As stated above....

The truck started starting very rough and with no throttle response at 50 degrees and under.

Started plugging it in and things were fine...

Got 8 new glow plugs and a glow plug controller...
Installed those...

No help...

Full oil change and filter along with empty the HPOP resevoir and refill with new oil...

This morning it was 38...
Would not start. Would not even hit.

Seems like it is not getting fuel...

Leading up to this, when it get cool it will start and idle very rough until it warms up a bit then it is fine. However, during that time, it has no throttle response and will not rev...

plugging it in does fix the start issue, but only as long as the block stays warm...

How after new plugs, controller, and oil change is it still mad at me??

Thanks

 

welcome to the wonderful world of a 7.3L powerstroke in cold weather, what kind of oil are you running? a 5-40 synthetic would be better for cold weather, but probably still not gonna start without being plugged in, have you tried cycling the glow plugs a few times before cranking it over? it helps me sometimes

 

I am running a 10w-30

I have tried to cycle the plugs twice also...

I am under the impression it should be starting now..

Just not sure why after all this is done, why plugging it in is the only way to start her...

 

some will argue with me, but the 7.3's are terrible at starting in the cold, anything below 48 degrees for me requires plugging it in and or ether, just something that the old things seem to need

 

I would not argue...

I think the fact that it starts worse and worse the cooler it gets points to a mechanical problem...

Just can wrap my mind around what it is...

I can going to go back and check that the relay is working and such, and install a new fuel filter...

But still no good idea on hows and whys yet...

 

well i don't know if it's possible, but if some how the engines lost some of their compression it would start harder, i think it works both ways like to high and it's hard to crank over and to low and it doesn't start without assistance which is the only way i can explain it if you have all new systems ie: glow plugs, relays, batteries, I guess you could try some huge batteries like 1000+CCA batteries, which would in theory only help with cranking ability, but they would also supply more power to the starter at any given time when it calls for it, something to think about

 

so I changed the fuel filter last night, and it was pretty cruddy..

The truck started this morning without being plugged in...45 degrees.

However, it was very rough idle and would not rev...

Gave it a minute or two, got in and took off..

No power, then all the sudden, zooooooom....

What causes that? and how does plugging it in fix it?

And it was not like it got better and better and better, it went from

"wow this is scary how little power it is making, to Holy crap this is fast"

 

Is it possible your oil pump is going bad and when the oil is cold it is unable to suck enough of it up to send to the HPOP when starting it cold.

That is all I can think of.

 

The resevoir was full the last time it did not start, so the pump should not be an issue??

Or are you saying the HPOP is bad?

 

I am saying that you oil pump could possibly be not supplying enough oil when cold or sucking air. That could possibly cause the HPOP not to function properly untill warm.