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I decided to post a thread after reading about this thread http://www.dieselplace.com/forum/showthread.php?t=42248

I have a 1997 Chevy Silverado Dully 3500 6.5 L Diesel truck and am trying to figure out which direction to go as far as fixing an issue I am having. Actually, this is a big issue! My wife was in a parking lot with the engine running and in drive when all of a sudden there was a lot of black smoke comming out of the engine and the tires were spinninh while she had the brakes applied. Apparently, the back end was swaying as the tires were spinning. She popped it in neutral and turned off the engine. After letting it set for about 5 minutes, she started the truck and drove back home. The truck would only engage up to the second gear and she was not able to go faster than 25 to 30 mph. The code that appeared was PO219 or fast throotle. The computer took on a safety mode and is why the tranny was locked into second gear.

I test drove it a few days later and it drove fine. The transmission was fine and all was working well. Before that, however, when I would drive it i noticed that every once in a while, there would be an extra burst of power almost like there was super charged gas going through to the pistons. This would not be too frequent rather 7 to 8 times per week. I would notice while at a traffic light mostly.

I took it in to get an analysis and the mechanic said it need a new fuel injection pump. I figured that after speaking with Bill Heath with Heath Diesel dot com and a repair facility that only repairs fuel injection systems. The prior owner of the truck installed the PDM away from the pump, on the side of the engine compartment above the front wheel well with its own fan to keep it cool, so I don't think the PDM is the issue, although it might be. I have in the past 12 months high pressure sprayed the engine to keep it clean and some water may have gotten in the PDM. Not sure, just a thought.

I am sure the majority will say to replace the fuel injection system, but having limited funds, I would rather approach this analytically. Realizing that there are several parts that make up the fuel injection system, i would rather seek a logical explanation to why the truck ranaway as other threads use that terminology.

The part # for the pump is either DS4831-5288 or 5521. Not sure since I have not physically seen the pump. I do not think it would be the shut off solenoid nor the PDM nor the cold advance solenoid since it creates stalls, which is not my case. Could it be the fuel transfer pump, the oil pressure switch or could it be again the PDM? Some insight would be great! If I could replace one part vs $1,700 for a new part plus install, then that would be ideal. Thanks for the time on reading and responding.
 

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You are not going to get much responce in the performance section, maybe the mods can move it, but it sounds like a PMD issue, I bought a new PMD that did that, I exchanged it and that one did the same thing, I found out that the flight systems ( diapco, Dorman etc...) were having issues so I got a Stanadyne PMD and has worked since, have you changed the PMD or IP lately? The PMD on the side of the pump is bad it needs to be moved to the bumper, look at pmdcable.com or heath for an extension harness and new PMD, I would try a good known working PMD first, and then keep a spare in the glove box!
 

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Check the name on the pmd, if it is anything other than stanadyne, such as flight systems, then I would start there, fs had a bad batch of pmds that when they failed they would go into full throttle mode. Already had it on my truck, bought a new pmd and an extension harness and mounted it to my front bumper. Haven't had a problem since then.
 

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Discussion Starter #4 (Edited)
Just checked out the PMD. It is a Dtech made in the USA. Could this be the issue? It is mounted on the far right hand sideabove the front tire well and has a fan attached to an aluminum heat dispensing metal bar. It seems to be in a good location although not on the front bumper. Would you recommend a Stanadyne or is Dtech a better unit?

Apparently, Dtech hired Flight Systems to manufacture these PMDs. Based on what you have said, the DTech (FS) may be the issue.

Aside from the PMD, what other issues may cause runaway acceleration? It does sound like a computer issue vs a hardware issue. Thanks!
 

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I would still mount it in the bumper, and yes Dtech is a flight systems PMD, look at a kit that comes with the PMD, cooler and extension harness( not from ebay) find a reputable seller, Heath or pmdcable or Kennedy diesel as mentioned before.
 

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I would still mount it in the bumper, and yes Dtech is a flight systems PMD, look at a kit that comes with the PMD, cooler and extension harness( not from ebay) find a reputable seller, Heath or pmdcable or Kennedy diesel as mentioned before.
Thanks for the insight! I will order a new PMD and will keep you posted on the outcome. Once installed, I should know within a weeks time if it is working correctly. I will re-run it to the front pumper or around that area.
 

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The PMD is the only logical explanation for those symptoms. How its supposed to work. PCM receives input from 3 sensors in the fuel pedal. If any one of them is actiing up the other two check it and cancel it out and you get a code for it. The PCM then looks up a fuel rate by pedal percentage and RPM and translates that into a pulse width to the PMD. The PMD takes that pulse width and spits it out in a higher voltage and current signal to the IP's fuel solenoid. The fuel solenoid reacts to the power by closing the metering valve which allows fuel to be pushed to the injector. Then the pulse goes away (to zero power) and the valve opens and repeats the process over and over.

The PMD is the middle man in the equation, and can often times go rogue. The PCM would control itself or any of its inputs and outputs.
 

