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Thread: 98 GMC Suburban Revival

  1. #1
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    Default 98 GMC Suburban Revival

    Hi All
    I need a road trip vehicle for a spring road trip which will include visiting a friend that has a 100+ kilometer unmaintained driveway.
    So i chose the diesel Suburban that had been left behind by the PO,with plans to retrieve at a later date.I had given him a pickup in trade,that he was supposed to return in similar shape.He passed away and his family did not want to retrieve the Suburban.
    I did a quick assessment when i cleaned out a pickup load of cloths from it a couple years ago and got it running.
    The cat was plugged solid,i removed it and it ran.Brakes were gone so i did not drive it much.
    At the moment it needs complete brake job,alternator wasn't charging and running like crap.

    So i am looking for ideas on the crap running part.

    It's not throwing a code,but acting like it's still stuffed up.Lots of black smoke and no power.
    To get it running a few years ago i had to wire in the lift pump,relocated the PMD from the intake to in front of the left battery behind a hole in the rad support.
    Online last night got me a price of $1600.00 for master cyl,rear shoes,drums wheel cyl,seals,hardware,front rotors,pads,calipers and alternator.Delivery March 4th.Going to see what prices are like with my account local.
    I hope to get a few weeks driving before the road trip.
    Interior needs to come out for a good cleaning.
    Thanks for any insite and advice as i move forward.
    Thomas98 sub.jpg
    Attached Images Attached Images
    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

  2. #2
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    Default

    A few more pic's
    can't remove the triple pic from the last post.Attachment 6443Attachment 6444Attachment 6445Going to change the regulator in the Alt and see if that fixes it,looks good inside.
    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

  3. #3
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    Well that didn't work...old computer
    Interior is stripped out,floor looks great for a 24 year old truck
    Going to pressure wash the carpet and try to get it looking close to one shade of grey
    Borrowed a good PMD from Sis in Law and got a new alternator as changing the regulator didn't fix the old one.No core on the new alt so i will continue to try and fix the original,it looks good inside.
    Have all new parts for the brake job,all from Napa came very close to online prices,exchanges will be a lot easier than mail if there is an issue.
    Hopefully the PMD solves the running issue,otherwise i will be looking for advice for hunting demons.98 sub h.jpg98 sub i.jpg
    Attached Images Attached Images
    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

  4. #4
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    So a known good PMD did not solve the issue
    Background...
    A couple years ago i did an initial look at the Sub.
    I found the fuel pump wiring messed up,the PMD was mounted to the intake and the big one the Cat was plugged solid.
    I fixed the issues moved the pmd and removed the Cat.The brakes were totaly gone so i did not drive it other than around my yard,and parked it.
    Fast forward to last week
    I put a couple battery's in it and it fires right up.
    It had settled into the dirt a bit so it was like trying to drive over a 2x4 in front of each wheel.
    As i gave to throttle it started to surge and it was blowing black smoke like crazy,eventually i got it rocked out of it's holes and drove it around the yard lots of black smoke and surging,got it into my shop and now am stumped.
    Borrowed a PMD from SIL that is a known good one after trying an extra i had,removing the extension cable to the remote mount and hooking back to the factory cable and intake mount the running issues didn't change other than it will not start now,actually it will fire but die as soon as you release the key.If you keep the key in the crank position it will fire and die while cranking.If you keep cranking for an extended time it will try to fire again but not quite as long as the initial fire from a cranking event you just start.
    Fuel pump is working
    Any help will be appreciated.
    Thanks Thomas
    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

  5. #5
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    Have you checked the intake and filter box for uninvited guests or remnants of their housing?
    "The Constitution is not an instrument for the government to restrain the people, it is an instrument for the people to restrain the government."
    -Patrick Henry


    A5150nut
    2006 K3500 D/A
    94 6.5 4x4 5spd Sold

  6. #6
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    Black smoke = too little air, for whatever reason. As said, perhaps uninvited guests in the plumbing. Or, the WG is stuck open, or not being pulled closed (vacuum or WG control issue). An improperly grounded PMD harness can cause surging/missing. The ground from the harness MUST be connected to the pump housing. The surging could also be caused by air in the system (and cause a no-start, once air-locked). Attach a looped, clear line to the filter outlet and run the lift pump (into a container, of course). Any air intrusion should show itself.
    1985 Blazer 6.2
    2001 GMC 2500HD D/A
    dmaxmaverick@thedieselpage.com

