My 2003 6.0 was running like a champ. I stopped at the gas station on day on the way to work and when I came out it would not start. I was able to start it on a gas soaked rag. when it started, I checked the ficm and had good voltages, hpop was 700 psi idling and got up to 3500 psi when I romped on it. The truck runs perfect when it starts. At first it would not restart when the engine was hot but it would start when it was cold. I was unable to shut it down due to time. I drove it to work and 12 hours later when I would leave it would crank fine. One night while coonhunting, I killed it and 5 minutes later it started right back up with the engine warm. I thought it had worked the problem out by itself some how. ran good for about 2 weeks. Then one day I had to go back to the gas rag, so I shut it down. I talked to a local 6.0 mechanic and as soon as I told him it started and ran good off a gas rag he said ipr. I pulled the ipr today expecting the screen to be broke. It was not. I also checked the icp and it is not oil soake in the plug. While the truck was running, I pulled the plug off the icp and you could hear the engine switch to the factory default. plug it in and you could hear it swith back to the icp signal. clear the codes and it runs great.
Can anyone give me some advise on what now and if there is a way to test the ipr? thanks in advance.

 

Any codes besides the ICP codes when you checked?

 

no codes normally until I unplugged the icp.

 

Did you get numbers on IPR and ICP when it was a crank/no start?

 

no my scanner only work when there is power to the obd2. it does not have power when u are cranking it so I am screwed there.

 

Here is a way of checking to see if you have sufficient high pressure oil without having a gauge or adapter. Strip back the wires about an inch away from the icp sensor connector. Obtain a digital multimeter and set it for voltage (DC). The bn-wh wire is a five volt reference, leave that alone. Strip back the db-lg signal wire and the gy-rd ground wire. Put positive lead on a dark blue-light green wire and negative lead on gray-red wire. Have an assistant crank truck, you need a minimum of 0.82 volts (500 psi) for the truck to start, if you are getting greater than that then you have sufficient high pressure oil.

Aww dang, just went back and saw you're a 2003. This is an easy check on later models but with the location if the ICP on the early trucks it a pain. I'll post a link to an under hood wiring diagram and you can do this at the PCM connector if you want to try it.

Under hood wiring diagram
https://www.ford-trucks.com/ford-man...%20diagram.pdf

 

is there a way to test the ipr?

 

i read a post after doing an ipr search on here about the iat2 sensor. i did notice that looking at mine from the outside it has oil on it. could that be a flag? i will pull it tonight and take a look at it?

 

IPR TESTING WITH A DVM
Pull out the middle PCM connector and ohm out pin #2 of the PCM connector (yellow with red stripe coloured wire) to the positive terminal of the driver side battery at key-on/engine-off. A good IPR should read about 6.0 ohms. Of course your testing the electric side only this way. It could still be jammed up mechanically.

 

Everything checks out fine. What about the crankshaft position sensor? i have heard the connector sometimes breaks or cracks and when the trucks warms up it will open the circuit and when they cool off closes again. the mechanic at the ford house showed me one that had done that. that things is not located in a very good spot to just check it without cause.

 

So it's sometimes a hot no-start?

Next time it won't start, unplug ICP and retry. Pulling it when engine is running only verifies it will default. You need to know if default will allow it to start.

 

it started out as an always no start when hot then it started fine hot now it is back to no hot re start. i will unplug icp tonight and try it. the plug had no oil in it when i unpluged it and the ipr.

 

unplugged the icp and still nothing.

 

Where are you putting the gas soaked rag? And why would that help it start im clueless on this one.

 

That was last hope for an easy fix. Sounds like a high pressure oil system leak or bad pump. It's not making enough pressure when cranking. Time for an air test.