Truck dies. slowly, like starving for fuel. ???

cbuttre835 · Nov 21, 2012

Sorry, this got long winded.

Backstory:

I got some bad fuel in the front tank at some point. Bowl would be full of rust; I'd drain it as often as once a week, whenever the WIF light came on.

Truck always ran OK. Till one morning on the way to work; it quits. Quickly; like an electronic die-off. I thought CPS; replaced it with a NOS IH CPS, still same problem; got a brand - new one from Oreilly's; that appeared to fix it.

Thennnnn, it almost quit again. While running on the front tank. I was down to a little less than 1/4 tank so I hit the switch. It stumbled and missed and smoked and popped for a 1/2 mile or so then cleaned up. Bad fuel, I said to myself. I made it home and parked it and gathered parts for a Bronco tank swap.

Truck also had a fuel pump leak for about 2 years, so I replaced that. Replaced o-rings in the bowl. Installed the Bronco tank; filled it with clean fuel from a can, I ran it for 20 min or so in the driveway. Ran great, no leaks. Woo-Hoo.:redspotdance:

I noticed it being hard to start the first couple times, but since I had the banjo bolt off and fuel pump replaced I chalked it up to air.

I also noticed when it starts it doesn't really "hit". It sounds almost like a roll start of a manual clutched truck.

It quit again tonight, a half mile from the house. Acted like a gasser starving for fuel. No CEL, tach looked fine, just "choked" down.

I let it sit for 5 min while I contemplated stuff like how much it would bring for scrap metal. I remembered my half-throttle trick when the IPR died, I got it started (a sluggish, lumbering start) by cranking for 8-10 sec at half throttle and hammered it on back home.

Fuel pressure on the schrader valve is fine (45 PSI) when the truck is running. ICP duty cycle looks "normal" 11-13% at idle. EOT is wierd... like 350 degrees. But the other truck has always done that on my cheapo Palm scan tool.

I"m at the end of my rope and asking for suggestions. Plan at this point is to re-rig my "live" fuel pressure gauge and zip tie it to the antenna or something so I can read it constantly while driving; and maybe do the same with HP oil press (I have a 5k PSI gauge and 5K psi working pressure hose, that should suffice?)

Any other thoughts? Acts just like a lawnmower or something you "choke" down. :lookaround:

TIA.

mandkole · Nov 21, 2012

Agree with getting on-road fuel pressure information and your troubleshooting so far. Keep going...

cbuttre835 · Nov 23, 2012

OK rigged up the fuel pressure gauge, fuel pressure stays up. Between 45-60 PSI on the pulses (didn't have a liquid filled gauge).

Time to fire up the scan tool and / or get an HPO gauge.

cbuttre835 · Nov 25, 2012

Tried to drive today; first time out in the daylight. When it smothered down it went to puking oil smoke; the CEL set, and the ABS light lit. Had no throttle response...ended up just idling till it finally died.

Anybody ever seen a turbo runaway? I thought that's what I was fixin to have. :lookaround:

I pulled off to the side of the road, waited a few minutes, it re-started, and ran well enough to get me back home. Did not smoke any more either. :doh:

I would think a cut oil-fuel (middle) injector o-ring wouldn't re-seal... where else would it have gotten oil in the fuel?

Blown turbo seal? Stuck IPR blowing an o-ring and letting it re-seal?

Blow-by has been routed to the atmosphere on this truck... turned the little valve cover thing around with a heater hose draped over the master cylinder, and plugged the hole in the intake.

Stumped. Time for the scantool for sure.

cbuttre835 · Nov 26, 2012

Update: scan tool data....

OK so I put the scan tool on it.

I also checked the IPR sheet metal nut to make sure it's tight, just on a whim.

IPR duty cycle ranges from 15-30% at idle. That does not look right. I thought normal would be 9-12%

ICP at idle is 1300-1500 PSI. That, too, seems high; I thought 750 PSI?

