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Thread: shuts down while driving, then starts right back up.

  1. #1
    Join Date
    May 2007
    Location
    Oxford ohio
    Posts
    52

    Default shuts down while driving, then starts right back up.

    Any ideas? In the past I have had a similiar issue and put a new harness from key switch on and it seemed to have solved problem (1 1/2 yrs ago.) But truck will start and run but especially going up hills or if I step on the pedal it hesitates and not always but more often now it shuts down. After coming to a stop it will restart and idle but usually have to limp it home. Trying to solve problem I just changed the fuel filter, but it really did not help the issue.

    1995 chev. 6.5 turbo diesel
    230 k - 100k on engine.
    1995 6.5, 3/4 ton, 2 wd, 5 speed, 227k, 90k on engine

  2. #2
    Join Date
    Feb 2007
    Location
    Baja California Sur Mexico
    Posts
    2,681

    Default

    Sounds like the fuel lift pump is not working.
    Grant H.
    1994 6.5 turbo GMC K2500 HD suburban "F" VIN FSD heat sync #9 resistor, PMD in the bumper, no cat, mechanical waste gate, 220,000 miles, 4L80E Positrac 3.73 diff, 17 mpg highway.
    1982 4x4 shortbed 6.2 Chev 260,000 miles untouched motor 17 MPG 4.27 diff. Best thing I ever owned, 21 years.

  3. #3
    Join Date
    May 2007
    Location
    Oxford ohio
    Posts
    52

    Default

    Where do I find the lift pump?, is it easy to replace? How much should I expect to spend if I do it myself? Thanks
    1995 6.5, 3/4 ton, 2 wd, 5 speed, 227k, 90k on engine

  4. #4
    Join Date
    Jul 2009
    Posts
    362

    Default We can fix that . . .

    Replace your lift pump, change out the fuel filter as well tho i think its part of the pump warranty requirements, other thing i would suggest is how old and where is your PMD located ?

    The Lift pump will be located right under your drivers side door on the inside of the frame rail it will look like a GM-Gasser's Fuel filter only it'll have wires coming out of it IIRC 1 wire is brown and the other wire is black but don't quote me . . .


    If you need or want i can post up a photo of the pump ?


    Mike
    1995 GMC K2500 "Turbine":
    6.5-T (F), 4L80E, 4.10 gears, LT7.50-16D tires, 140K miles.

    Mods/Upgrades:
    1. D-tech PMD #9 Resister bumper mounted.

    2. Air-box Deletion / Open air intake.

    3. CDR Deletion / Valve cover breather.

    4. Open exhaust.

    5. 3500HD trans cooler.

    6. Mechanical waste gate conversion.

    7. Gauges: Engine Oil temp, Boost, Trans temp.

    Mike

  5. #5
    Join Date
    Feb 2007
    Location
    Baja California Sur Mexico
    Posts
    2,681

    Default

    Most likely the oil pressure sensor that makes the pump run. I had it fail on the road and connected a wire from the fuse on the passeger side of the fire wall, behind the plasic cover, to a live wire in the wiper plug. Pump runs when the ignition is on, can stay like that, OPS system is only safety shut off of the lift pump in case of a wreck.
    Grant H.
    1994 6.5 turbo GMC K2500 HD suburban "F" VIN FSD heat sync #9 resistor, PMD in the bumper, no cat, mechanical waste gate, 220,000 miles, 4L80E Positrac 3.73 diff, 17 mpg highway.
    1982 4x4 shortbed 6.2 Chev 260,000 miles untouched motor 17 MPG 4.27 diff. Best thing I ever owned, 21 years.

  6. #6
    Join Date
    Jul 2009
    Posts
    362

    Default

    Yes this is true it can be bypassed i have mine on a high amp switch, tho i have found the truck will run several mile with out the LP running

    I forgot to fli it on one time i drove it a good 5 miles before i noticed it was off, So I'm guessing it'll run with out it ? ?

    Maybe it was fluke and i got lucky . . .


    Mike
    1995 GMC K2500 "Turbine":
    6.5-T (F), 4L80E, 4.10 gears, LT7.50-16D tires, 140K miles.

    Mods/Upgrades:
    1. D-tech PMD #9 Resister bumper mounted.

    2. Air-box Deletion / Open air intake.

    3. CDR Deletion / Valve cover breather.

    4. Open exhaust.

    5. 3500HD trans cooler.

    6. Mechanical waste gate conversion.

    7. Gauges: Engine Oil temp, Boost, Trans temp.

    Mike

  7. #7
    Join Date
    Feb 2007
    Location
    Baja California Sur Mexico
    Posts
    2,681

    Default

    If there are no air leaks in the system, it will run without a lift pump, mine did for a few hundred miles until I realized what was causing the hicup on hard acceleration.
    Grant H.
    1994 6.5 turbo GMC K2500 HD suburban "F" VIN FSD heat sync #9 resistor, PMD in the bumper, no cat, mechanical waste gate, 220,000 miles, 4L80E Positrac 3.73 diff, 17 mpg highway.
    1982 4x4 shortbed 6.2 Chev 260,000 miles untouched motor 17 MPG 4.27 diff. Best thing I ever owned, 21 years.

  8. #8
    Join Date
    Jul 2009
    Posts
    362

    Default

    Well then that must be good sign then

    Mike
    1995 GMC K2500 "Turbine":
    6.5-T (F), 4L80E, 4.10 gears, LT7.50-16D tires, 140K miles.

    Mods/Upgrades:
    1. D-tech PMD #9 Resister bumper mounted.

    2. Air-box Deletion / Open air intake.

    3. CDR Deletion / Valve cover breather.

    4. Open exhaust.

    5. 3500HD trans cooler.

    6. Mechanical waste gate conversion.

    7. Gauges: Engine Oil temp, Boost, Trans temp.

    Mike

  9. #9
    Join Date
    May 2007
    Location
    Oxford ohio
    Posts
    52

    Default

    Yes, thanks for the info on finding the lift pump. As I was reading the other posts, it reminded me that the truck runs for about five miles before the truck starts acting up. Is that an indication of lift pump failure?
    So I should: replace lift pump first.
    fuel filter was just replaced two days ago.
    *the pmd- thats the box mounted on the intake- its still in the original spot
    1995 6.5, 3/4 ton, 2 wd, 5 speed, 227k, 90k on engine

  10. #10
    Join Date
    Jul 2007
    Location
    Attica, OH
    Posts
    1,061

    Default

    did you ever replace the ops? The drive it a few miles then hiccup is what my truck did when the ops was dead. its a few $ cheaper too. I hot wired my lift pump ( had 12 volts to pump but bad ops contacts wouldnt let enough current thru it to operate lift pump)after replacing it and finding out the ops was junk. Wish id have seen that gm bullitin on that conditiuon before replacing the $80 lift pump.
    93 chevy K2500 6.5TD 4x4 4l80e auto
    Custom flatbed with foldaway gooseneck ball
    SSDiesel DB2 injector pump marine injectors
    Upgraded turbo ( no id tag but lots of boost)
    SSDiesel 4" exhaust, no muffler, SS crossover
    Rebuilt 4l80e tranny Transgo stage 2 shift kit
    rebuilt HD torque converter
    4x4 Posi Lock
    Opened up air box, stock filter
    Boost, Pyro, Tranny gauges in A-pillar
    Cowl hood, all new paint.
    SS Diesel Cooling upgrade, single tstat Dmax fan,
    '98 HO waterpump.

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