It's a cold start problem now. Replaced everything else.
 

1999 24V, 138k miles, new VP44, fuel filter, air filter, oil, 2 new batteries, airtex lift pump giving me ~20psi at idle. Other than that it's bone stock.

The truck WILL NOT start when it's cold. I have to crank it over for 15 minutes until the temp guage starts to move and then it will start and run everytime. When I start it and it's cold, it idles rough for 5 seconds, then dies. I have to repeat this process for about 15 minutes(which is probably killing my batteries and starter)until the temp gets high enough and then magically it fires right up like nothing was ever wrong. What could possibly cause this??? I've spent about $1600 so far trying to fix it and nothing has helped it so far. :(

check the air intake heating grids....
https://www.dieseltruckresource.com/...=heating+grids

I would agree with checking the grid heaters. Also make sure you fuel is not gelling? How cold is it where your at. Also do you plug it in at night? Does it happen first thing in the morning and not in the afternoon when the temps may be warmer.... Need more info...

I live in AZ and I don't think it has a plug to plug in. It's about 95* right now so I don't think temp is a problem. It doesn't matter what time of day, if the motor isn't slightly warm it won't start.

check the coolant temp sensor. I am thinking it is telling the computer that the truck is warmer than it actually is, in turn the vp44 is not injecting enough fuel to start the engine.

Any way to check it or is it cheap enough to just replace? At this point I'm willing to start replacing just about anything to fix it. :(

I'm wondering about those grid heaters now. Any way to check to see if they're working? Do I even need them if the temp is around 95*F here right now?

If you have a scan tool you can look at the data stream and see what the coolant temp is reading. At a cold start it should be the same as the air temp.
My truck will start without grid heating down to 0 degrees, so I do not think the grid heaters are your problem.

The guage seems to be working fine. I unplugged it and it dropped to zero and the check engine light came on. Next time it doesn't want to start I will try unplugging it to see if it starts better.

I messed around with the grid heaters and the heaters themselves seem to be working and they draw an assload of juice, I'm just not sure about what engages them and when it's supposed to engage them?

Ok, I just went out to start it, it didn't start. I unplugged the coolant temp sensor, cranked it over and it wouldn't start. I tapped a + wire to one side of the grid heater post on the intake for a few seconds, tapped the other post for a few seconds, jumped in and it fired right up. It's about 90* out right now and the engine is fairly warm still. Why would I need a grid heater to start in this weather?? :confused:

I'm not sure if it was just a coincidence that it started right after I did that or if firing up the heaters for a few seconds actually did the trick? I guess I will knwo for sure in the morning when it's completely cold.

I'm so annoyed.....

Sensor
 

Did you replace the Crankshaft sensor? The Crankshaft Position Sensor (CKP) is located on the lower left-rear side of the engine behind the starter motor Crankshaft Position Sensor (CKP) Location. I would check this sensor with a scanner if you have one. Did you check for any codes yet? Since the sensor is located behind starter you need to remove starter to replace.

Sounds more like a CKP to me! The grid heaters have nothing to do with it.

Grid heater isn't the problem, probably has air getting into the fuel system.

Well since you live in 90-95 degree weather then I don't think your problem is grid heaters or fuel gell. As stated above, check your CP sensor.

I think it's an air leak and I think I've got it fixed now. If not I'm going to remove all the injection lines and start from scratch. Thanks to everybody who helped and to those of you who mentioned an air leak, good job.

I'm going to be firing it up every couple of hours to see if it starts. I fiddled with all the lines, cracked them and retightened and I think it's holding it's prime so far. :cool:

I took off all the lines and retightened everything making sure all lines were tight and straight. Got it fired up after bleeding the system and cranking it over. Ran it for a while and it started right up a couple times, but then I let it sit for a few hours and it's back to what it was doing. I'm done. I can't deal with this anymore. I don't have the patience and I obviously don't have the skills to fix it so I'm done. I tried......