(10-21-13 update=solved)

(10-16-13 update)


I have a 2002 7.3 4x4 c.c automatic, with about 175,000miles. Went on a hunting trip and got back and truck would not start the next day. On the way home from the trip, the CEL came on, stopped to check the oil and give a visual, everything was ok under the hood and on the gauges, got back on the road and the light went off about 10minutes later. Truck restarted fine after a diesel stop. It’s been running just fine no issues. When I try to start it I cannot get a long crank out of it, it will only turn a couple times when I hit the key, and its like the starter disengages on its own. The reason I haven’t changed the starter is from the AE codes I’m getting.

Currently;
No chip, all stock
oil level is good, oil has about 4000 miles
I replaced the CPS no change
I replaced the GPCM no change
I unplugged the ICP and checked for oil, no oil in it and it did not start, I plugged it back in
WTS light works as it should
Fuel pump runs when key is turned

Im thinking its not the PCM because the WTS light is working,the fuel pump is energized and it still will not start when I unplug the ICP,so im thinking the PCM is working and preventing it from starting……??

I plugged AE in and could only operate the KOEO tests. I receiveda U0683 GPCM code, I replaced the GPCM and it still will not start. Retested after GPCM install, cleared codes, retested and no codes are coming on. Still not starting

I plugged the AE in and monitored the Injector Control Pressure before and during start up with the ICP plugged in, and it only registered 28.28psi with the key on and WTS light off. When I turned the key to start it only turns a couple revolutions and quits/disengages, during the starting, ICP pressure was 28.28 and climbed to 500 psi a split second after the starter disengaged.

The ICP reading from the AE is telling me it may be a oil pressure issue?....IPR…? is it correct that there should be 500psi built up before it starts….??

Things to check when I get home are;
is there oil in the HPOP reservoir
do the tach and oil psi gage move when starting
couple other sensors ive been reading about

I will update what I find……any help or advise would be appreciated thanks

 

28 is definitely not enough to start. 500 is required. Probably an IPR issue.

Also, you have a 2002. So your tach shouldnt move when cranking.

 

thanks for confirming the psi, and the info on the 2002 tach, much appreciated.....time to start reading about IPR's

 

The above bolded makes me think there are two problems here. ICP should be about 500 PSI. Have you load tested the batteries and checked amperage draw to the starter while cranking? Have you cleared the codes with AE and then retried starting? The reason I mention it is that then you would have the code (or codes) responsible for your current situation. Who knows when the codes you pulled were stored?

 

Often the coil is what fails. If you want you can get a rebuild kit and hope that it is a dirty IPR or leaky IPR oring, but more often than not it seems to be the coil.

Changing the coil is easy. 5 minutes. Problem is they are not sold separately. You can buy an IPR cheaply online from Riffraff. I paid $319 from the dealer.

If the IPR fails, most of the time it wont set a code. But you can check IPR duty cycle with an AE.

 

What is battery voltage while cranking? AE can tell you.

 

carbonfootprint, if its easier, your ODO can also tell you since you have an 02 with the digital ODO.

I find it easier for me.

To access the menu, hold the ODO reset button, and turn the truck on (you dont have to start the motor). Keep holding until it says TEST. Press the button until it cycles through and you see the voltage. You can then start the truck and see running voltage. The only issue is you cant see voltage drop when its cranking, but I dont think the OBDII one will either, but someone will have to correct me.

 

thank you for the reply. The ICP was changed about a year and a half ago, i just checked for oil in the connection, there is no oil present. when i checked with AE i was getting the U0683 code, a communication fault with GPCM and PCM. i changed the GPCM and cleared codes, the U0683 code was gone and still no start. no codes are coming up on restests

 

i didnt know AE could do that will try it. batteries have 12.6 just sitting no load.....will see what AE says while under load

 

thanks man, everything helps, i will be testing the voly under load.....may not ba able to report back tonight.....will post results as soon as im able.....much appreciated

 

Chris is on target. If cranking voltage is below 10.5 volts, it will not fire the injectors.

 

You can always try a jump start from a running car to help determine if the batteries are bad. When mine wouldn't start, I could jump the truck off with the wife's mini-van.

Also, for giggles, check the relay in the fuse box under the dash. If the relay is failing, it could disengage when trying to start. I've had a relay go bad, costs $25 to replace.

 

Stick a volt meter in the cigar lighter and watch what it does. If your batteries are weak you'll see it.

 

Thanks for the heads up about the voltage, I think it pointed me in the right direction. HookedAE up and tried to start 3 times 1st crank volts went from 14.4 to 11.8 under load no start, 2nd try volts went from 11.60 to 9.4 under load nothing, 3rd try 10.6 to 8.9 under load nothing.

So I have the batts and alt out to test.....I'll update wirh what I find.....thanks

 

10.5v are required to start. So it should have fired the second time assuming you had enough current, but you are seeing a lot of voltage drop between starts. Those batteries seem very weak. I would get them tested. It could be bad batteries, but even if something else is wrong, fighting the fix with bad batteries will get you no where.