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Discussion Starter #8
Interesting! Thus far the majority rule is the PMD. I say interesting because, Heathdiesel dot com says it's the Injection Pump and my mechanic says the same. I am hoping that a lot of people in my same situation can benefit from this thread. Will keep you all posted!
 

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Well, funny story, i was told the same thing when my truck acted, same as many people here have, but I decided to just try the pmd for shits and giggles because the IP on mine had less than 5k on it. And if it was the IP you would have zero control over it at all. When the armature shaft (iirc) breaks you basically have 2 pedal positions if your lucky, off or full throttle... I highly recommend replacing the pmd for starters and moving it to the bumper. I bolted mine to one of the valance holes in the bottom flange of the bumper and drilled a second hole for the other bolt.
 

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I thought D-Tech was supposed to be the best available? With heat soak and all... So stanadine(?) is the best choice?
 

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I thought D-Tech was supposed to be the best available? With heat soak and all... So stanadine(?) is the best choice?
d-dech is a rebadged flight systems pmd which is the most common to have the runaway when failing, stanadyne generally just dies when it fails but there have been a few reports of those as well having the sudden acceleration but are far far less common to do so.

bottom line is both stanadyne and flight sytems(which anything not labeled stanadyne is made by) both fail at any time, the stanadyne is the least likely to have the runaway happen but its something that every electric 6.5 owner should always be prepared for and if you are experiencing any random surging it is more probable it will die on you soon.
 

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Well that sucks. And false advertising too.
 

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Technically, if you get one of these Flight Systems PMDs you can get a free replacement. Just give them the serial number and I think they even published a range of serial numbers that are suspect and can be replaced outright.

And since then they have done work to address the issue, so that their latest model is likely the best PMD available. Their competition also pushed Stanadyne to actually try to address the common failure item. And drove the price down, so wouldnt crucify them just yet.
 

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Well that sucks. And false advertising too.
What do you mean false advertising thier name is " Flight Syatems" they tell you in the name they will run away!:D
 

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I thought D-Tech was supposed to be the best available? With heat soak and all... So stanadine(?) is the best choice?
IMO, for now I am still using Stanadyne.

No PMD can withstand heat soak not DTech/FS nor Stanadyne.
Anywhere inside the hood, it is bad.
Heat does not have mind, I wish they do.
Oh, "the PMD is on the fender with a fan, so that area is restricted".

We as human, sometimes think heat has mind.
So they started putting a fan, etc.
LOL!!!
 

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My Dtech has lived happily on the intake for more than 4 years now. So it can withstand high temps. I had two thermistors installed, one on PMD heatsink at base of PMD and another on the IP where PMD used to be installed.

The PMD heatsink would usually be around 130F, up to as high as 150F sometimes. My DMax fan that pushes more air without clutch engagement may have been keeping the whole intake cooler than stock fans. The IP was always about 20F higher under the intake.
 

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My Dtech has lived happily on the intake for more than 4 years now. So it can withstand high temps. I had two thermistors installed, one on PMD heatsink at base of PMD and another on the IP where PMD used to be installed.

The PMD heatsink would usually be around 130F, up to as high as 150F sometimes. My DMax fan that pushes more air without clutch engagement may have been keeping the whole intake cooler than stock fans. The IP was always about 20F higher under the intake.
you were lucky it lasted that long
its not temps while running that is the issue, its heat soak after the engine is shut down that kills them, your fan pushes no more air than the 97+ fans, its just plastic vs the steel, same diameter and blade count
 

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My Dtech has lived happily on the intake for more than 4 years now. So it can withstand high temps. I had two thermistors installed, one on PMD heatsink at base of PMD and another on the IP where PMD used to be installed.

The PMD heatsink would usually be around 130F, up to as high as 150F sometimes. My DMax fan that pushes more air without clutch engagement may have been keeping the whole intake cooler than stock fans. The IP was always about 20F higher under the intake.
One thing you forgot to mention is that you live in California which has somewhat mild climate. No real freeze or real hot with a rather narrow range of temperature.

Try it in TX with temperature swing or even worst in AZ for the heat.

The Northern part of the country usually not too good either because it is freezing and hot with a wide range of temperature. PMD usually failed during that temperature swing in the spring or fall.

I have mine in the bumper for a couple of years now. The previous PMD lasted for 4 years in the bumper but that was a used one.
 

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I know why they fail, its just people always go back to heat being the issue, and its not really. I have driven it through death valley, and Nevada, to Las Vegas several times. In general though, yes I live in temperate climate, and thats where its operated the most.

And yes, the DMax fan does pull more air than a stock 97+ steel fan. Its about the blade pitch and surface area, and design.

And you know what, I have monitored the temps after shutdown, never skyrocketed, maybe a couple of degrees higher. I monitored the PMD temps for over a year, on a battery operated unit so it was at all times, cold, hot, running or not.
 
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