1981 International Toter truck NTC 300 Big Cam, cranks but dies under a load.

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by cody r, Jan 21, 2021.

  1. cody r

    cody r Bobtail Member

    1
    0
    Jan 21, 2021
    0
    I have a 1981 International Toter truck with a NTC 300 big cam and 10 speed Eaton fuller transmission, clutch just got changed, the truck was pulling mobile homes without issues. Until 5 days ago when I was pulling one, 20 minutes before getting to my destination the truck started to loose power on a uphill. It went from 60 mph to 45 mph and I was able to go back to 60 mph on a flat road then 10 minutes later I went to another uphill. Then this time went from 45 mph to 20 mph ,the last uphill I was going really slow 5 mph ,the engine did not shudder or made any bad noise. It was just late to respond and I was pressing the gas pedal all the way down but it kept being weak. The truck cranks fine and the engine does not shake or make a bad noise. It moves and shifts fine just when I tried to pull a mobile home off the lot it dies if I press gas all the way down.
     
  2. Truckers Report Jobs

    Trucking Jobs in 30 seconds

    Every month 400 people find a job with the help of TruckersReport.

  3. BoxCarKidd

    BoxCarKidd Road Train Member

    3,134
    4,278
    Aug 26, 2014
    0
    Does the throttle lever on the pump brake over? It is a spring loaded deal. Maybe it slipped on the shaft.
    Changed the fuel filter?
     
    black_dog106 and Dino soar Thank this.
  4. SmallPackage

    SmallPackage Road Train Member

    2,106
    5,666
    Dec 20, 2019
    Marion Texas
    0
    How is the fuel filter? Has it been changed lately? If it is less than 3/4 full when you remove it then you are having a suction problem.

    Is it holding rpm or just falling down to idle with peddle full throttle?

    Sounds in your discription that it runs and feels like normal power when bobtail but has no power when hooked to trailer?

    Start at fuel filter and air filter.
    Check fuel pump for any external fuel leaks from it. Throttle shaft and afc diaphram on the backside of pump that the manifold aftercooler tube goes to. They are the biggest leakers these days. The new fuels eat the o-rings and the rubber diaphragm. Both of those will make you lose power. The afc is most noticeable when you need boost. If its bad it will not let the turbo boost.
     
    black_dog106 and Dino soar Thank this.
  5. Dino soar

    Dino soar Road Train Member

    3,052
    7,527
    Dec 8, 2017
    0
    As boxcar said check the linkage at the pump.

    It sounds like a fuel problem so I would suggest changing filters. I would cut the fuel filter open and visually look inside of it dump it out into something clear and see if you have rust or algae or anything else in the filter. If so you will have to clean your tanks. Examine the pump itself to see if it's wet with fuel anywhere around the pump. I would screw in the fuel solenoid all the way so that you know that it's completely open.

    On older trucks it is possible that the actual fuel liines can collapse internally and can supply you with enough fuel to start and run but under load you can't get sufficient fuel.

    If the truck will die under acceleration sitting still, I recommend that you disconnect your fuel line and use a can that's up higher than the pump and run your own line to it and see if that helps.

    I would try that 1st but also inside the pump there is a plunger that controls the boost. So if that plunger went bad you will have no boost to pull under acceleration and the truck will feel like it has no power.
     
    black_dog106 and Roger McG Thank this.
  6. BoxCarKidd

    BoxCarKidd Road Train Member

    3,134
    4,278
    Aug 26, 2014
    0
    A lot of good info right there! When low sulpher fuel came out ( around 1992? ) we were having PT pumps rebuilt left and right. With this fuel today I am seeing that again just not many PTs left around.
    Diagnose first instead of swapping parts. Those guys know a lot more if you answer their questions first.
     
  7. Happily Retired

    Happily Retired Road Train Member

    8,402
    15,964
    Apr 16, 2014
    high plains colorado
    0
    SHINY 290!!! They were great motors. BC Cummins always have water in the fuel, because, Cummins returns a lot of warm fuel back to the draw tank, and in the winter especially, the fuel cools off overnight and condensation forms, leaving a puddle in the bottom that gets sucked into the filter. If you take a flashlight and look in the tank, I'm sure there's water in there. I used to carry several fuel filters just for that reason.
     
    bzinger Thanks this.
  8. A5¢

    A5¢ Medium Load Member

    367
    495
    Oct 30, 2017
    0
    I used to drive a GMC General, with a 350 Cummins that did something similar to your issue. It turned out to be a cracked fuel filter base. It would not do it all the time and that made it tough to find.
     
    bzinger Thanks this.
  9. SmallPackage

    SmallPackage Road Train Member

    2,106
    5,666
    Dec 20, 2019
    Marion Texas
    0
    I have lots of new throttle shaft o-rings and afc diaphrams as spares. Just had to do a throttle shaft leak 2 weeks ago. It was dripping on the ground. Nothing else wrong and still ran ok. Just leaving drips on the ground. Lol
     
    black_dog106 Thanks this.
  • Truckers Report Jobs

    Trucking Jobs in 30 seconds

    Every month 400 people find a job with the help of TruckersReport.

  • Draft saved Draft deleted