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-   -   1996 6.5td idle problems (https://www.dieselbombers.com/chevy-gmc-6-2l-6-5l/115231-1996-6-5td-idle-problems.html)

Irish_Alley 09-11-2013 05:59 AM

1996 6.5td idle problems
 
first off hello from delaware. i have been working on gas motors/trucks now for a little time but this would be the first diesel i have touched. but anyway me and my buddy just picked up a "work" truck in its previous life it was a plow truck. but the body isnt that bad off, shes been parked for the past couple years. then my buddy who owns a welding shop needed another work truck. he has his 04 chevy v10 and my 94 c1500 4.3 its ok for small runs but if we need to haul anything with weight we have to use his 04 or my 79 k20. but my k20 is limited due to 6" lift and 40s. and his 04 doesnt get good mpgs with the box on the back and welder and tools so we need/wanted a diesel was planing on getting a cummins and dropping it into a 89 3+3 but this deal cam along and we picked up this 96. but the problem is/are the glow plugs seam to be messed up. i dont know the full details but my buddy looked at them and said the harness seams to be melted or something. so anyway we tried to start it to get her loaded on the trailer. took about 10-15 seconds of cranking to get her to fire up. once she did she screamed to 2k then back down to about 1k then a couple seconds continued this cycle. during this run she would blow black smoke then white/maybe gray smoke this was alternating with the rpms. dont recall which smoke went with which rpms but it was changing. after 10 seconds of this we shut her down. started to look for other problems. both of us can work on any gas motor fine he has more experience than me in diesels but its not much. so while we where cranking on her i recalled not hearing the lift pump with the key on. so we checked it no power to it. replaced it with one we had and ran a jumper wire to the battery. bled the line and started to crank still same results. now i know the body looks ok with rust but the bolts seam to be hurting, so could this be a ground problem? from what im reading it seams like IP. the pmd is relocated so its not stock but it could be bad. need to find a working one to test her with. but till i find one im looking for other things that could be a problem. i dont know but i think my buddy said the throttle light was on, and when it was doing its thing there was little to no throttle response. now on a side note we had to start her by jumping the starter ( it was getting power but thats it) the guys father came out and told us the PO knew the starter was bad but he didnt want to put any more money into her. he did act surprised when we did get her started and she ran like crap. so till i get a response here i will continue to search for similar problems.

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quick question, how important is it that the batteries be matching?

Mayhem 09-13-2013 05:40 AM

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[/size][/color]
quick question, how important is it that the batteries be matching?[/QUOTE]

This is very important just had a battery go bad and replaced both

Irish_Alley 09-13-2013 05:57 AM

years ago i used to work at autozone and we used to always push replacing both batteries but never knew why lol. thought it was more about money, but what type of problems could this cause?

Irish_Alley 09-14-2013 11:29 PM

ok just a small update. while i was sleeping today (work 2400x0800) my buddy started to work on the truck and said the plug for the pmd was melted. so this could be the problem now just to find another friends to borrow

Mayhem 09-15-2013 07:29 AM

Take apart and clean a grounds especially the ground strap on the rear of the passenger side head get starter checked and clean the block where the starter bolts to it a little grase here will kill a starter fast and that truck being from the north you need to check the oil cooler lines real good where they connect as the clips are prone to failure due to road salt 30 seconds without oil and bye bye 6.5

detroitdiesel idi 09-15-2013 01:48 PM

First off chevy didnt have a v10 engine in 04. 2nd the lift pump runs off oil pressure not volts. Symptoms are most likely pmd.

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If its not relocated

racer55 09-15-2013 03:27 PM

Ok lift pump gets power through the lift pump relay and should have a prime cycle when the glow plugs are cycling.
The OPS is only secondary backup power for the LP and usually only is used for a few seconds after shutdown while the oil pressure bleeds off.

Check for power to each and every glow plug when they cycle,if the harness is suspect(unplug them all and jumper the relay heavy terminals).

There are a lot of fusible links for the glow plugs that can fail if shorted in the factory harness-you need working glows to start it at all times of the year.

If the age is unknown replace with Bosch Duratherm glow plugs.

Also an often unknown procedure with new owners is that you need to crank the engine over as soon as the glow light goes out the first time-the additional short glow light cycles are afterglow and mean to happen with a running engine.

