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  1. #1

    Default Non-existant low end power

    Hey guys, I got a new problem that started yesterday. I got a 90' burb with an all stock 350 in it. Since yesterday, it has absolutely no power up until about 2,800 RPM. It feels like a little 4-banger is trying to power a 6,500 beast. Literally, I have to floor it to even get moving. Once it hit's about 2,800, it has the normal power. It idles a little higher than normal (about 900 versus the typical 550), but it's still smooth. When I get on it, there's no bogging or hesitation or anything, just a complete lack of power.

    I put a new fuel filter in it today, which didn't help. I also got some fuel additive injector cleaner which I'm going to put in next time I fill up.

    This is confusing the hell outta me . Any got any ideas?? I don't really want to drive it until I know what's going on.
    Current truck: 1996 Ford 250, 7.3 Powerstroke diesel. Dana 60 SAS, stage 1 160cc injectors, T500 High Pressure Oil Pump, TS 6-position chip, full 4" exhaust, intake, 285 Falken Rocky Mountain AT's, boost/EGT/trans temp pillar gauges, etc...



  2. #2

    Default

    When was the last time that you replaced the ignition parts, cap, rotor, wires and plugs? Is there any smoke coming out from the exhaust? Did you do anything under the hood around the time it started that may have caused a small vacuum leak?
    Scott

    ΜΟΛΩΝ ΛΑΒΕ

    '94 Chevy Suburban K1500
    3" exhaust w/ aero turbine non-baffled muffler
    CFM Technologies TB spacer
    CB w/ 44" whip antenna


  3. #3

    Default

    I actually replaced the cap, rotor, plugs, and wires about 2 and a half months ago. Haven't had any problems up until now. And I haven't done anything motor-wise that I recall that could cause something like a vacuum leak to happen.

  4. #4

    Default

    Have you checked for any diagnostic codes?
    The description sounds a lot like a blocked up catalytic convertor.

  5. #5

    Default

    Quote Originally Posted by tbplus10 View Post
    Have you checked for any diagnostic codes?
    The description sounds a lot like a blocked up catalytic convertor.
    X2. A plugged up cat will feel just like that as well as a frozen fan clutch. Check the fan first. If you suspect a clogged cat you can check it by installing a pressure gauge on the upstream O2 Sensor port. A good flowing cat will have less that 2lbs pressure. If you have over 4 lbs pressure then you have a restriction.
    If you don't have an adaptor for the O2 sensor hole to your pressure gauge drill a hole and tap it for an eighth inch pipe. Install an eighth inch nipple and attach your pressure gauge. When you are finished just plug the hole with an eighth inch pipe plug.

    Jim
    Jim

    2004 SILVERADO 2500HD LS
    Pro Comp Leveling Kit
    285-75-16 Cooper ST All Terrains
    Pro Comp Programmer
    Bilstein Shocks
    Linux Bed Liner
    Tinted Windows



    Other rides:

    1967 Landcruiser <350 Chevy>
    1970 Camaro
    1990 Geo Metro Convertible
    2007 FJ Cruiser

  6. #6

    Default

    How would I go about checking for diagnostic codes of something this old? There's no check engine light going on or anything, but that's about all a truck this old has for engine protection lol.

    And would a clogged cat (if that is the problem) just start happening all of the sudden like that? Like it got as bad as it is within the course of like 10 minutes.

    If anyone has any other ideas, throw 'em out there!!

  7. #7

    Default

    Anybody else have any other ideas? I really would like to get this fixed before I have to start driving to school on a daily basis again on monday, because I don't know what's going on and what kind of damage it could be causing.

    And how would I check for a frozen fan clutch? Just try to spin it while the engines not running?

  8. #8
    Legend

    Join Date
    Jun 2006
    Location
    River Ridge Louisiana-4 miles W of New Orleans-didn't flood-water stopped 800 yards away.
    Posts
    1,613

    Default

    Long shot, but have you replaced the fuel filter recently? It is something that can suddenly go bad.
    I doubt that this is it, but it is cheap and easy to fix, and something that needs to be done anyway, so it is worth a shot. Frankly, I would expect it to be worse at higher power levels with a filter part plugged, but worth a shot.

    A tank of bad gas also come to mind-long shot once again.

    Fuel pump- I would expect it to be better at low power than high, but??

    It acts like it isn't getting enough fuel at low, but plenty enough at higher rpms- hence the fuel delivery ideas. I don't know why ignition parts would act that way??, so I would hunt down fuel problems

    Does that throttle body "carb" FI systemhave some sort of float and float bowl like a carb? could it be getting "stuck?? the float or the needle??

    I would start with the fuel filter-cheap and easy to replace-worth a shot

    Luck,
    Charlie
    1998 suburban-
    1/2 ton

    199500 miles
    River
    Ridge,LA

  9. #9

    Default

    I already tried a new fuel filter, didn't work. But at least I know I have a good fuel filter now lol. And my tank is almost empty after putting like 15 gallons in it, so I really don't think that's the problem.

    And I have no idea how the TBI works, so I wouldn't know if there was a problem in that or not.

    And to give you an idea of how bad this is, you all know those curved curbs, about 8 inches high right? I couldn't even spin my rear tires (in 2wd) in reverse on dirt trying to get my front tires over a bump about that size. I had to use 4-lo to get the torque to get have enough power to be able to pull my front tires over a bump the size of a freakin' curb in reverse.

  10. #10

    Default

    Did you ever check to see if there were any codes? If you didn't, find the ALDL port, it's by your right knee when you're in the driver's seat. It looks like a rectangle with two rows of smaller squares inside, almost like a serial port on a computer (kind of). Jump the two upper right ports to each other with the key off. Then turn the key on, DO NOT START THE MOTOR! The SEL will start to flash out codes. Code 12 will flash a few times and then it will start flashing other code numbers if there's anything in there.

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