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3406B accelleration problems

Discussion in 'Trucks [ Eighteen Wheelers ]' started by Wildcat74, Mar 27, 2011.

  1. Mar 27, 2011 #1
    Wildcat74

    Wildcat74 Medium Load Member

    354
    128
    Jul 15, 2008
    Omaha, NE
    0
    My old 359 Pete that I pull my end dump with has some major problems accellerating when loaded. There is no excessive smoke but the motor is only making about 17lbs boost max. It's a remanned Cat with an unknown amount of miles. Throttle response when in neutral is nice and crisp, it's just when driving it can take literally a mile and a half or two miles to get to 55-60mph on flat ground. The truck is a real turd when pulling hills as well. About 3000 miles ago I had the valve train and jakes run and a new set of rods and mains rolled in. The truck had this issue before all of that. Is it maybe just not advancing enough? I'm no mechanic so I don't really even know where to start.
     
    Wildcat74, Mar 27, 2011
    Wildcat74, Mar 27, 2011
    #1
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  3. Mar 27, 2011 #2
    Wildcat74

    Wildcat74 Medium Load Member

    354
    128
    Jul 15, 2008
    Omaha, NE
    0
    Just to add a little more info: Truck has 13sp. Supposed to be a 425 Cat but it feels more like 300. Does about 62 mph at about 1750 rpm so I'm guessing it's got 3.8-3.9 rears. Drives nice and smooth, stays under 175ish degrees unless it's a hot day. Pyrometer never gets much over 850 degrees even at 80k. never goes under 40lbs oil psi and oil temp stays under 180.
     
    Wildcat74, Mar 27, 2011
    Wildcat74, Mar 27, 2011
    #2
  4. Mar 28, 2011 #3
    bean farms

    bean farms Light Load Member

    118
    3
    Feb 25, 2011
    red boiling springs tn
    0
    does it black smoke any at all it could be your air fuel diaphram in your injection pump some times the go bad and it wont let it build much boost because its all goin in your crank case and it cant fuel as hard with out this and it may just need turned up
     
    bean farms, Mar 28, 2011
    bean farms, Mar 28, 2011
    #3
  5. Mar 28, 2011 #4
    Wildcat74

    Wildcat74 Medium Load Member

    354
    128
    Jul 15, 2008
    Omaha, NE
    0
    The truck doesn't hardly smoke at all, either when cold or hot. I've always wondered if it was just turned way down or if there was some sort of bigger problem going on though.
     
    Wildcat74, Mar 28, 2011
    Wildcat74, Mar 28, 2011
    #4
  7. Mar 28, 2011 #5
    bean farms

    bean farms Light Load Member

    118
    3
    Feb 25, 2011
    red boiling springs tn
    0
    i would turn it up and see if that helps and if it dont change the afc diapram
     
    bean farms, Mar 28, 2011
    bean farms, Mar 28, 2011
    #5
  8. Mar 28, 2011 #6
    SL3406

    SL3406 Medium Load Member

    550
    1,491
    Jan 10, 2011
    Oklahoma
    0
    The first thing I would do is check the fuel pressure when its under a load. The fuel lines could be going bad if they haven't already been replaced.
     
    SL3406, Mar 28, 2011
    SL3406, Mar 28, 2011
    #6
  9. Mar 28, 2011 #7
    Diesel Maniac

    Diesel Maniac Bobtail Member

    7
    1
    Mar 26, 2011
    NC
    0
    I have seen worn out timming advance cause the same problem. It is located in the front section of the injection pump.I would sugest to have a qualified tech to inspect it for wear. When the mechanism wears it will stick and not advance you timming durring a hard pull.
     
    Diesel Maniac, Mar 28, 2011
    Diesel Maniac, Mar 28, 2011
    #7
  10. Mar 28, 2011 #8
    Les2

    Les2 Road Train Member

    5,150
    2,288
    Jul 25, 2008
    kicked back in my lazyboy...
    0
    Good idea! IIRC the lowest the pressure should be under a pull is 25lbs.

    If this was the case the motor would rattle more than usual with the timing not advancing at lower RPM going up thru the gears.

    It's an easy fix if you have some idea of what you are doing. There is really just some seals, o-rings in there. When they go bad it allow oil to push past them not advancing the timing.

    If this motor has been like this since you've owned it, there is a good chance its just cut back. A good way to check before messing with fuel settings, is take the cover off the AFRC valve and see how far that screw is turned. If its out and you can see a good bit of it, that might be your problem. Just loosen the jam nut and turn the screw in a few turns. Since you said it doesn't smoke, I'm gonna bet thats your problem.

    I think stock it should pull 18-21lbs of boost.

    Do you know the serial number?
     
    Les2, Mar 28, 2011
    Les2, Mar 28, 2011
    #8
  11. Mar 28, 2011 #9
    SL3406

    SL3406 Medium Load Member

    550
    1,491
    Jan 10, 2011
    Oklahoma
    0
    Retarded timing would create smoke and high e.g.t. temps. He says he has no smoke, low exhaust temp., and low boost which sounds like not enough fuel to me.

    I agree with Les if its always been this way the pump is probably set at stock settings. I would still check the fuel pressure under load to be sure it is being supplied with enough fuel.
     
    Last edited: Mar 28, 2011
    SL3406, Mar 28, 2011
    SL3406, Mar 28, 2011
    #9
  12. Mar 29, 2011 #10
    bean farms

    bean farms Light Load Member

    118
    3
    Feb 25, 2011
    red boiling springs tn
    0
    and if you cant get what your looking for win you turn the afc screw in you might want to look into the fuel rate and torque rise screws you can turn them out about four rounds and it will make a big diff. i most of the time go two but yours ant smoking nore making any boost i would go four and you turn those screws out not in like the afc
     
    bean farms, Mar 29, 2011
    bean farms, Mar 29, 2011
    #10
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