Need some ideas

This could be a little long, but I want opinions on what is going on.

I have had the truck 3 years now and have used several fuel additives (Lucas, Diesel clean, ATF, etc.) off and on. Never really paid attention before, but I hadn’t used one in about 5 tanks and the truck seemed to be starting hard when cold (rattled bad, fast idle didn’t work, hard to start cold, smoked badly when cold). It started fine when even a little warm, just not when it had sat for a few hours or more.

Then one time I didn’t keep cranking until it started and it wouldn’t start at all. It cranked and cranked (plenty fast, just didn’t seem to want to fire). I disconnected the glow plugs and used a little starting fluid and it started and ran decent. Still had the starting issues, but as long as I cranked it until it caught, it would do the usual problems until it warmed up. It had done this once before a few years back when a friend had borrowed it for 5 weeks when I was recovering from surgery, never figured out why as it worked good from then on until I got the truck back.

I remembered that I had not added anything to the fuel for awhile and put a quart of ATF in on the next fill up. After driving it a couple of times the truck has started well ever since. It rattles a little occasionally when cold, very little smoke sometimes until it warms up, the fast idle is working almost all of the time it should now. The friend hadn’t been using additives either.

I am wondering if it is just the ultra low sulfur fuel drying everything out and the ATF lubing it back up or is it something else. Needless to say I am going to keep up the ATF regime unless I have a good reason not to. It seems to work better than anything else I have tried.

Again, sorry for the long post, I just needed to get the whole story out there. Any ideas or did I get pretty close on my diagnosis? Thanks ahead of time for your input.

Sounds more like air intrusion than anything else.

Next time you go to start it up after its been sitting, have somone else crank while you press on the schraeder valve(or vise-versa). If fuel doesn't instantly come spewing out, I would look at servicing your fuel lines, o-rings, change fuel filter etc.

Edit: another thing to consider is the condition of your glowplugs, starter and batteries

It cranks fast. New batteries last year. Glow plugs are something I am planning on checking out. Got a return line kit from Russ, just need time to install (small leaks starting to be noticed).

The thing that stumped me was how much better it became with the only change being the ATF in the fuel. Thought maybe something in the IP was not lubricated enough because of the ULSF until I added it. Also because the Fast idle didn't work w/o the ATF, then it started working again

The fast idle won't have anything to do with the ATF, the fast idle solenoid outside the pump. The ATF could have swelled a seal or oring that was leaking but I to believe that you need or should start with the return lines, especially if you notice it starting to leak.

Going to do the return lines when time permits. Seems pretty straight forward. Got some tips from Russ when I got the kit. Any idea how long it usually takes? I'm a decent mechanic, it's just that I haven't done them before.

Should not take more than an hour or two
1) be sure to deburr the caps
2) use plenty of vasaline
3) put the top o-ring on first then slide the bottom one over that
4) Save old caps, if ya got a leaker reuse the old ones.
Once done dont look at/think about touching them again or you will surely cause a leaker.

Thanks for the responses. I was a little slow to respond as it has been busy.

Sounds to me like your trucks has ***. I would definitely keep up with the *** regime, you're not the only one here who has noticed a difference when adding it to a tank of fuel.