O.K., where do I start?! About 6 weeks ago, I purchased my first diesel truck. Up front, I have never owned one before, and have a very small knowledge of diesel engines. I have worked on gassers most of my life, and am pretty good with wrenching on them. After being screwed over by "shops" 15-20 years ago, it was either learn or buy a gallon of vasaline!

Anyway, here is what has happened;
I bought the truck off of eBay and flew up to New York to pick it up. While I was there, I also bought a P.T. Cruiser off of him at the same time. I picked up a tow dolly from U-Haul and towed it back to Tennessee with the Suburban. For the first few hundred miles everything was fine. It had a sputter to it every now and then.

Once I got it home, I drove it about 750 miles of daily driving. The sputtering persisted and was inconsistant, and really infrequent. It did actually stall out on me about 4 or 5 times. Usually pulled over, turned it completely off and it would fire right back up and I was on my way. It began to concern me. I ran into a guy that I saw had the exact same truck as mine and explained my problems to him. He said that it was most likely the PDM. He showed me his setup with the PDM, which was a SSDiesel PDM and cooler bolted on top of the left side of the intake. He told me that if I did the same thing the problem would stop. Due to time and money I hadn't had the chance to get that done yet. So, I continued to drive the truck.

PROBLEM! I drove up to Ohio, with a U-Haul trailer to pick up a "friends" things and bring them back down here to Tennessee, as he was moving here. We drove about 320 miles without any problems. All of a sudden the truck just died. Being that this seemed to be the same "stalling" problem I had had, I pulled over, turned the key completely off, and tried to start it again. The engine would fire, rev to about 2500 RPM for about 2 or 3 seconds, and drop back down to 1000 RPM. The engine ran very rough, and was blowing black smoke. I also noticed on the last attempt to start it a burning electrical smell. I also had absolutely no response from the accelerator. You'd think it would sputter or some response to the pedal, in some way, but nothing!

Once we accepted the fact that we were pretty much dead in the water, we called AAA. It was pouring rain, and getting stuffy in the truck, so, as we sat in the truck, we turned the key on to at least run some air through it with the blower motor, as we couldn't put the windows down with the rain as hard as it was. With the key on, in a matter of about a minute or two, we noticed electrical smoke coming out from under the windshield side of the hood. I immediately shut the key off, jumped out, popped the hood, and saw the smoke pouring out of the vents on top of the plastic intake cover.

We just sat there then, and waited for AAA. We finally got the truck back to my "buddies" house. The next morning I went out to see what I could do with the truck. I tried firing it up, but nothing. All it did was crank. Not even the jump to 2500, then to 1000 anymore. All it would do was turn over. I then noticed, with the intake cover off, that the PMD had obviously been replaced, because it was wired and just sitting on the intake. I also noticed a melted burn on the PMD's plastic about the size of a dime. I then went out and picked up a PMD, in hopes that this was it and would be the cure. No luck. I plugged in the new PMD, and still, all it did was crank. I read somewhere that, with the key on, if the fuel filter bowl was filling up, that the IP was good. I removed the cap and filter, had a friend turn the key on, and watched the bowl fill up. I removed the front left injector line, and noticed no fuel coming out of it with the key on. I also realized when the key was on, you could hear a "clicking" noise coming from the injector pump. This was a noise I had not heard before.

I have no real idea what the problem could be here. I am thinking that the PMD went out, and because I kept trying to restart it, and leaving the key on, I fried the IP. Any input? Could this still be something simple? I have not yet tried to pull the intake and check the wiring. That was going to be my next attempt. With four small children, all in school activities, & work, I haven't had the time until here this weekend.

I thank you in advance for any and all input! :)

I am sorry, this is a 1999 GMC Suburban 4x4...... Could someone also explain why this is listed as a 1500, but everything under it (suspension and axles) says 2500 - 3/4 ton. Even the title lists it as a 1500, 1500 on the doors, but 8 lug axles and HD suspension.

