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Discussion Starter #1
1995 6.5 3500 dually. On phone so not sure if vehicle info is showing in sig.

Bucked a little then lost power and felt like close to stall in am drive. Pulled over tightened loose battery ground and moved pmd harness. Made it another 30 miles to work and seemed fine.

Heading home now and lost power about 5 miles into drive and stalled. Switched out my pmds and harness and tried w/o harness. No-go. Initially would stay running in park, shift into gear and stall. Now stalling in park.

This am got codes 18 29 35 41 53 63 65 84 91 97 99. Reset and now not getting a code.

I have bad vacuum pump (hole in it) and has sounded like a lawnmower since last week. Also I see oil in my valley. I changed fuel pump recently and everything has seemed fine until today. I drove around on my last bad vac pump for a long time till I had time to fix it so wondering if this is contributing factor or coincidence. Any help while I'm waiting for the tow truck would be greatly appreciated. Thanks again guys.
 

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With that many codes popping up I would say there is a grounds issue to start with. Go through all of your grounds.
Remove each one, clean the contact areas and reinstall. Replace any that are in questionable shape.
Use this link for reference: Grounds-Grounds-Grounds The importance of good grounds.....
Replace the vacuum pump and inspect every inch of vacuum line.
If you have the stock plastic line then I recommend that you replace it with rubber line.
The OEM plastic line becomes brittle junk with time.

Change your fuel filter
Even though you recently replace the lift pump, it may be bad. Perform a lift pump test: Reference Material: Lift Pump/OPS
If it fails the test, replace it with AC/Delco EP158 and replace your OPS at the same time
 

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Discussion Starter #3
Thanks OkDually.
Ordered vac pump this am and will be here in a couple of hrs. I replaced the plastic lines yrs ago with rubber when they snapped off doing an unrelated repair.

When I did the fuel pump a couple months ago (thanks again for the help on that one) I also replaced OPS and lift pump as it was working but was old. Fuel filter manager was also replaced just before that also.

I will grab the vac pump and a new fuel filter. Will also go through and double check lift pump and OPS.

I thought vac pump was dedicated just to the turbo in the 6.5. No vac, no turbo boost.
 

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Additionally now that's its daylight, I also see that the Optical Sensor harness worked its way out quite a bit and some diesel spilled out at connection. Harness clips deteriorated long ago and seems I forgot to ziptie it during pump replacement. Where did the diesel come from?
 

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Additionally now that's its daylight, I also see that the Optical Sensor harness worked its way out quite a bit and some diesel spilled out at connection. Harness clips deteriorated long ago and seems I forgot to ziptie it during pump replacement. Where did the diesel come from?
The Optical Sensor has an oring to seal it into the IP body. If the Oring is bad you will see fuel around the sensor top
 

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OPS, did you put ACDelco OPS?
Remember, this is a 95, the OPS controls the LP when engine is running.

I am not sure what is wrong with the leaky IP, though.
You just have to figure it out.
May be as easy as some fuel lines or as difficult as what Ok described.
If it is a new IP, it should not have any leak from OS.
Be careful when trying fix OS, it is very sensitive and it needs to be in the same exact position/location as originally installed.
 

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Discussion Starter #7
That is where I am seeing it. Sitting on top of the torx screws. Going to clean it up and run truck and see if I can see where fuel is coming from.

So that OS cover would have to come off, and sensor removed to replace oring correct?, assuming that is the culprit?

I either repair an IP under warranty, or replace it again outright.
 

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Is the service throttle light on? Many of the codes relate to the accelerator pedal position sensor. Check the main PCM ground on the back bolt, passenger side intake manifold. should be tight, clean and have 3 wires attached. If good, your APPS may be bad. If it is bad the truck will just idle. You will get no throttle response.
 

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Discussion Starter #9
JNET
I have a couple of the AC OPS purchased awhile ago as well as some auto store brands ones. Had probs with bad OPS when my fuel filter member was leaking and then the fuel pump leaking before replacement. Currently the AC is in there but I have it jumpered right now to work on truck

TommyGunner
No codes as right now since I cleared them yesterday am. No codes set last night during breakdown. Currently, truck starts and accelerates fine again. But I am sure after it warms up and I drive more than 10 miles it is going to do same thing again. I think the leaking diesel is playing havoc with my electrical system again, and then causing the shut-off solenoid to activate.
 

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Usually you can clear up the APPS issue by shutting off truck and let sit ta bit to reset things and restart. But it will come back in a short while. The APPS went out on my truck and it did that. I could restart and drive for a few miles. Got the truck home and it quit working completely. Truck would only idle in park and idled a little rough in gear. Replaced the APPS and all good.
Also a bad ignition switch can throw a bunch of codes.
I really dont think it is your FSS. A short to ground that would cause it to close would blow the fuse
 

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Discussion Starter #11
TommyGunner
I replaced the APP sensor a couple of years back ( very similar symptoms as to what you described) and the ignition harness as well (don't remember why now but was chasing down some problem and it was recommended as it sometimes solves the random gremlins the 6.5 encounters). In my case it didn't fix the problem but it was as least something I could eliminate.

