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5.7 Vortec. No Power

Discussion in 'Chevy Trucks' started by Racer593, Sep 27, 2009.

  1. Racer593

    Racer593 Member
    Messages: 71

    OK everyone here we go. 99 Suburban K1500 4x4 5700 Vortec.
    This started while plowing at the end of the season last spring.
    When you start it, it starts, runs and idles well. after a short bit of driving(couple miles) it acts like it is starving for fuel if you give it more than about 1/2 throttle. I'm talking horrible here. Falls on it's face and starts to miss and loses speed. IF you pedal it it will gain speed but just at a slower pace. Basically you can't pass or gain speed in a hurry.
    Here's what has been replaced so far.
    Fuel pump and filter
    Air filter
    all 4 O2 sensors
    Coolant temp sensor
    Crank pos sensor(Showed bad)
    ECM(worked for someone on another site)
    Cap, rotor, plugs and wires(AC Delco and Packard)
    Exhaust gasket BEHIND convertors(Blew Out)
    Not an electronic gas pedal.
    ((((((((((((((((((No SES Light at all))))))))))))))))))
    If you get mad and mat it and hold it on the floor, it smells very hot in the exhaust, I mean like you're welding it hot.
    I've run it with no O2 sensors in it, its not plugged convertors. If you shut it off while it's acting up and wait about 10-15 seconds and restart it, it goes away for a bit, like something resets. It has been scanned with a Tech II, top of the line Snap-On scanner, been to three different shops, INCLUDING GM Goodwrench, and while all have had suggestions(read:throw lots of money at it), no one has been able to fix it yet.
    Now I'm laid off, and I don't have the money for the truckside mount on my new truck, so I really need to get this thing figured out.
    I've read hundreds of pages on here over the last month or so(laid off so I've got the time)and haven't found this type of problem for anyone else.
    I know there are many VERY knowledgeable members on here. I just hope someone has an idea. Thanks in advance.
    Sorry for the long post.

    Chris :confused::realmad:

    P.S. It's also my wife's 'Burb now so I REALLY need to get it fixed now!! LOL
  2. cubicinches

    cubicinches PlowSite.com Addict
    Messages: 1,415

    Have any of the shops checked the mass air flow sensor? Have it scanned for erratic gm/sec MAF readings, or try a know good one. Typically, this would set a code, and you'd have a check engine light... but anything is possible.
  3. Racer593

    Racer593 Member
    Messages: 71

    Yep. Replaced it also. Sorry, forgot that one. I've done so much over the past 9 months its hard to remember everything.
    Thank you though.

  4. Sydenstricker Landscaping

    Sydenstricker Landscaping PlowSite Veteran
    Messages: 3,882

    did you do the fuel pressure regulator as well??
  5. google 1996-2000 vortec csfi recalls\service bulletins they are a known piece of crap(by gm) that will give you symptoms of all kinds similar to what you are describing. There is a updated gm part that gets rid of the poppet style injectors and replaces them with real ones. You can also get them aftermarket now from napa etc I put one in my 96 k2500 similar symptoms to what you are describing very frustrating. If you aren't seeing any codes and looking at what else you have done I would investigate this as well as weak fuel pressure (I know you did the pump but you did not say if they actually put a gauge on it)
  6. Racer593

    Racer593 Member
    Messages: 71

    Thanks Sydenstricker & Luke P. Pump pressure was over 62psi while driving, under load. Seems like something else about injectors has sort of come up before in my travels. I'll have to check into the injectors and possibly the regulator. Any ideas are welcome!! LOL

  7. Racer593

    Racer593 Member
    Messages: 71

    One thing I haven't tried is injector Cleaner. Reading around found a few that have done it and it cleared it up. A few bottles of injector cleaner is ALOT cheaper than the 500 dollar conversion right now. Thanks Luke for pointing me in that direction.