Thanks again

Let me try to understand this:

Is the PMD on a heatsink sitting on the intake? or no heatsink? or still on the IP? or no heatsink not attached to nothing?

If it ever burns, usually cause the PMD to burn because those transistor can get very hot. When it burns, it may burn the cable that it attaches to.

No Heat sink. The pdm is just laying there, hooked to an extension cable, laying on the intake. Pure laziness, and the lack of a decent mentality to do it right. Musta been the dealership!:D

I'm also thinking I burned up the cable, and would be a lot happier if that was it!

Well, that cause the PMD to burn.

When you plug in a new PMD, do you put it in a heatsink? and make sure you have resistor in there also.

That is a new PMD that you try not "used but good" or "good used" or variation thereof?

This is what happens when we ignore the symptoms our vehicles throw at us. cant believe anyone would drive long distance when it had a stalling issue before and someone actually told you the issue, no investigation was done.

Im impressed the PMD lasted that long. The new one you bought, does it have a resistor plate inside the connector, like J said? Could just be that, but dont run it without a heatsink.

get a new extension cable and heatsink that will take it out to the bumper.

The clicking might be the fuel shutoff solenoid on the IP, it shares a power source with the PMD, if the PMD is shorting out it could be cycling power, causing the shutoff solenoid plunger to move up and down causing the click noise.

First, we don't need to state the obvious, or be sarcastic about it. Ya, maybe I shouldn't have run up there, but I was trying to help out a friend. I already got shit about it from my wife. Don't need this from you. I came on here to try to get some help to get my truck fixed, not listen to this crap. Also, someone else I know, that knows this truck, said the sputter and stall could have been from h20 in the fuel. I put in some additives, and about half a bottle of lucas fuel treatment, drove it about 400 miles before I went up there, and there was no stalling or anything. I assumed the problem was solved. Also, I never had any SES light or anything.

Well, being that I have four children, and this is going to be our family vacation vehicle and my toy, I'm about to pour some money into it. About $7000.00. 4" exhaust, new IP, Improved PDM & heat sync, 80 HP ECM (thats for me :)), routing the PDM to the bumper (thanks for that tip), marine injectors, new vacuum pump, hi-flo water pump and improved cooling fan, K&N intake system, #9 resistor, bully dog triple gauge pillar set, new instant heat glo plugs, and I'm thinking just for the redneck ass hell of it - 6" lift and 35's on centerlines. I'm also looking at the possibility of a new Bamks turbo. I have been looking at a lot of this from "ssdiesel supply".

My issue now is, as I browse the internet, looking for parts, I hear a lot of places that are blowing smoke up your ass. Is SSDiesel reputable? Any other ideas at what I should also do, along with the improvements I intend to make? I'm also picking up the GM 6.5 shop manuals on this thing and doing all of the work myself. This should be fun! Thanks for the input!

Well this is for you and others to learn, want to make sure people understand not to run with an oil light on, or the things like this on a 6.5. Its the internet, dont get so worked up over it.

I just looked at Heath, Kennedy, and SSDiesel Supply. SSDiesel is by far the best value... WHY? Usually when it's cheaper, it's just that.... CHEAPER! Why should I buy a new IP from Heath for 1800, when I can get rebuilt from SSDiesel for less than half? Especially when these seem to be going out every year or two? Also, what is better PMD w/ heat sync, or isolator?

Well, I'm already frustrated with a truck I just bought that I have to pour money into.... I don't need salt dumped in the wound. I had NO service lights on. All the gauges were running fine and it just frickin died. I was pissed.

First, we don't need to state the obvious, or be sarcastic about it. Ya, maybe I shouldn't have run up there, but I was trying to help out a friend. I already got shit about it from my wife. Don't need this from you. I came on here to try to get some help to get my truck fixed, not listen to this crap. Also, someone else I know, that knows this truck, said the sputter and stall could have been from h20 in the fuel. I put in some additives, and about half a bottle of lucas fuel treatment, drove it about 400 miles before I went up there, and there was no stalling or anything. I assumed the problem was solved. Also, I never had any SES light or anything.