If you wait for the glow light to go out the final time before starting,the glows will be too cold to aid in starting.

When you replace the PMD make sure you install a resistor in the harness cavity-if the old 1 can retrieved use it.

Also make certain that heat transfer paste/pad are used between the PMD and heatsink and torque the mounting screws to 25 inch pounds.

Your symptoms of a racing engine can be a defective PMD or a failing IP but get the codes pulled and diagnose the service throttle problem first.

Also verify that the turbo wastegate is operating-running these with no boost can cause serious damage.

Matching batteries is good to have but not a deal breaker-the problem comes when a bad battery kills a good 1-also 700+ CCA is minimum requirement and more is better in cold climates.

When it comes to batteries-check the catalog for whats available in the case size you need-find the highest CCA available,then pick 1 size down.

The reason being is on the highest CCA you can get for a certain case limits electrolyte volume because lead takes up the space and thinner plates fatigue sooner killing the battery- 1 size smaller will give near equal power and last longer in most cases of liquid filled battery's.
Gell cells are a different animal though.

And last but not least-please hit the enter key on occasion when posting,sentences are a lot easier to read than big paragraphs.

Irish_Alley 09-16-2013 05:02 AM

Lol thanks for the tips. And sorry about the big paragraph get carried away sometimes. But I dunno why I put v10. Guess I was tired and trying to think of his engine size might just be the 8.1 but it might be just the 6.0. Sorry for the confusion, and thanks for pointing it out

Irish_Alley 09-21-2013 04:35 PM

OK a little update. Don't know when but we didn't realize it to after we got her home. But the pmd box melted at the plug

So order new one. We know the pmd box got warm before when we had her running but reason for checking the box was because we couldn't get her to run at home. Then checked the pmd box it wasn't warm at all. So put a new one and wire harness on. Now its still not getting warm and still not running.
Checked all fuses all good. Replaced starter due to a bad solenoid. Now lift pump works when you turn the key. The pmd box is getting power don't know what plugs do what but it's still not getting hot

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Forgot to mention Idk but it could be possible that someone might of left the key on. Could this fry the pmd?

racer55 09-22-2013 09:39 AM

Should not have an effect.

PMD must be mounted to an aluminum heatsink large enough to dissipate the heat the PMD generates when operating.

Irish_Alley 09-22-2013 07:43 PM

It was on the heat sink. But right at the plug is where i melted almost like it had a poor connection

racer55 09-23-2013 12:01 AM

Was heat transfer paste/pad used between the PMD and heatsink?

Irish_Alley 09-23-2013 02:56 AM

Idk it was the old one that came on the truck when we got it. Avail it could of been melted the whole time. There is still power getting to 2 of the wires in the plug.

racer55 09-23-2013 12:59 PM

Go through this diagnostic:
www.AccurateDiesel.com - PMD Installation Instructions - Accurate Technical Services, LLC

Irish_Alley 09-24-2013 05:14 AM

Love your balls. No homo:tu:

Irish_Alley 09-25-2013 02:02 PM

ok tested the new pmd all went good till the last step between "B" and "F" supposed to get a ac reading of .8-1.0 we got .2. just for shits and giggles I put the old melted pmd box in just to see what she was reading. very first rotation of the crank she wanted to fire up. so we got her started and she went back to the surging idle she will go to 900 with a touch of white/gray smoke then up to 2k with black smoke. so we might try to borrow someone's pmd and see what she does then

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OK now I'm confused (don't take much) but before calling about receiving a bad pmd I put the new one back in to try and test the f and b post. Well she started up and idled at 800-900 rpms still smoked a little but it was more gray. Went to see if she will rev up it went to 1k and wouldn't go any higher would start to miss and blow more smoke. Shut it off and restarted it only to have her idle at 400. But on my tester I wasn't getting any reading while cranking (B&F)

racer55 09-25-2013 03:18 PM

Wonder if your soot trap/cat converter is plugged causing the black smoke?

Irish_Alley 09-26-2013 05:38 AM

its not black now, more like gray. the black was from the surging idle at the high point (old pmd) the new pmd is now just gray smoke and wont clear up, wondering if some of the injectors arnt spraying like they should? which sucks cause due to the rust i dont think they will come out easy or in one piece :argh:

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also i dont think i have a cat didnt see one when replacing starter but i wasnt looking for one but i know theres no egr

racer55 09-26-2013 06:36 AM

Injectors are quite strong-doubtful that rust would be a factor in getting them out.

