Maybe it is corrosion causing a miss and hit to the grid heaters whereby sometimes they're working better than others times.

 

..........I,ve found bad cam sensors don't always throw a code........1 in particular was my buddys that had to be plugged in at 30*F or it wouldn't start, just spun over like no tomorrow...changed the cam sensor, its been good ever since, prolly 25,000 miles..........kim......

 

If it is, it's not showing up on the volt meter. Same 9-10V area on the gauge. That is one of the first things I monitor.

Any other symptoms that might give away a bad cam sensor?

 

Okay, so after chatting with youn's and some other knowledgeable types, my most likely suspects are in order of likelyhood:
Fuel drain back Either at the return line on the back of the engine or the pickup before the lift pump.
Faulty grid heater.
Faulty cam sensor.

The 1st 2 should be easy to check, the last no so easy.
Right now everything is froze over from freezing rain. This might take me a while without a garage or shelter.

 

Got out there and bled the supply line at the highest point which is my fuel pressure sender through a couple cycles of the lift pump. No air that I could tell. Tried to start it and it took about 15 cranks before it lit. Cracked the line again while it was running and no air that I could see.

 

You wont visually see any air like you're trying. Matter of fact, opening the fuel lines EVER is the worst thing you can do since all you're doing is allowing more air to enter. Only open the lines under a must do situation of when you're changing the fuel filter.

If there truly is a leak somewhere in the fuel system then yes, as the truck sits for long periods of time gravity will cause the fuel to drain back to the tank and then when you go to start up the fuel pump must re-prime the entire system before the engine will fire. Generally there is no random hit and miss events with this too as it will hard start after its been sitting and fire like normal during the day. Parking with the nose of the truck downhill overnight will help offset gravity's pull and prevent the fuel from easily draining out of the lines. If doing so causes better starting then there you go. But again, if the hard starting occurs while you're out and about driving then its not a leak in the fuel system.

 

Mine had done this very thing drove me nuts to find it, I had change the injectors out 8 months ago and it started to show up turned out to be injector seals it was my first gut feeling and as usual i ignored it looked for every thing else now first bump of the starter it fires

 

When I do bleed the system it is from the highest point. And I only crack the line while the lift pump is running and close it before the pump stops. No way air can enter like that. I am going to go over the whole system over Christmas starting at the tank were I installed my FASS lift pump, to the injection pump, then back along the return lines. Just for giggles, I'm going to replace the cam sensor while I'm in there. Anyone have a good part number?
37° this morning. I didn't plug it in just to see what would happen. Surprise, it lit right off. My experience with leaks is they are fairly predictable, but I'll be looking anyway.

 

It's not bring in air what happens it breaks vacuum and runs back to the tank. I should have said that the copper washers where not seated that well they where a odd washer that came with the injectors the new ones where a tighter fit!

 

Exactly. And yes, the injector o-rings can crack, break, or deteriorate over time and cause the fuel line to drain but yet go completely undetected. Generally only a problem for those who've touched their injectors though. But that said..... If the starting problem is random and during the day while driving then its 99% not a leak in the fuel system.

 

I must be missing something. How can it break vacuum while the lift pump is running? I can understand it happening while setting, but not seconds after running the pump. At any rate, it's getting looked into over Christmas.

 

I cant beat this horse enough..... If its hard starting while you're out and about driving then its NOT A LEAK. And all discussion thereof is mute.

But.....touching the fuel system leaves room for leaks afterwards, period. No matter how you want to dissect it, its just reality.

 

Interesting tid bit. Had the high idle enabled yesterday morning. Worked as advertised in the shop with a dummy IAT. Yesterday evening when I started it at 19° I had a hard start. I let it idle and the high idle never kicked in. Went back and talked to the tech and he said if my IAT is flakey it could be the cause of my problems. I have a new one to go on next week.

 

Saturday morning update. 12/20/2014 10:30AM AK time, 0°F.
Let the truck cold soak overnight. After cranking about 10 times it started. Within a minute the high idle started ramping up. 3 cylinder mode never kicked in after 15 minutes of running.
According to the TSB, high idle activates with an IAT below 32°F and coolant below 60°F. 3 cylinder mode kicks in with an IAT below 15°. The last 2 evenings after having the high idle enabled it would not come on, even though the temperature was 18-20°F.
This tells me the IAT sensor is reading high. Maybe as much as 15-30°.
Grid heaters, high idle, and fuel control (mixture) are effected by it.
Just before my hard starts when it was still unseasonable warm I was wondering why my fuel mileage jumped up 2mpg. As it got colder the hard starts started happening.
Though I haven't ruled it out, I'm having a hard time formulating a fuel system problem, the signs i'd expect to see just aren't there. I will know more when I take a magnifying glass (things aircraft mechanics do) to it this week.
The cam position sensor has not been ruled out yet either.
At least I will have some time and a warm space to dig into this now.

 

Have access to a half decent scantool or do you have an android phone?
free app and a obdII dongle and watch it.