Well, being that I have four children, and this is going to be our family vacation vehicle and my toy, I'm about to pour some money into it. About $7000.00. 4" exhaust, new IP, Improved PDM & heat sync, 80 HP ECM (thats for me :)), routing the PDM to the bumper (thanks for that tip), marine injectors, new vacuum pump, hi-flo water pump and improved cooling fan, K&N intake system, #9 resistor, bully dog triple gauge pillar set, new instant heat glo plugs, and I'm thinking just for the redneck ass hell of it - 6" lift and 35's on centerlines. I'm also looking at the possibility of a new Bamks turbo. I have been looking at a lot of this from "ssdiesel supply".

My issue now is, as I browse the internet, looking for parts, I hear a lot of places that are blowing smoke up your ass. Is SSDiesel reputable? Any other ideas at what I should also do, along with the improvements I intend to make? I'm also picking up the GM 6.5 shop manuals on this thing and doing all of the work myself. This should be fun! Thanks for the input!

You have NOT answer my question, we are trying to help you.

You won't be the first and the last, most of us have the same issue.

We are not telling you to put all the money just get it running first.

I am sorry, this is a 1999 GMC Suburban 4x4...... Could someone also explain why this is listed as a 1500, but everything under it (suspension and axles) says 2500 - 3/4 ton. Even the title lists it as a 1500, 1500 on the doors, but 8 lug axles and HD suspension.

Thanks again


The base engine for all variants was the small-block 5.7 L (350cuin) V-8. The big-block 7.4L (454cuin) V-8 was optional for the 2500 series. The optional 6.5 L Turbo diesel was available on all models - though rare on the 1500 series. The 6.5 L Turbo diesel]] used in the Tahoe was reduced power to 380 lb/ft torque due to the limitation of the 8.5-inch axle capacity. 1500 Suburbans with the 6.5 L Turbo diesel used the 14 bolt axle from the 2500 series.

Well, that cause the PMD to burn.

When you plug in a new PMD, do you put it in a heatsink? and make sure you have resistor in there also.

That is a new PMD that you try not "used but good" or "good used" or variation thereof?

I am not understanding "used but good" or "good used"

The new PMD is a Dorman replacement. The one that was on it was stanadyne.

I haven't gotten the heatsync yet. It should be in route to me now. however, the heatsync not being there wouldn't keep it from running.

PM sent

I haven't gotten the heatsync yet. It should be in route to me now. however, the heatsync not being there wouldn't keep it from running.

So it was new PMD.
No, heatsink will not prevent it but if it ever start. It will generate enough heat to ruin your new one. Good news is never start. My guess is that you may have to change the cable from the IP commonly known as IP harness. This is the one that hook up the IP with the ECM and PMD. Now, I hope it has not shorted out the electrical in the IP.

By the way, in the absence of the actual truck or burb, all we can is give you suggestion. So don't get frustrated with us. There is only so much we can do. The Startrek teleporter is still on its way until that happened we can only give suggestion.

I would not buy anything electronic from SSD, speaking from experience, all been replaced in less than a year of use.

check out the site vendors and pensacola diesel, and pmdcable.com for good deals. Might need to order from couple different places.

You should already have a high output water pump stock, the DMAX fan might help. Get the PCM reflash from Heath, or maybe Westers garage, not SSD. SSD's exhaust is a decent deal for stainless. If getting a turbo, Banks doesnt offer one better than the GM8 for our truck. The GM8 will do pretty good with 4" exhaust and a PCM tune. Get rid of that vacuum pump, dont repalce it, and just get a manual wastegate actuator. If you really want a different turbo there is the A Team Turbo, which wouldnt require a core return and no need for vacuum pump or manual wastegate actuator (it has no wastegate). Although with the A Team Turbo you might want that wife please muffler from SSD, its loud. One of the most needed reliabilty upgrades and for power is getting a better lift pump, Walbro FRB5 or Airdog or something, and for better throttle response help the fuel out by making all the fitting and lines 3/8" to the injection pump (requires modding the filter manager and some other fittings, also sold by walkingJdesigns)

No Heat sink. The pdm is just laying there, hooked to an extension cable, laying on the intake. Pure laziness, and the lack of a decent mentality to do it right. Musta been the dealership!:D

I'm also thinking I burned up the cable, and would be a lot happier if that was it!

