I've had the truck a few years now, and am still not 100% familiar with the engine or the fact that it runs diesel. Don't get me wrong, I LOVE that its a diesel, and I'm proud as hell that I've got the 7.3L that everyone loves, just wish I had the time and knowledge to know this thing inside out. Here's my issue.
The truck has always been tough starting on cold days, checked the gpr, and the glow plugs, all seemed to test out fine so I chalked it up to being tough starting in the cold - 30F and colder. Everyone I've talked says that the 7.3 is a little cold-blooded.
It's gotten tougher to start lately, seems like it cranks forever. I replaced both batteries, no change. A couple weeks later just about ran out of fuel, chugged along to the station, made it, but it has run rough since. I know, bad on me, fuel gauge doesn't work so I set my trip-meter and didn't realize I was low.
Since then, most of the time it runs rough, sometimes it doesn't. No loss of power, just shakes a little at idle and sounds like hell at speed. Hasn't ever stalled. Figured I picked up some garbage or air since I let the fuel get low, but the problem hasn't solved itself! It is getting fuel, filter is clean, I haven't checked the pressure of the fuel or oil.
Drained a little fuel from the fuel bowl, seemed to run a little better, but didn't go far with it. Just went out and tried to start it after reading a post, and it stilled cranked long and hard, took two tries to start. A side note - as I was draining the fuel, I noticed that there is a wiring harness plug-in on the back of the fuel bowl. The plug-in was un-plugged and wrapped in saran wrap and zip-tied. What's up with this? Shouldn't it be plugged in, is there a good reason why it's not? Anyone heard anything about this?
That said, I read an article on a failed CPS and it said that one of the tell-tale signs is either it won't start at all or takes a long time to crank, then start. Noticed that it doesn't register RPMs until it actually does start, while cranking it doesn't show up. Could the CPS be the answer I've been trying to find?
Thanks in advance for the help, I really appreciate it, and appreciate the patience as I'm practically a diesel engine "virgin" - just happy to be part of the family.