  7. #7
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    I did check for the ground and it was conected
    I took the elbow from the air box off to verify the turbo wasn't seized.
    I checked the lift pump for operation,jumper-ed it to verify flow to filter and drain spigot.
    Yesterday was a very warm sunny day so i took advantage of that and pressure washed the carpets
    Day before i got the front brakes installed,bearing feel good.One hub had deformations on the face from some a previous repair.I filed it flat so the rotor would fit flush,makes me wonder if it had a pulsing pedal from those dents.A good chance the rotor would not be true to the hub.
    A couple shots of before and after the carpet wash,24year old carpet will still show some shades of discoloration but at least its clean and if i drop some food on it i will be confident on picking it up and eating it.
    sub carpet 2.jpgsub carpet.jpg
    Attached Images Attached Images
    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

  8. #8
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    Any codes showing SES ON ???
    (1) 1995 Suburban 2500 4x4
    (1) 1997 Astro
    (1) 2005 Suburban (Papa Smurf)
    THIS IS BOW TIE COUNTRY

  9. #9
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    It hasn't ran since i drove it into the garage,not that it was running great then.But it was running.
    My plan is to add a pressure gauge to the fuel system,make sure the ground is actually grounding on the pump for the PMD harness Those are next steps on the running department.
    When it was running a couple years ago it smoked bad,my theory was with the exhaust being plugged,and the PO driving it till it would die for days to try and get to our town.I think the injectors may have suffered some damage,from the back pressure of the exhaust being plugged.
    I tried to pull codes and there were none,the ses light is on but seeing it will not start i can't see if it stays on.
    Yesterday i cleaned up the mess that was the back brakes,black oily mess,all my tools are black that i was using.Got them pulled apart hubs pulled everything cleaned up for when the rest of my parts come in.
    I may get time to add the gauge today,if not tomorrow i have to deliver fuel so there will be no update for Monday.
    Thanks for all the help
    Thomas
    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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    I hooked a pressure gauge into the line with the drain spigot at the front of the engine,it showed around 8PSI before and during the start sequence where it fires and dies.
    The ground wire was tested to see if there was ground at the terminal.
    And pulled a couple codes
    P1626 Anti-theft system fuel enable CKT
    U1000 class 2 serial comm, problem
    These were found with a Snapon MT2500 "red brick"
    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

  11. #11
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    If it cranks, or tries to start then stalls, and you get the P1626, the BCM isn't receiving the correct signal from the ignition cylinder. Check fuses (primarily the IGN and Instrument/gage fuses). It could be a wrong or damaged key, ign. harness damage/connection issue, or a failed or incorrectly programmed BCM. If you have an original key, try clearing the DTC's and try again. The U1000 may indicate the signal is simply missing, which suggests an open or grounded signal circuit. If the PCM, BCM connections are good (remove/reconnect them), and the ign. connector is good and undamaged, try disconnecting both/all batteries and ground one of the Batt+ cables to ground for 30 minutes. Reconnect and try again. This system check can be bypassed entirely with a Tech II, but I don't know if you can do it with your MT2500.
    1985 Blazer 6.2
    2001 GMC 2500HD D/A
    dmaxmaverick@thedieselpage.com

  12. #12
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    I only have the one key for the truck,and it looks like an original key.It has the GM in the plastic and nothing to indicate it is a chipped key.
    With the Banks Power package,would it have come with a chip that is replaced in the computer?
    If it is an issue to do with missing chipped key,is there a workaround?
    Thanks for the help Dmax Maverick,computer issues are my kryptonite
    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

  13. #13
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    Early "chipped" keys had visible/physical chips, while the later ones are hidden (RFID, and still are). I don't know what years or models it applied or changed. Many of them had paired lock cylinders, that will only decode if the correct (cut) key is used, preventing "hotwiring", or a bypassed key cylinder. Again, I don't know what years/models applied, but it sounds like your 1998 is the latter.

    The Banks power package, if electronic, can certainly be a player. I'd start by removing it, and see where that gets you. 1998 models won't have a "chip", being OBD II. It may be reprogrammed, which should preempt the security. Look for a Banks plug-in module. If it has one, remove it, as it may be interfering with the ignition cycle. I don't recall how Banks added power, outside of upgraded turbo, intake, exhaust, and/or wastegate, and perhaps injectors. Later model (Duramax) Banks upgrades have inline programming modules. Any time a truck with a power adder has running issues, step-one is removing the device. Very often (especially with Edge modules), that cures the issue. The modules can be restored once the PCM gets itself straightened out (until the next time). If the PCM has been reprogrammed, it will have to be replaced or recalibrated, either with another aftermarket or OEM. However, while the PCM can be an issue with starting and the security protocol, it's almost always the BCM that's the cause (all else being healthy).
    Last edited by DmaxMaverick; 02-22-2022 at 14:06.
    1985 Blazer 6.2
    2001 GMC 2500HD D/A
    dmaxmaverick@thedieselpage.com