Dealership would only charge you $3K to replace the whole IP with a PMD on it. Those bastards, never take it there or any mechanic really unless its a knowledgeble Stanadyne injection shop that rebuilds these IPs.

Now, its probable your new PMD did not come with a resistor in it, check inside the old PMD and fish it out of the connector and put it in the new PMD. OBD2 is a little finicky about that resistor.

I have actually had good luck with SSD. i have their pmd heat sync, new pmd, and IP(reman). the pmd has been on four years and has about 60K on it, but is also mounted under the front bumber. i think that it is pretty good luck with electonics being that i live in south texas and see heat well over 100 degrees for four or five months out of the year.

Would the truck started with or without the resistor? What if the new one didn't come with it and was installed without the resistor? I'm not at home to look, but this would have been something I overlooked.... again, this is my first diesel. :) BTW I didn't get critical about advice, I got critical about criticism...... but. we're past that now :) I'm pulling the intake in the morning to check over all of the wiring harness. I took it to the dealer shortly after I got back from Ohio. They said that a IP code came up and that it had a bit of an intake leak. So, I have to pull the intake anyway and reinstall with new gaskets. They also said that they wanted $2300 to replace the IP. I asked them if they also sold the crack they were smoking! For some reason they didn't find that nearly as funny as I did. :( F 'em I don't like dealerships anyway. I live in a very small town in Tennessee and I wasn't quite sure where to take it to have it looked at. I do now. We have two shops about 30 miles away. One is Dixie Diesel, and the other is called Beans Diesel Services. Um Dixie Diesel would be my choice. I have a hard time trustin a place called "Beans".

& Your right 1500, I checked into it, and I already do have the HO Water Pump, but it's completely covered in rust. With the heat on these motors, and the trips I like to take, I would just feel better replacing it. We're going to be pulling a 32' camper with it, and I would feel safer. Especially after this fiasco! Damn, maybe I should have gotten that 03 F350 7.3 powerstroke! With the amount of money I'll have into this, I could have bought one. LOL What did I just step into?!

I like the exhaust with SSDiesel, complete 4" with a 3" downtube. A1 customs has a bumper mount with an isolator plate. Which is better?

A1 customs has a bumper mount PMD with an isolator plate. Which is better? Isolator or heat sync

The heatsink in the bumper is good.

SSD heatsink is nice, and the PMD I got is still going, but thats because its a D-Tech from Flight Systems. They also have outrageous shipping charges. Just dont get the "HD" OPS or LP, the IPs can be found for less than $500 elsewhere with no core returns and the same PMDs for less that $200. Their tunes are made by someone else, so why order it through them and not the source? SSD has some things that other people dont carry though. If youre getting a new water pump I would recommend you get the one for the 2000, if you have the 96-99 one. And get it with the spin on fan. that is what comes with the Heath kit, but costs twice as much.

isn't A1 customs and steacksauce the same ?

Don't buy from A1 or Edam at the bay. They are known for shoddy reputation. You can search the word "Steaksauce".

PMDCable is probably the best bet for cable and heatsink.

FYI: people can call it isolator or anything but generically it is called heatsink. It functions the same as the heatsink attached to CPU in our computer.

Whats with all the "Dtech vs. Stanadyne" stuff, and dtech not meeting GM standards? I pulled the intake and the wiring is fried. So this is most likely a PMD issue and not one with the pump? Or could this have fried my pump too? I discovered that the "ip test" about the fuel bowl filling was wrong. This just tells you the lift pump is working right. How can you tell for sure if the IP is bad?

