98 c2500 starts but shuts down from 5 to 15 seconds

Discussion in 'Chevy Truck Forum' started by dannyboy950, Feb 20, 2011.

  1. dannyboy950

    dannyboy950 Full Member

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    I have been fighting this truck for awhile now. All fuses good all relays good.
    problem started with fuel pump going out replaced pump tried to start and would shut down

    Scanned with Genisys 3 found no relevent codes and live data seems within specs. Tested all sensors both on and off truck all operate within ranges. Changed the following sensors,TPS; ignition module; rotor.
    Running various tests have determined fuel pressure is good and does not drop off before shut down. I have power to plugs right up until shut down this would eliminate ignition system.
    Truck has passed all self tests the Genysis is capable of. Really running me nuts now.
    Swallowed my pride and called the checy dealer they thought the security system was locking me out. Did the key relearn three times with no luck. I had changed out the key lock before but truck had run fine for four months.

    The truck is hard to startand acts like it is slightly out of time but will crank and run. If it was a diesel I would say it was haveing trouble syncing the cam and crank signals.
    Thinking along those lines the truck had had a power steering leak soaking everything. I am beginning to wonder if the rubber has become softened and the harmonic balancer may have turned on the bonding ring a few degrees.
    Either that or the passlock module has died.

    Any ideas appreciated. I may be an old dog, over 40 years experience but always willing to learn new tricks and diesels are my main skill.

    Thanks for any ideas.
     
  2. chevychase

    chevychase Semi-Admin
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    Reckon all that steering fluid .... has messed up crank sensor??
    Also make sure dist hold down has not worked loose.
     
  3. dannyboy950

    dannyboy950 Full Member

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    Thanks for that thought, I removed and cleaned the sensor and tested it but no joy. Distrib.hold down is tight. Good ideas tho. Any idea how common a passlock failure is?
     
  4. chevychase

    chevychase Semi-Admin
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  5. dannyboy950

    dannyboy950 Full Member

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    I checked fuel pressure and actually replaced the press regulator. This leads to a question, I have the CSI injection system and according to one of the manuals it says it is vacum activated and one manual says it is not. Which is correct. When I pulled the intake and removed the old regulator there was no vacum line on the regulator.
    Since the pressure iis read downstream of the regulator you will show full pressure but not necessarily be getting it to the injectors. This may be my actual problem.

    By the way the link does not work for me but thanks for the address it will prove usefull.
     
  6. chevychase

    chevychase Semi-Admin
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    Just click on link should work now ... good info.
     
  7. leolkfrm

    leolkfrm Full Member

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    when you did the passlock relearn, did you wait at least 10 min or the light blinked? did you have a battery charger on it? voltage drop will not let it relearn, some systems need a back to back 3 time relearn to set the system, there is also a way to bypass the system with a resister....a quick web search will give you a method for your vehicle.
    you may try a local alarm installer, I have one here that works wonders on bypassing the factory stuff
     
  8. dannyboy950

    dannyboy950 Full Member

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    Thanks for the exellent ideas. The passlock is no longer showing the system to be locked,so I am gonna repull the intake and look for a vacume hose connection for the regulator.
    There wan't one when I changed the regulator but the hose may have deteriorated, there was a lot of crud that I vacumed out when I was in there.
    Thanks a bunch.
     
  9. JHR1983

    JHR1983 New Member

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    i had a similar problem on my 97 z71. It ended up being my fuel pump relay. It would fire up and run for a sec then die. I pulled the relay and it had a melted spot on one the prongs. I replaced it and it ran fine. U can buy one at any parts store for like 15 bucks. Maybe it will help. Its in the black box on the driver side under the hood.
     
  10. JHR1983

    JHR1983 New Member

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    oh and also i bought a new fuel pump from autozone and it was faulty. It would start up and run for a sec then die. But it would start right back up and run a few secs and die again. I replaced it with an advanced one and it runs fine now.
     

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