  8. If it is indeed your injectors and the cleaner works I would consider it borrowed time when GM first started cleaning them they found it pretty ineffective and moved to component replacment (I forget the exact timeline but at first they switched the bad poppets if they could then started using the updated part) and eventually went back to cleaning or poppet replacement because doing it right was costing to much. Check gm parts direct online I couldn't get it because I am 1 in canada and 2 nedded it yesterday my local stealership was $900 or so and napa around $600 (canadian). GM parts direct was like 300 for the gm part or something like that I looked on there the other day to find one for a friend and couldn't find it (forgot the #) but I am sure they will have it. May be worth looking into for down the road if the cleaning works.
  9. brad96z28

    brad96z28 PlowSite.com Addict
    Messages: 1,525

    Sounds like u may have a fuel volume issue U could have 62 psi and crap for volume. Was a volume test performed?
    Last edited: Sep 28, 2009
  10. Racer593

    Racer593 Member
    Messages: 71

    Nout sure but probably just pressure. You know small town, small shops...AND a tight a$$ that just can't bear to take it to the stealership.(one of my guys IS a Goodwrench service manager with a Tech II at home though!!!!)

  11. scottL

    scottL PlowSite.com Addict
    Messages: 1,613

    MAP Sensor is all you really have left.

    I had issues with the MAP sensor. It did stumble but, not too bad - mostly at cruising speed and throttle.

    Your description sounds exactly like the injectors. The older design would get to a point and simply fail - no codes on mine. Replaced them with the new version and bingo!
  12. ahoron

    ahoron Senior Member
    from here
    Messages: 422

    Fuel pump wasn't from autozone or advanced was it? Had same problem replaced injectors and everything else. Then replaced the pump with ac delco problem solved.
  13. Racer593

    Racer593 Member
    Messages: 71

    Nope AC Delco... I heard that before I changed it.


    NICHOLS LANDSCA PlowSite Veteran
    Messages: 4,362

    Vac leak/intake gaskets?
  15. brad96z28

    brad96z28 PlowSite.com Addict
    Messages: 1,525

    Even with a tech 2 It is only as good as the guy using it.
  16. Racer593

    Racer593 Member
    Messages: 71

    He was actually born into a family owned Chevrolet dealership that was a staple here in town for years.Small town, dealer got bought up by bigger dealer from the city then they closed it about 2 yrs later. But he's had a wrench in his hand since day one!!! I do agree, though,you do have to have some knowledge to use it......

  17. scottL

    scottL PlowSite.com Addict
    Messages: 1,613

    I was just thinking ....... 62psi seems low. I thought the fuel pressure test was to put the gauge on. Turn the key to build fuel line pressure. I believe 70-90 psi. Then turn the key and see where the pressure is at 1 minute. If it drops below 68 then your pump is bad. I remember going through 3 brand new GM pumps before finding a good one. It can happen.
  18. 2COR517

    2COR517 PlowSite Fanatic
    Messages: 7,115

    It would seem to me if the pump can maintain 62 PSI while the engine is running, volume would have to be sufficient.
  19. cubicinches

    cubicinches PlowSite.com Addict
    Messages: 1,415

    60 - 65 psi is the correct fuel pressure. If it maintains 62 psi while running, the pump is fine.
  20. Banger

    Banger Member
    Messages: 70

    I have a few chevys in my fleet and I had simular issues as you descibed or DEAD ON!!!!

    It turned out to be the TPS (throttle Position Sensor) both times.

    Not sure if yours has a ICM (Ignition Control Modual) but simular issues may happen as well before full failure of that unit.

    Also I had the exact same issue before on a older chevy I had years back It was a 92 K1500 with a 350 and throttle body injection.I had a Spark leak .. I had brand new plugs on the truck so I never thought of rechecking them. Just happened to open my hood at night and noticed the spark jumping ever so lightly on or near the exhaust manifold.The wires were all routed away from the exhaust but I guess when it got windy under the hood while driving or plowing ect... the wire in question touched the manifold and melted a section I couldnt even see.
    Probley not your issue but worth checking!

    Not sure if you threw a code or not. Dont recall seeing you did but from what I know... With no codes in the computer this is saying it is a mechanical problem and not an electrical problem.

    I'm banking on the TPS though. It will forsure cause everything you said without doubt!! However, you should have a code though. Might want to reset the PCM and see if it trips a code after some time.
    Last edited: Sep 30, 2009