7.3 has me stumped

greenthunder7.3 · May 29, 2013

I have been searching and trying different things on this truck because it seems to crank for a very long time before it starts. first I had problems with the engine not cranking fast enough I changed cables and starter and found something putting a draw on the battery. I unplugged the brake controller because it was one draw and i'm not sure what the other one is. the draw went away when I pulled the fuse with all the modules, might be the gem because there were a lot of faults stored for it but back on subject. the resivor is always very close to the bottom of the threads on the plug. I put a manual fuel pressure guage in the port on the back of the filter base and it shows 60 psi all the time. seems to always show correct rpm. seems that icp voltage is within spec. seems psi and duty cycle do different things at different starts one time I had 60 percent duty cycle and 1200psi before the truck would start but other times it was 40 percent and 800 or 600 psi. there is some oil in the icp pressure sensor and I have noticed after you start the truck and then shut it off but have the key on that the icp reads pressure sometimes is says 20 sometimes 90 sometimes 120. it should read 0 shouldn't it? when I unplug the sensor and plug it back in it goes to zero but if you don't do that it keeps on reading the same number. once you get it started it starts good once warm. what am I missing? whats my next step? change the sensor? I am not wanting to just throw parts at this thing any help would be greatly appreciated.

Arisley · May 29, 2013

Well if the ICP sensor has oil in it, you know it is bad. Start there.

When you say the reservoir has oil to the bottom of the threads, are you saying to the bottom of the threads on the plug you pull to check, in other words, it is pretty much full?

Run a compression test on the truck. Compression is one of the things that is needed to start one of these trucks. Check the glow plug system out. Pull the chip, see if that makes a difference in anything.

Charles · May 29, 2013

You have an OBS and a superduty in your sig, and I didn't see any way in your description to tell what year truck you're talking about. I think superduty, but knowing the year would help everyone.

As for the ICP sensor, just unplug the thing and go crank the truck. If it fires right off, then go buy a sensor or then swap with another engine with a known good sensor.

Bigsexy · May 29, 2013

What port did you test your fuel pressure at? Have you tried leaving the icp sensor unplugged and tried starting it to see if anything changes? If your sensor is bad your computer will put your truck into default mod. So if you unplug the sensors and it working you will see a change. If it doesn't change you've found your problem. Try swapping one off someone elses truck you know his is working. If I have problems I swap parts off my brothers truck it makes it cheaper then just throwing parts at it.

greenthunder7.3 · May 29, 2013

it is a superduty. glow plugs and relay are working. the reservoir is almost to the threads in the housing not the plug so i guess that may be my issue? i have messed with unplugging the icp sensor but i don't think i have done it before starting it initially so i will try that. i checked the fuel pressure at the allen o-ring plug on the back side of the filter base. this particular truck does not have a chip in it. and it has no faults. it must have a vaccum leak somewhere because the pump runs alot with key on which may have been half the problem with it draining the batteries this last time because i had the key on trying to figure out the scanner for awhile

Bigsexy · May 29, 2013

There's 2 plugs on the back side of the filter housing. The one on the passenger side is after the filter test that one. If your filters good and there's nothing blocking it, you should see the same pressure as the one on the drivers side. I've had problems with the ring holding the checkvalve inside closed and seen others have stuff blocks the ports.

greenthunder7.3 · May 29, 2013

ok i checked the one on the drivers side rear. are they the same size fittings? and i for got to mention i have a glow plug adapter to check compression but i don't have a compression guage that goes high enough but would a differential pressure guage set up work just the same. i have used it on gas engines before.

greenthunder7.3 · May 30, 2013

started it with icp unplugged today and it made no difference. i couldn't find the other fitting to check fuel pressure all i saw on the passenger side was lines and the drain. i pulled the ipr valve off for kicks and giggles to clean up. i found a write up somewhere once of how to clean them so i'm gonne find that.

Arisley · May 30, 2013

http://powerstrokearmy.com/forums/showthread.php?t=35070

IPR rebuild video and PDF.

greenthunder7.3 · May 30, 2013

Arisley said:
http://powerstrokearmy.com/forums/showthread.php?t=35070

IPR rebuild video and PDF.

thanks

DNewman · Jun 12, 2013

I've got he same problem on my 2000 7.3L 6 speed. I think it might be the HPOP on mine. I've done everything you've done but nothing changes the problem. My motor stopped while pulling my trailer home last night and I changed the CPS this morning, installed new fuel pump, cleaned the IPR, check the ICP plugged in and unplugged all with no change. My truck will start after a real long crank and then idle and rev but has no power when I try to drive. I know it's got fuel to the bowel and to the heads but it stops somewhere between the heads and cylinders. I think the HPOP is pooped.

greenthunder7.3 · Jun 12, 2013

oh i forgot to post i cleaned the ipr valve and that fixed my problem for got to post and say that i had it fixed. i could be wrong but could it be injector o-rings with yours?

Arisley · Jun 13, 2013

DNewman said:
I've got he same problem on my 2000 7.3L 6 speed. I think it might be the HPOP on mine. I've done everything you've done but nothing changes the problem. My motor stopped while pulling my trailer home last night and I changed the CPS this morning, installed new fuel pump, cleaned the IPR, check the ICP plugged in and unplugged all with no change. My truck will start after a real long crank and then idle and rev but has no power when I try to drive. I know it's got fuel to the bowel and to the heads but it stops somewhere between the heads and cylinders. I think the HPOP is pooped.

My best suggestion to you, is to start your own thread. Not bashing, just a suggestion.
It is not a good idea to piggyback on someone else's thread. When you do that, people get confused who they are helping and both parties get bad information. Only reason I am telling you this is your post count. If you are new to forums, especially ours, welcome aboard. If you are an old hand at forums and just joined ours, shame on you.