Irish_Alley 09-26-2013 05:52 PM

Think the lines will be the problem

Irish_Alley 09-29-2013 04:57 PM

OK a little update. Took cat off no change put injector cleaner in her no change. No throttle response and gray smoke at idle. Put trans fluid in her let her run. Stop blowing smoke at idle

She still runs a little rough at idle and she won't rev past 1100 or so when you have her that high she will smoke. After she warms up no change. Till
You shut her down now she won't idle above 400 with no throttle response

detroitdiesel idi 09-30-2013 02:44 AM

Optical sensor/computer issues?

racer55 09-30-2013 08:13 AM

Don't use auto trans fluid in the fuel.

It has too many additives you don't want and was never meant to burn.

If you want to lube the IP and injectors-use 0 ash marine 2 cycle oil-it was formulated to lube and burn.

Irish_Alley 09-30-2013 09:43 AM

The atf was more only squirted into the filter as an attempt to clean. Switched pmd with a good one no change. Switch with original bad one that surged and she still surged to 2k

racer55 09-30-2013 10:41 AM

Sounds like IP time.

Make sure that the crank sensor is working first though,most aftermarket crank sensors are junk right out of the box-AC Delco ONLY for replacement electronics on these trucks.

Unplug the CPS and try to start extended cranking is normal-no more than 15 seconds though.

If it starts the OS is good,next plug crank sensor back in and unplug OS and try to start-if it starts crank sensor is ok.

Irish_Alley 09-30-2013 03:55 PM

Before we did unplug the optical sensor and she still ran like crap no change. Haven't tried the cps will try sometime. But did unplug the coolant temp sensor and she smoothed out at idle but still ran like crap. It did raise the rpms by a couple hundred or a little less

Irish_Alley 10-01-2013 11:33 PM

ok ran out of time tonight, but i dont know what we changed before but when to start her up (cks unplugged) and she would idle at less than 400 with no throttle response. plugged it back in no change. so i unplugged the optical sensor, i know it was running the other day with it unplugged. but it wouldnt do anything wouldnt smoke, she would try to start but wasnt enough to run.

bigdaddyinacaddy 10-02-2013 01:28 AM

Have you pulled the codes from this vehicle? If the problem is anything sensor related, it should throw a code.

Irish_Alley 10-02-2013 10:45 PM

It won't throw a code unless I unplug a sensor

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well today i got to mess with the truck. something didnt seam right with the fuel in the tank. compared it to a known good fuel and it was lighter and had a different smell, idk maybe injector cleaner. but just to be on the safe side i bypassed the tank and still had the same problem. but now after letting her run for a couple hours the other day she doesnt want to start as easy if at all.

if you can get her started she usally idles around 400 rpms. if she does decide to idle at 800 you can floor it or bearly push the throttle and she wont rev past 1000. it wont miss or stumble if just stops rising.

on a side note, the other day we thought it was a coincident but when my buddy was driving in the driveway when he switched from drive to reverse it would act funny almost like he pressed the gas. it did this a couple times after while changing from drive to rev. kind of blew it off till tonight. once i got her idling around 800 and the whole throttle deal. he decided to turn the dome light on. and again it acted like someone pressed on the gas. not a real big jump in idle but it was something that would get your attention. so im starting to hope/think its a wiring problem, going to start with redoing all the grounds. i see the one on the manifold with 4 or so grounds then the fire wall but is there a diagram on ground locations. also would there be a area prone for ground problems when it comes to salt

Irish_Alley 10-21-2013 04:06 PM

so I think somehow the new pmd is either fried or I fried it. looking back a couple post ago when I tested it I wasn't getting any reading for one of the test. now I got ahold of a #5 resistor and put her in and now im not getting any attempt to start. right before the resistor it was at least running. now nothing, im going to go back and retest it. the pmd the resistor came out of was supposed to at least start but once it got hot would cut out. but its not doing anything also, I put the original pmd (the one that surged) and shes surging up and down every second (700rpms-1500 give or take). unplugged the os and she would surge unto 2k then slowly drop back down to 700 this took about 4 seconds then it would rise back up to 2k and slowly go back down. put new pmd box in and nothing, not a spit or sputter.

racer55 10-21-2013 04:39 PM

Some stuff is bad right out of the box.

