13vdc and never would get any higher. turned out my alt was bad..... well i replaced that and now the guy checked it out again and it is still not charging........ he said something about a safety measure that they put in, a fuesable liink, that could be blown and prevent charging. has anyone else heard of this.

[SteveBricks]

You can't really diagnose any of the other issues until you get the batteries/charging system problem sorted out, but it might be that continued low cranking voltage caused the FICM to fry. There's a testing procedure for it in this link: 6.0's, FICM's and Cold Start Problems - PowerStrokeNation

[Samuel1941]

Can't address the rough start.

But will note that when you replace batteries, they should be done in pairs. (You mention in your post that you replaced one.)
If the batteries are not almost perfectly matched (same age, same capacity, etc), the weaker of the two will act as a parasite and continually drawn down the stronger battery. (The drawn down amount will depend on how mismatched they are.)