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Stumbling 6.0

Discussion in 'Chevy Trucks' started by mayhem, Sep 23, 2006.

  1. mayhem

    mayhem PlowSite.com Addict
    from Peru MA
    Messages: 1,016

    2000 Silverado LT 2500 x-cab with the 6.0 and 4 speed auto, 91k miles. Just bought it a couple weeks ago and I'm having some startup issues that I need to resolve. When I start the truck up it tends to stumble alot before it settles down to a smooth idle. Like the gauge lights flicker sometimes if I let it just sit by itself and it goes away if I give it some gas. Its acting almost as though its fuel or electrically starved. I swapped out the battery that was in there with one I put into my 85 2500 in April and the first time I started it it fired right up, no problem...but after driving it awhile (a number of 15 minute or less hops between places) it seems to be getting worse, not better. I read the voltage across the terminals and its a solid 12v off and 14v running. Is it possible that I have a bad alternator and the current is low even though the volts are there? Fouled plugs? Fuel filter? I've got no CEL, but have not pulled any codes to see if there are any stored codes.

    I bought a can of Chemtool B-12 to clean out the injectors and combustion chambers, but I'm looking for other suggestions too.

    Looks like the plugs are pretty deep inside the block, are they a PITA to change?

    I'll be in touch with the dealer of course as I have a 30 day warranty, but I'm interested in other opinions since the dealer is an hour's drive away from me and I'd rather not take it there if I can avoid it. The only thing I can think of is they gave it a really heavy cleaning when I picked it up, including wet washing the carpets and what looks like powerwashing the motor (which I had a bad experience with my SHO with)...the thing is cleaner than new under the hood.

    The more I think about this the more likely it seems that I've got original plugs and wires and they probably soaked them when they washed the motor. If they're original its probably time to change them anyway since they're supposed to be those 100k plugs IIRC. It seems to run a bit on the rough side after it catches too, but its been so long since I've had a V-8 that my memories of very smooth idles might be wrong...not missing any pistons mind you, but its not super-smooth either. Returning about 12.x mpg arouns town, 13.8 highway with an 8' fisher blade in the bed.

    Thanks in advance guys.
     
  2. JRKRACE

    JRKRACE Senior Member
    Messages: 172

    My gut tells me the washing may have done something. Good luck..
     
  3. mayhem

    mayhem PlowSite.com Addict
    from Peru MA
    Messages: 1,016

    Just put in a set of new Delco Iridiums and will be filling up tomorrow at my regular station...it ocurred to me this afternoon that I've only filled it twice so far and both times it was at the same station...one that I never go to since its really out of the way. I'll dump the Chemtool in when I tank up and hope for the best.
     
  4. scottL

    scottL PlowSite.com Addict
    Messages: 1,603

    Lucas for injector cleaner - gooood stuff!

    Flop out the cap/rotor. I was amazed when mine went. I couldn't believe how much this item affected everything else. Given they power washed your engine ( show-room-shine ) it is probably fowled if not simply old.

    Power washing could affect many things. Maybe even a bad ground. I'd shoot for the cap/rotor in any case. Check the codes - not all code readers will pick up the emission codes though.
     
  5. mayhem

    mayhem PlowSite.com Addict
    from Peru MA
    Messages: 1,016

    No caps and rotors anymore, not sure when they stopped using them, but its been a pretty long time. The 6.0 has 8 individual coils mounted right on the valve covers directly above each plug...plug wire sets are 8 identical 9" wires. I believe all the Gen III V-8 (4.8, 5.3, 6.0) use thise design.
     
  6. coach

    coach Junior Member
    from ct
    Messages: 10

    Check the fuel pressure regulator they tend to go bad on g.m.'s. Also the ignition switches are another problem.
     
  7. mayhem

    mayhem PlowSite.com Addict
    from Peru MA
    Messages: 1,016

    Where is it and how do I check it?
     
  8. coach

    coach Junior Member
    from ct
    Messages: 10

    Pressure regulator is on the driver side fuel rail, middle of motor just above the valve cover.
    It has a rubber vac line to it. Pull off the line and see if there is fuel coming out of it, if there is replace it. Also fuel may not come out right away.
     
  9. mayhem

    mayhem PlowSite.com Addict
    from Peru MA
    Messages: 1,016

    Engine running so the fuel system is pressurized and the vacuum source is active I assume?
     
  10. coach

    coach Junior Member
    from ct
    Messages: 10

    Engine off, the diaphram in the regulator goes bad so fuel gets into vac line
     
  11. mayhem

    mayhem PlowSite.com Addict
    from Peru MA
    Messages: 1,016

    Found it, pulled the line and about a teasponn of gas poured out, so it seems I'll need to replace it. Safe DIY with basic tools or should I not mess with it since its connected to a pressurized fuel line?

    Thanks for the help, hopefully this will resolve my issue.
     
  12. coach

    coach Junior Member
    from ct
    Messages: 10

    It's pretty easy, there is a snap ring that holds it in take that out, pull out the regulator mmake sure you get all pieces out, there are 2 o-rings I think? Reverse procedure and your done. take about 5 min.
     
  13. aus316

    aus316 Member
    Messages: 51

    fix

    1 snap ring 60 psi fuel pressure (watch u eyes)4 pices with 2 o-rings remove and replace in reverse good luck :gunsfiring: