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Thread: skipping on deceleration?

  1. #21
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    Apr 2001
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    Quote Originally Posted by trbankii View Post
    "In theory, there is no difference between theory and practice. But, in practice, there is." - Jan L. A. van de Snepscheut



    So, as mentioned, a certain number of people carry a spare PMD. Should they be going through and replacing the switches, sensors, connectors, and such? And, if those are the actual problem, why does a new PMD rectify the situation - at least for some period of time?
    Fault tolerance: Durability.

    I think the underlying cause(s) are rarely identified, let alone corrected. A more "durable" component will often continue under the same conditions while a less durable component will fail earlier. Stanadyne's (and most other's) solution, albeit hardly a solution, wasn't/isn't to correct causal conditions, and it shouldn't be. Stanadyne answered GM's requirements. The system was designed and tested in a laboratory environment (to include prototype and test vehicles). The system was then applied to a flawed practical environment, and left to the random environmental affects of the public consumer. The two systems (the fuel injection system, and the vehicle chassis), are incompatible in practice, but it worked often enough to be called a success and marketed to the consumer. Bean counters caused the problem. Bean counters continue the problem. It is us diehard fanboys who tolerate their ineptitude.

    Should all the (supposed) causal components be replaced or upgraded? I dunno. How are we to know which components, even when new, are marginal in performance, and how many and which of the system components need to be marginal before we create the perfect storm that leads to inevitable failure?
    1985 Blazer 6.2
    2001 GMC 2500HD D/A
    dmaxmaverick@thedieselpage.com

  2. #22
    Join Date
    Mar 2000
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    Quote Originally Posted by DmaxMaverick View Post
    Bean counters caused the problem. Bean counters continue the problem.
    I've often hear that engineers should be required to use the products they design - the same should apply to bean counters by a factor of ten…

    Many thanks for the input. It gives me a better understanding of the situation.
    '94 GMC 6.5TD K1500 4L80E 2-Door Yukon SLE 221K
    '93 Chevrolet 6.5TD K2500HD NV4500 Std. Cab Longbed 187K
    '85 Toyota 22R RN60 4x4 Std. Cab Shortbed 178K (Currently retired for rebuild)
    Diesel Page Member #2423

  3. #23
    Join Date
    Apr 2001
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    Newberg Oregon
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    I bought a brand new GMC 3500 DUALLY 4X4 in 1994.

    Did not even get it home and it quit with all the indications we usually see with a dead/dying PMD

    The ign. switch, connections, grounds and such were likely not the issue that could possibly show up on a rig with a few years under its belt.

    We bought a new Burb 4x4 in 95 and it had the same problems.

    5 pumps later under warranty we offed the beast....

    I agree that in a perfect world (Test lab with unreal conditions) the system works..

    Not out in the real world with BUBBA at the helm.

    I suspect that voltage variability due to ????? Possible ground issues and gawd knows what else causes unnecessary stress on sketchy components that can't take the abuse and die.

    A diode in the alternator that's causing a slightly hinky current.
    A faulty plug pass through in the firewall.
    A ground bus connection deep under the dash that has one wire that is not making a good connection.
    A chassis ground cable that's not gittenerdone.
    A very small short/fault in the transmission electronic solenoids.
    NO WAY TO FIND THIS STUFF

    Trying to wring out any of these subtle anomalies is nearly impossible considering all the components/wires...yada yada yada involved in the entire electrical system of these rigs.


    Using components in the PMD that were a LOT more ROBUST likely would have cost a couple $$$ more per unit, but would live and shrug off slight issues with no worries.
    During the Reverse engineering process it should have been possible to see what components were failing and then figure out WHY and build around that problem.
    Build the thing hell for stout and forget the subtle issues of the real world..

    Our 95 Burb would run about 3K miles and the PMD would die.

    Clockwork... every 3K a fresh pump under warranty and good to go.

    Once were were getting close to 3K mark we would not take the rig out of town.

    Pretty soon ya had to drag it home from the grocery store.

    A fresh pump and good to go.

    Dealer made a million excuses and even accused us of NOT KNOWING HOW TO DRIVE A DIESEL VEHICLE

    Once I joined this Forum back in 01 I think, and learned a few things we bought another 6.5 and by then the aftermarket was alive and on the ball.

    Stanadyne does not have my respect AT ALL....

    GM knew they had a mess on their hands and simply tried to sweep it under the rug.

    LET THE FIELD SERVICE FOLKS DEAL WITH IT
    Last edited by Robyn; 06-09-2019 at 07:12.
    (1) 1995 Suburban 2500 4x4
    (1) 1997 Astro
    (1) 2005 Suburban (Papa Smurf)
    THIS IS BOW TIE COUNTRY

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