Also when I first bought truck in 2012, a diesel mechanic replaced the APP that didn't fix some surging issues I was having. That time, I think it actually turned out to be the boost solenoid.

Without the APP code, I think the only other diagnostic is the shop scanner right. Any field test you know of?
 

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Discussion Starter #12
Since I am not going to make it to work today and my parts place is bringing in a replacement IP along with my vac pump, my plan of attack is to remove the intake covers again, run truck and locate the leak. Maybe a hose or injector line at pump.

I did replace all the hoses at FFM and pump at pump install. At least this way I am halfway to removing the pump if that OS is the issue.

This truck has served me very well but this downtime is beginning to take a toll on me. I just finally found time over the winter to do the leaf springs, brakes and a CV that had been shot for a couple of yrs. Then the pump went out a couple of months ago.
 

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Discussion Starter #13
Ok got truck turned around in driveway so I can work on it in shade. Stalled a few times just trying to get it to turn around and got some codes to throw. 17 18 35. All pump codes. Dried harness connection and reseated OS and runs without the loud noise that was just starting to happen when engine fired. Cleared codes.

Reseated OS firmly without the rubber dust seal and moved pmd to engine harness. In park, revved to 3k and threw code 35. Drove around neighborhood no stalling yet. Back to driveway , unplug OS and the connection very wet again with diesel.
DTC35 from troublecodes.net
Fuel injection duration -pulse width signal shorter than expected

Possible causes
Wiring, fuel injection duration control solenoid, fuel injection pump control module, ECM

I think I have a defective IP leaking at the OS. With it fully seated looks like it will run, I think the fuel buildup started to push it loose and wiggle stalling the engine.

Looks like swapping the IP today unless anyone here has a suggestion.
 

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There are links in the 6.5L FAQ page on replacing the IP with step by step instructions
 

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Discussion Starter #15
So still orig prob exists with stalling and shaking then dying. Drove short trips in neighborhood to store etc after swapping IP and installing vac pump. Did stall after 10 min of idle after pump replace but I attributed to heater hose fitting replacement(leaned in it one too many times) and having to bleed air out of system). Ran engine w/ intakes off and did not have any visible fuel leaks before reassembly.

Attempted to do long drive to work. Felt great for first 10 min, then rumbled and stumbled. Threw code 41 (brake pedal), replaced burnt 10A fuse. Started back up fine and exited and was losing power and got into parking lot. Unable to restart and got code 13 (fuel shut-off solenoid). Swapped pmds and then relocated both w/o harnesses. No change. Unplugged engine shutoff connection and replugged. Engine starts and runs with both pmds plugged into orig and extension harnesses but no changes in performance regardless of location.

No codes currently. Idles fine, runs rough and stumbles. I have not run it to a stall.
A member suggested APP but I do not have a code for this and this will be my third APP. A new APP has yet to ever resolve an issue I have had. I figured I would pull it and see if I can do an ohmeter test. I am also just wondering if those wires in the valley are just getting hot and giving me probs as cooler engine I am not experiencing the probs I get when it is hot. Also going to disassemble and install some new temp intake gaskets (fel-pro) until I can find the metal ones online. Seem to have a little oil residue getting by. Discontinued at dealer and local part store unable to get metal.

Any ideas or paths to look at?
 

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Install a piece of clear fuel line on the return side of the IP to look for air.
Remove the fuel shut off and gut the plunger, reinstall.
 

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Discussion Starter #17
Ok so truck off while typing in latest update, went to start, no start code 13 again. Wiggled ESO wires w/o unplugging and truck started. I think I am going to replace as much of that switch wire as I can when I have intakes off.

OKDually, I will also check for the air again if I can limp it home. Trying to find a break in the lunch traffic so I can get on my back road.

Also OKDually, what are the "real" chances of runaway engine if I remove the plunger. I did it to my old plunger but with all the probs I have been having lately, I was hesitant to do it again.
 

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Discussion Starter #18
Hopefully on right track with ESO. Seemed to drive "ok" on way home and stopping at auto parts to get some wire, truck was starting to really surge when I pulled in and at idle, pulled tight on ESO harness wire on engine side and engine immediately went to quiet idle and quit surging.
 

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Ok so truck off while typing in latest update, went to start, no start code 13 again. Wiggled ESO wires w/o unplugging and truck started. I think I am going to replace as much of that switch wire as I can when I have intakes off.

OKDually, I will also check for the air again if I can limp it home. Trying to find a break in the lunch traffic so I can get on my back road.

Also OKDually, what are the "real" chances of runaway engine if I remove the plunger. I did it to my old plunger but with all the probs I have been having lately, I was hesitant to do it again.
Slim to none.
 

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Discussion Starter #20
Thank you sir, will do then. More than once that ESO has almost killed me. I have had to captain Sully that thing to the side of the road in more than a couple of instances loaded down with tools or a trailer.
 
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