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Thread: 6.5 trouble shooting

  1. #1
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    Default 6.5 trouble shooting

    So I have a 95 k1500 that i recently picked up. I believe my pmd went out on me, my truck will run for about 10 minutes then it dies and if i go to idle the truck gets a nasty lope. Any other potential issues I might be missing?

  2. #2
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    Welcome aboard!

    It could be the PMD, but check the lift pump for operation and performance. It should provide steady 4-10 PSI at idle (measure with a gage connected to the fuel filter water drain --the T-valve located at the thermostat housing). Intermittent operation often suggests OPS (Oil Pressure Switch) failure.

    Being that it's a 1995 model, you can check lift pump performance without starting, or jumpering anything --- Set E-brake (and/or chock wheels), turn the key to ON, but don't start, move tranny shifter out of P, but not to N, turn key to Start. It should not start, but the lift pump should run as long as the key is held at Start.
    1985 Blazer 6.2
    2001 GMC 2500HD D/A
    dmaxmaverick@thedieselpage.com

  3. #3
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    The only reason I feel its not the lift pump is because it will start and drive. But just about when it gets to operating temp itll lose all power and die. but it doesnt throw any codes

  4. #4
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    When it dies, try throwing cold water on the PMD. If it then restarts the PMD is the prime suspect.

    If you have a scanner program, sometimes, when the PMD starts to fail, you can observe solenoid closure time start to fluctuate right before the "stall".
    The Constitution needs to be re-read, not re-written!

    If you can't handle Dr. Seuss, how will you handle real life?

    Current oil burners: MB GLK250 BlueTEC, John Deere X758
    New ride: MB GLS450 - most stately
    Gone but not forgotten: '87 F350 7.3, '93 C2500 6.5, '95 K2500 6.5, '06 K2500HD 6.6, '90 MB 350SDL, Kubota 7510

  5. #5
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    I am with Maverick

    Check the lift pump with the tranny in drive...ENGINE OFF and hold key in the crank position..
    Starter will not (Should not) operate, but the lift pump should.

    Make sure there is fuel available at the drain up front.

    Stick the hose in a can and operate the lift pump..

    You should get a nice flow of fuel.

    WHEN was the filter last changed ?????


    If the fuel flow is sketchy then the pump is suspect.
    Or as Maverick mentioned the oil pressure switch is/has gone south.

    With the engine running try opening the fuel drain.....if fuel flows this is good..

    If the engine stalls then the lift pump is faulty.

    A weird stalling is always a time to suspect the PMD... but due to the $$$$ its good to wring out the other possibilities first...

    Check the filter and the lift pump....if no issues found then suspect the PMD.


    The IP has a transfer pump inside, and it will pull fuel, but it's not what its meant to do and once things warm up and the engine idles down the transfer pump will/can fail to deliver enough fuel, resulting in a stall. (The lift pump is required to deliver a steady flow of fuel as Maverick mentioned.

    A failing PMD will in many cases cause a stall and no restart until it cools...worst case is a stall and no restart at all...
    (1) 1995 Suburban 2500 4x4
    (1) 1997 Astro
    (1) 2005 Suburban (Papa Smurf)
    THIS IS BOW TIE COUNTRY

  6. #6
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    A few years ago I had a similar problem with my 1995 6.5. It would start and run for a while and when I would be driving it the engine would shut down. There were no codes but after 5 or 10 minutes it would restart and be fine for the rest of the day. I did notice that when it would shut down the glow plug lite would not come on. After a while, the glow plug lite would come on and the engine would start again. This went on for a few months and then it would not start at all. After going thru the manual I saw where the glow plug controller has to send a signal to the computer in order to get the engine to run. I changed the glow plug controller the problem went away. After taking the glow plug controller apart, the contacts were in very bad shape.
    1995 Chev 4X4 1500 Suburban 6.5 TD,Phazer Gear Kit from JK, High Capacity Water Pump Kit from JK. Special Calibration fan clutch W/8 blade fan from JK
    1995 Chev 4X4 2500 Suburban 6.5 TD>>SOL-D (parts car)
    1999 Chev 4X4 2500 Suburban 454 "Gas Hog" with Hiniker C-Plow

  7. #7
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    Well, it's not the PMD. I ordered a new one and installed it today. Same thing happened on my way to work. I will test the lift pump when I get home. But at least now I have an extra PMD if I ever need it.

  8. #8
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    Is your fuel tank venting correctly?
    The Constitution needs to be re-read, not re-written!

    If you can't handle Dr. Seuss, how will you handle real life?

    Current oil burners: MB GLK250 BlueTEC, John Deere X758
    New ride: MB GLS450 - most stately
    Gone but not forgotten: '87 F350 7.3, '93 C2500 6.5, '95 K2500 6.5, '06 K2500HD 6.6, '90 MB 350SDL, Kubota 7510

  9. #9
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    Quote Originally Posted by tim s View Post
    Well, it's not the PMD. I ordered a new one and installed it today. Same thing happened on my way to work. I will test the lift pump when I get home. But at least now I have an extra PMD if I ever need it.
    That's good because you will need it.Not if but when!
    90 Chev 3500 c/c 4x4,6.2na,400 auto,4:10 gears.DSG Timing gears,main girdle, isspro tach, pyro,boost,oil and trany temp.Dual Tstats, High volume peninsular pump,on shelf, Custom turbo and intercooler 85%complete. Change of plans for the dually, it's going to get a Cummins. Both trucks are Blue 90 4x4 crews

  10. #10
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    The PMD is considered "A consumable" with these things..

    Like oil and filters, air filters...etc....WELL maybe not that often, but they are an item you should carry in the glove box....and tools to swap it.
    (1) 1995 Suburban 2500 4x4
    (1) 1997 Astro
    (1) 2005 Suburban (Papa Smurf)
    THIS IS BOW TIE COUNTRY

  11. #11
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