Dtech is actually better than Stanadyne but no electronics can withstand 200F. So you fried both the PMD itself and the cable. The cable was not part of the PMD, it was part of the IP.

Well, as I said, it is tricky, most of the time the PMD is the culprit. So you need a new one which you already have. I am still not sure on the year of your truck. SO TIME TO UPDATE YOUR SIGNATURE!!! Please.

I am sorry, this is a 1999 GMC Suburban 4x4...... Could someone also explain why this is listed as a 1500, but everything under it (suspension and axles) says 2500 - 3/4 ton. Even the title lists it as a 1500, 1500 on the doors, but 8 lug axles and HD suspension.

Thanks again

This was stated in my second post on this thread!!

Anyway, there it is, just for you JMJ, lol :D

So does that mean that I definitely have to replace the IP? How do you test the IP to be sure? I mean without having to put everything back together just to find out I have to rip it all back apart again?

I wouldnt expect your IP to be bad, but with the intake off you might be able to just replace the harness. There is one wire that goes to the fuel solenoid you can replace. Just need to remove the boot to the IP. That goes to the PMD.

I know that Tedreminder on here was selling the whole IP wiring harness, check out the classifieds or PM him.

Did you check for the resistor in the PMD?

Ya you were right, there. The old pmd had a #6 resistor in it. The new one didn't have one in it. Dumb mistake? Maybe. Anyway, would the lack of the resistor kept it from starting?

As far as I know, or what I was told, the resistor is only to fine tune the PMD. The FAQ has a bunch of info about it. It would run but it might not run as nicely. Also the PMD should, IMO, go to the bumper. The IP pulls fuel into the filter bowl no matter what, however this is a less than ideal situation. If you can, test fuel line pressure a normal lipft pump should be around 4-5 psi if I remeber correctly. Once its running again then it will be easier to pinpoint stuff. Good luck, may the diesel gods smile upon you.

Well, when I looked into the connector port for the old pmd there is a tan plate in there with a 6 and a line under it. I would assume thats a #6 resistor

The old resistor may not be correct for the new PMD. They are based on how much power the PMD puts out. Because transistors like the ones in a PMD are difficult to fine tune the resistor is used. Hope that helps

What really got me today was, i spoke to Dixie Diesel today and they told me that remote mounting the pmd was a bad idea. They told me that it's mount on the IP was actually the coolest spot. This goes completely against everything that I have read. I did see one post on one site that said the same thing, but everyone else says differently. This is getting confusing as hell. They said that if I had them fix this and remote mount the pmd, that they would not warranty the pmd or pump with it set up that way. GEEZ!!!!!!!!!

Ya it does. Would it bother anything, or would I have to make any other adjustments to the truck if I went to a #9?

They said that because that is the way GM designed it. If the PMD is left in the engine bay it is subject to heat. The issue with the PMD lies not necissarily when the engine is running but when it stops. The PMD is cooled by the fuel passing through the Injector Pump. When the egine is turned off the fuel, as cooling is also. If you heatsink it in the bumper that is the best way. PERIOD. If you have an issue with the IP or the PMD in the future just bolt it back to the IP and tell them to fix it cuz it broke. Just what I would do.

Better to be judged by 12 than carried by 6!

Just saw Streets of Blood myself

You would have to check the FAQ section on the forums for a total breakdown on the fuel rates based on resistor in the PMD, but no its the equivalent to almost nothing. You will notice no real power gains if you go to a #9.

Ya ..... LOL I like that. I also think I'm going to start carrying a frickin pmd, ip, gaskets, and tools in the bcak of the dan thing just in case this ever happens again 400 miles from home

The IP wont break frequently as long as the OPS and Lift pump are working correctly. I think an extra PMD wouldn't be a bad idea but if you remote mount it, failure is not as common. The OPS and Lift Pump as well as the fuel tank filter sock are things to keep a watchfull eye on. IMHO those are the most failure prone areas of the truck. I myself am ordering a 6 foot PMD harness and heatsink from PMDcable.com. I am also going to replace the OPS and Lift pump, as well as remove the fuel tank sock and put an in line filter and water seperator before the LP. Justt things to think about. And be glad you didnt get the 7.3 powerstroke. these issues would be twice as much to fix. My friend has a 96 7.3 and has had some expensive issues.