  14. #14
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    Ok today i had time to pull the PCM all connections look great,all the wiring looks stock and unmolested.No remote start or aftermarket security or stereo.
    Where is the BCM located?
    Hooked the ground and positive together once i had reinstalled the PCM.
    No change in it's behavior,turn key to on glow plugs cycle,fuel pump cycles engage starter once glow plug light stops,motor fires with a healthy rattle and dies immediately after the fire even if you hold the key in the starter engaged position.
    By the looks of the sticker something has been reprogrammed in the PCM.
    sub computer 2.jpgsub computer.jpg
    Would a PCM from a 96 2wd work to see if there is an issue in it?
    I haven't seen anything with Banks on it other than the muffler and the badge on the door,where might a plug in modual be hiding?
    Thanks Again
    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

  15. #15
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    A different PCM won't work, if the BCM isn't sending the ignition signal. That PCM has been reprogrammed. You can try another PCM. If it works, then it's likely the original (in your hand) has failed, or the reprogram is corrupt. I'd contact the supplier on the label and find out what you have. They may offer to reprogram it, or reprogram another, if it's corrupt.

    The BCM is located inside, on the firewall, near the column. It should have 3 different colored connectors.
    1985 Blazer 6.2
    2001 GMC 2500HD D/A
    dmaxmaverick@thedieselpage.com

  16. #16
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    Could it be as simple as a failed oil pressure switch?

    Bill
    91 Buick Roadmaster/Avant 6.2 NA conversion (gone but not forgotten)
    94 Cadillac Fleetwood (sold)
    08 Aerolight 23TT
    06 Vortec Max Silverado CC SB (sold)
    10 Avalanche (electronic quagmire but love the truck)

  17. #17
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    Quote Originally Posted by convert2diesel View Post
    Could it be as simple as a failed oil pressure switch?

    Bill
    Maybe but the fuel pressure is good throughout the brief start cycle.
    My guesstimate is maybe the ignition switch?
    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

  18. #18
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    Quote Originally Posted by DmaxMaverick View Post
    A different PCM won't work, if the BCM isn't sending the ignition signal. That PCM has been reprogrammed. You can try another PCM. If it works, then it's likely the original (in your hand) has failed, or the reprogram is corrupt. I'd contact the supplier on the label and find out what you have. They may offer to reprogram it, or reprogram another, if it's corrupt.

    The BCM is located inside, on the firewall, near the column. It should have 3 different colored connectors.

    Thanks again
    Have you ever seen the supplier that is on the decal? I am wondering if they maybe did programing for Banks?
    I will try and find some info on them.Plus check out the BCM
    In your response you mention a different PCM wouldn't work.Then to try a different PCM.Did you mean BCM instead for one of them?
    Thomas
    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

  19. #19
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    Trace out the power feed to the PMD and make sure you are getting 12 V or more to the PMD
    A failed ignition switch could cause the issue....but holding the key in the crank position should keep it running......

    Check the power to the fuel shut off solenoid on the IP (Silver round unit on top of the IP)
    This bad boy should activate and stay activated unless the power goes off OR THE UNIT IS FAULTY.

    Make sure the unit CLICKS when the key is turned to the on position......If not...check power.... Helper needed
    These are easy to replace.....DO NOT TRY TO RUN WITHOUT IT....

    See what shakes....let us know
    (1) 1995 Suburban 2500 4x4
    (1) 1997 Astro
    (1) 2005 Suburban (Papa Smurf)
    THIS IS BOW TIE COUNTRY

  20. #20
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    Quote Originally Posted by Yukon6.2 View Post
    ....In your response you mention a different PCM wouldn't work.Then to try a different PCM.Did you mean BCM instead for one of them?
    Thomas
    A different PCM wouldn't work, IF the BCM isn't sending the ignition signal. If the BCM is failed, or is failing to send the signal, for whatever reason, it won't matter which PCM you are using.

    Have you ever seen the supplier that is on the decal? I am wondering if they maybe did programing for Banks?
    I will try and find some info on them.Plus check out the BCM
    I'm not familiar. If Banks is selling it, especially as an upgrade kit, their name is on it, at least in part.

    Definitely check out the BCM.
    1985 Blazer 6.2
    2001 GMC 2500HD D/A
    dmaxmaverick@thedieselpage.com

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