Here is the real kicker: EOT started at 180 degrees and after 2-3 minutes (motor started cold) it was showing 400+ degrees F. When I attempted to run the KOER Cyl. Contribution Test (had a reallly lopey idle at this point) it would throw a P0196 EOT range/performance code. It should run the test because EOT has to be over 175 or so (and it was...)

Question: does the chip being in affect this? Did not go through the trouble of pulling it.

What little I understand about programming tells me that the high ICP / IPR Duty Cycle could be due to the PCM thinking the oil is way hotter and thinner than it actually is? Or does EOT not play a part in that?

Still stumped, but getting there. I hate to spend $300 or so for a new IPR, EOT, and ICP sensor.... I'd like to know which of the 3 it might be.

Any other tests I could do?

mandkole · Nov 26, 2012

You don't seem to have a mechanical issue here-- sounds more electrical.

HPO and pump are not being managed if DC is moving between 15-30% at idle. You could have some crud stuck in the IPR valve or possibly an electrical issue. Plus if there is another electronic issue, it will cause the IPR act up.

If the EOT sensor sets a code, it goes into default -- IIRC 68F to 212F. It affects a variety of parameters (timing, idle speed, and allows CCT @ 168F). Its a cheap sensor and it may be unhappy. Have you tried unplugging it? If its unplugged, it should allow a contribution test even if the oil is not at temp.

Next steps
1) You still have the chip in? Pull the chip--my truck acted similar when I tried to run a dissimilar PCM coded chip on my rig before it was retuned. Its worth a try as you may have something going on there and you can eliminate any outside influence.

2) Check all of your electrical connections and wiring around the EOT and IPR. They are separate circuits but make sure the idle won't change when they are being wiggled.

cbuttre835 · Jan 26, 2013

mandkole said:
You don't seem to have a mechanical issue here-- sounds more electrical.

HPO and pump are not being managed if DC is moving between 15-30% at idle. You could have some crud stuck in the IPR valve or possibly an electrical issue. Plus if there is another electronic issue, it will cause the IPR act up.

Different IPR and repaired harness today. Truck now idles 11-14% @ 750-800 PSI. But it still acts up.

Next steps
1) You still have the chip in? Pull the chip--my truck acted similar when I tried to run a dissimilar PCM coded chip on my rig before it was retuned. Its worth a try as you may have something going on there and you can eliminate any outside influence.

2) Check all of your electrical connections and wiring around the EOT and IPR. They are separate circuits but make sure the idle won't change when they are being wiggled.

Have not pulled the chip. Wiggle test is OK.

After the IPR swap I fired it up, was hard to start I presume because of the HP oil draining into the valley. It started and idled great. I let it idle 2-3 min and then started ramping the throttle up. Around 2000 RPM it started doing its "thing" again... IPR DC % increased steadily as it tried to keep up; I held the pedal steady and it brought the DC % up as RPM collapsed... it was 54% when it finally died. Interestingly enough it didn't set a CEL / P1211, but it was only at 54% for a split second.

It's a pain to start after it quits. Can't hear injectors firing; and I know that fuel press is OK. Not seeing its 500 PSI ICP I'm sure.

I'm wondering if the HPOP is going out or somehow starving for LP oil???

Those who have had a HPOP fail, how did it go out?

cbuttre835 · Feb 18, 2013

cbuttre835 said:
Different IPR and repaired harness today. Truck now idles 11-14% @ 750-800 PSI. But it still acts up.

After the IPR swap I fired it up, was hard to start I presume because of the HP oil draining into the valley. It started and idled great. I let it idle 2-3 min and then started ramping the throttle up.

Fixed. Apparently I've developed an oil consumption problem; and losing that oil in the IPR swap put me about a gallon low.... I got it back into the safe range; and it runs like a champ. IPR DC is where it should be; had 3-4 hard starts (air in HP oil system) but it fires right up and runs right again.

Smacking my head for not checking the oil after I swapped the IPR and lost a couple pints... :morons:

Powerstroke Cowboy · Feb 18, 2013

The 7.3L will do that if run low on oil.. Both my brothers have done the same thing..

Infact when I saw the title i got in here to say check your oil level! But i see you took care of that allready