IPs wont just give up on you if you lube the fuel and run a good PMD, and good fuel supply pressure from the lift pump.

get that resistor out, make sure its not burnt, and put it in the new PMD, it doesnt matter what resistor you use. A #9 would provide 3mm3 more fuel. Stock L56 PCM programming requests 56mm3 max. The resistor accounts for differences in IPs, not PMDs, when flow tested on the bench the resistor calibrates the PCM inject signal output to match the desired fuel rate. So if the IP were perfect and just used a #4 resistor for no adjustment, and you put in a #9, then it would fool your PCM into sending the IP the inject signal for 61mm3 fuel rate. In OBD2 it could cause starting issues with no resistor, and you might not get a good connection without it there.

The pump is not even close to the best place for the PMD. I have mine on the intake, seeing how long it lasts there. I have thermocouples on each place and record 20C higher on the IP than even on top of intake. the pump doesnt get hotter after shutdown on mine and it never goes over the spec limit of the PMD. Its just that the internal components have thermocycling issues, not heat soak issues. The internal component fail from going cold to hot, hot to cold, cold to hot. So cold regions may fail even more, and anywhere with extreme temp variation.

The resistor accounts for differences in IPs, not PMDs, when flow tested on the bench the resistor calibrates the PCM inject signal output to match the desired fuel rate.

Yea I my bad, long day I mis informed. The PMD however should be mounted somewhere other than the engine bay. I can see why GM and Detroit put them there, but its not a good spot. In my opinion and the opinion of 90% of the people on here remote mounts in the bumper, or somewhere outside of the engine bay, for PMD on a heat sync are the best. second best is stock mounting on the pump, and a close third is the intake/heat sync on the intake manifold. I can't see exactly why a heatsync in a 150-200 degree engine bay would work well. If you have it outside in the bumper on a heat sync the ambient temperature would cool it more than on the intake heat sync.

I realize we are starting the PMD mounting war of the ages here so I will just say this, Brodas3, the FAQ located here http://www.dieselplace.com/forum/showthread.php?t=53309 will help. There is a section about PMDs about half way down. Make your own decision about it based on the info there.

The info about the IP being better than the intake is wrong according to the last 4 months of data I have seen from the thermocouple readings on my instrument cluster, but that is not the point, and I never said to mount it on the intake. Again, its not heat that kills the PMDs, it is thermocycles, so yes anywhere in the engine bay is worse than out of it.

I already recommended he get an extension cable and mount it in the bumper.

Where do you have the thermo couples mounted on your IP? If you don't mind me asking.

Where do you have the thermo couples mounted on your IP? If you don't mind me asking.

I still agree out of the engine bay is better, but heres what I have
I secured the thermisters with aluminum tape. Youll notice there is no PMD on the IP, and yes it still reports 20C over the heatinsk temp on the intake with the PMD running on it. Driving with AC on in the desert with insane temps in traffic I saw temps go up to almost 80C, which is almost 180F on the heatsink. The PMD may be a little warmer, but the IP surface was at least 10C warmer at that time. Normally I see Heatink around 40C and IP around 60C. I have verified temps with infared too.
9139991400
9140191402

Someone reccommended replacing the PMD harness, and although this may be the case, throw an ohmeter on it and see if any of the wires are actually damaged. You definitely should buy a longer harness, but rather than wait to find out that it might not be the prob, you can at least least get started troubleshooting.

My next piece of advice is to buy a SERVICE MANUAL! Not a hayne's, not a chilton's, but a factory service manual. The manual for my '98 has four phonebook sized volumes, and they break the instructions down to the point where a monkey could troubleshoot and repair your truck. You can pick 'em up off ebay for around $100 +/- 20 bucks. Good luck!