Irish_Alley 10-21-2013 06:59 PM

after she cranks awhile it will fire up rev up to 2k then die. idk don't want to buy a ip if I don't need it but im lost on what to check. I doubled checked the pmd with a different meter and I was getting about .6v on the b and f plug

bigdaddyinacaddy 10-21-2013 10:19 PM

Is this pmd on an extension? My pmd acts funny sometimes as well. Not as bad but I have had to replace the extension cable because their was so much resistance it burnt a pin out of it. I now need the short one, the original one because the female pins are getting corroded and shorting, causing random dying, floor it-rev to 2k-act like it's dying all the way back to 800-repeat-all while blowing a mix of black, grey, and white smoke, weird surging sometimes when I hit the brakes. When you say you're getting .6 at the pmd do you mean at the connector of the IP or the connector of the extension? Replace the cables or try removing the extension temporarily. Check all the grounds. Make sure your not getting air in the fuel lines somewhere. Good luck

Irish_Alley 10-22-2013 12:24 PM

.6 at the pmd. Had a hard time getting a reading by the IP. Ill move the pmd back to IP to eliminate the extension. Ill have to find some clear line for the return also

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Just remembered the new pmd has a different plug so that won't work.

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Couple things I'm remembering as I go on. One thing the speedometer will read a speed while cranking. It won't just jump up to 10 but while cranking it will build up like. 5mph per rotation. And there was some mystery fluid under the truck want to say it was about center where the engine and transmission mate

bigdaddyinacaddy 10-22-2013 03:21 PM

The connectors for the pmd are not different. If you have an extension, it should plug into a short cable that then plugs into the ip. That short cable should be grounded on a bolt on the top of the ip. This is the original pmd cable and you should be able to just plug it into the pmd.
The "mystery fluid" you're seeing at the bellhousing is most likely diesel coming from the back of the filter manager in the backside of the valley. This is a common leak, I'm pretty sure mine is doin it too I'm just too lazy to change the lines.

Irish_Alley 10-23-2013 06:00 AM

Its a after market pmd. A gray one

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another thing that i remember is the surging pmd, seams to be melted at the "F" pin. both the old male plug on the relocation harness and pmd where melted. wonder if anything else got damaged. its kind of weird how one pmd will surge to 2k but another if it starts right it wont respond to past 1100 then after you shut her down she wont rev past 500 or so

racer55 10-23-2013 09:12 AM


Originally Posted by bigdaddyinacaddy (Post 1031558)
The connectors for the pmd are not different. If you have an extension, it should plug into a short cable that then plugs into the ip. That short cable should be grounded on a bolt on the top of the ip. This is the original pmd cable and you should be able to just plug it into the pmd.
The "mystery fluid" you're seeing at the bellhousing is most likely diesel coming from the back of the filter manager in the backside of the valley. This is a common leak, I'm pretty sure mine is doin it too I'm just too lazy to change the lines.

The grey and the black PMD's do have different connectors,the wiring is the same but connector housings are different.
http://www.kennedydiesel.com/docs/FS...nterchange.pdf

Also the water in fuel sensor O-ring as well as the fuel heater O-rings are what is the most common filter housing leak.

Irish_Alley 10-27-2013 12:10 AM

took the pmd and harness to another 6.5 and she fired right up. so whats left? i will try to crack the fuel lines at the injectors when i get around to it prob be tomorrow. would i just be making sure they are getting fuel or should i make a pop tester and go ahead and pull the injectors.

i know its getting fuel (smoke while trying to start and it actually starting) so what sensor/switch would mess up like this? if it was mechanical wouldnt it be screwed up all the time? so does this eliminate the ip. what sensor would screw with the throttle to the point that it would only respond a couple hundred rpms(to 1200rpms). then once she ran a couple minutes she would screw up and not rev past 600. then why would one pmd box work but surge and the new one not do anything or if it does start its smoking?

racer55 10-27-2013 08:35 AM

I would say it's the IP.
Sensors throw trouble codes when they are at fault unless the ECM is the problem?

Irish_Alley 10-27-2013 10:10 PM

If I swap ecms is there any relearn or security things I have to deal with?


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