2016 carrier 7500

Discussion in 'Refrigerated Trucking Forum' started by 062, Feb 26, 2020.

  1. 062

    062 Road Train Member

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    I have a 7500 that’s sucking air. I believe it’s between filter head and pump. Mainly because it stumbles at startup. @reeferwrencher are there any common places for these to suck air and do the primer pumps give trouble on this unit?
     
  2. reeferwrencher

    reeferwrencher Light Load Member

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    Pump shouldn't be a problem remove the inlet line from the pump it's a 3/4 inch bolt there is a fuel filter screen that threads into it unthread and make sure it's not clogged with sludge if so blow it out with solvent or air reassemble with new copper washers thermo king part number 55-2208 pressurize fuel tank through tank vent prime and check for any leaks
     
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  3. 062

    062 Road Train Member

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    I’ve already cleaned the screen. I haven’t pressured the tank yet, but no visible leaks. I’m going to start with the spring clamps and replace with worm clamps. I have a feeling one of them is letting air in. I just wanted to know if this was common with these units.
     
  4. reeferwrencher

    reeferwrencher Light Load Member

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    It happens on all models tighten all the brass fuel fitting you could pull the pick up line out of the tank as well and make sure its cut on an angle and isn't forced against bottom of tank seen that many times but pressurize tank and look for any small leaks for sure
     
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  5. MRMTRANS

    MRMTRANS Bobtail Member

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    Buy a spare fuel tank cap. Drill a hole in the center-7/16" bit if I remember-and buy a 1/4" NPT tap from a hardware store, and tap away. The size of the drill bit to use will be on the package of the pipe thread tap. Screw in an air line quick connect with and pressure away with a cheap air pressure regulator from Harbor Freight set at 40 lbs. You might see fuel at leaking at the ends of the supply and return lines. If not visible, I would just tighten down on all of the ferrels around all of the line's ends. If it still loses a little prime sometimes-particularly in cold temps-cut the ends of the fuel lines back some and put new ferrels on at the same time. The cap and the pressure regulator (for pressurizing while out on the road with air from your truck that is governed at approx 120 lbs) is good to keep in the truck. Then you don't have to hassle with the little primer pump.
     
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  6. 062

    062 Road Train Member

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    This one has rubber lines with spring clamps from the filter head to pump. It’s not giving any real trouble now, but I know it’s not going to get better. As it is now it may go days and not stumble. The day I started this thread it was fine until I was ready to go to bed, then it would stumble for 1-3 seconds.
     
  7. MRMTRANS

    MRMTRANS Bobtail Member

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    Keep in mind, a leak anywhere in the fuel delivery system (including return line) can cause it to lose prime. I learned this the hard way as my trucks engine kept increasingly losing prime, and I eventually figured out there was a small crack in the return line coming from the head, going to the fuel tanks. It wasn't until I put pressure to the fuel system with the truck engine off that I saw fuel spraying from that line. I would simply just change lines, starting with the one between the filter housing and the pump, one at a time and see if the problem goes away.
     
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  8. Blackhorse77

    Blackhorse77 Light Load Member

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    @reeferwrencher
    Why Thermo King Whisper Units are priced lower? What kind of problems these get along the way?
     
  9. reeferwrencher

    reeferwrencher Light Load Member

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    Because they're old units and not nearly as good as the sb210/230 or sb310/330
     
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