No start cold, starts when plugged in

[Bestautobros]

Hello, I'm working on a 2000 F350 4x4 7.3. after sitting overnight it will not start, even on a nice 65 degree morning. pluged in a hour or so (EOT reaching 80 degrees) it will strat with little trouble. once running, using a Solus, i ran the self tests, glow plug - Passed, contribution - passed, and buzz test - passed, no codes. next morning... no start. tach reads above 100rpm, oil pressure good, ipr 2000, oil rez full, glow plugs ohm good, GPR delivers B+ voltage at valvecover connector. batteries new. Fuel pressure at each head is 50+psi while pump is running, however it bleeds off once the fuel pump stops. Should the cylinder heads retain the fuel pressure when the fuel pump stops? I removed the check valve at the fuel line input at the driver side head and can blow through it in both directions, although much more restricted in the direction leading back to the fuel filter. should this hold 50psi? or is it designed to allow "bleed off"? I'm suspecting fuel injector O-rings, perhaps the ICP sensor. it appears wet at the plug in, but other than that it appears opperational on the scanner? any suggestions would be much appreciated

Bill

[Bestautobros]

after replacing the fuel injector O-rings the truck will now start without plugging in the engine heater. It still however has an extended crank in the mornings, and this appears to be somewhat intermittent. I suspected the fuel line check valves at the heads, however, after ordering one from Ford ($50) i checked and the new one i was also able to blow through it in both directions. my next thought because the truck sometimes starts better in some mornings than others, is an electronic problem. Due to some seepage at the ICP sensor (oil coming from the electrical connector) this is my next guess. I ruled it out before as i had watched it functioning on the scanner. Any Thoughts?

[POWERSTROKER1]

If the ICP sensor is leaking replace it.

[Bestautobros]

Nope, replaced it (icp) and still starts hard cold

[97 golden stroker]

how is the fuel in the system if it is too old it will give you some truble. but you may want to drain some of the fuel into a clean container and see if you can see if anything odd about the fuel. and maby see if it has fuel pressure in the cold mornings.

[Bestautobros]

Fuel looks great, it looked good before i did the FI o-rings. and the customer has ran it through a couple tanks since they were replaced. Should the fuel pressure in the cylinder heads retain pressure after sitting over night?

[Bestautobros]

latest update... after the customer had driven the truck a week or so (post O-ring repair) the truck had a code P1670... and a KOER code P0476, and a Cyl cont. code P0272... i feel tracking these codes down would be a rabbit trail since the truck runs fine after only a few minutes of warm up, no missing. Its Current symptoms are now:
-Tries to fire after a few seconds of cranking
-Lopes or dies once it fires up
-Temperatures are reaching 30ish degrees here in the mornings
-no plug in needed for it to attempt to start

I am comparing how it should start to 96 PSD we have that has never needed plugged in

[cblackb]

This sounds like what my truck was doing when I first got it and I pulled my hair out trying to figure it out. Here is what the problem was: Everything was working correctly, but not enough amps were making it to the glow plugs for them to heat up correctly. The reason was that my battery ground cables where they attach to the block were corroded underneath. Take ALL the cables off the truck and shine them up with emery cloth and also the surfaces where they attach. This means the positive and negative battery cables and also the big wires on the glow plug relay. This fixed mine. I even replaced all the glow plugs and it didn't fix it until I did the above. Also make sure that you get the batteries LOAD tested to make sure they are good. If the batteries aren't putting out the juice, it's not gonna start correctly. This may not be the problem but you should check it. Hope this helps.

[Bestautobros]

I've been eyeballing those connections at the battery for a couple weeks, think i will give that a shot in the morning, thanks for the input

[Bestautobros]

cleaned the battery terminals and replaced alternator, bad diodes draining batts. problem was still there. after hearing from a few sources that the injectors could be worn or sticking, i pulled them once again and measured the poppet clearance, they were all out of specs. thank you Rosewood Diesel (DIY-injectors.com) there's a good description on how to measure them here. I will have them back just before Turkey day and see if this does the trick...