Here we go again...ISX won't start

Discussion in 'Trucks [ Eighteen Wheelers ]' started by bigrigr, Oct 28, 2013.

  1. bigrigr

    bigrigr Bobtail Member

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    So now I am more cautious this time aboout flying off the handle and doing something crazy(after my last post), but i have Another problem with this kenworth i just purchased. I took the truck to my regular mechanic to have a full service done, and after they replaced all the fuel filters, it woudln't start over their pit.(the primer pump was whirring away everytime i turned the key to the on position) Long story short, they diagnosed it as a bad high pressure pump. I left it there over night, and in the morning they put a pump on and they claimed it started right up. I took the truck home and all seemed well until yesterday. The truck sat overnight and mosat of the day yesterday, and then around 3pm i went to start it and it did the same thing as it did over their lube pit. I pulled the fuel filters and found the fuel levels inside to be low. So i topped them off with fresh diesel and reinstalled them with no luck. I replaced them with two new filters(making sure to top them off to the brim with fresh diesel). and i still cannot get it to start. The closest i can get it to running is the 2-3 second burst when it starts, then sucks the filters low on fuel again. I have nearly 1/2 tank of fuel on the right side and over 1/4 on the left. I messed with it for several hours last night to no avail. Anybody have some wisdom for me on this? I'm no dummy when it comes to mechanical things, but this ISX is all new to me. Thanx again in advance
    p.s. i should probably note that both times this happened, the a.p.u(rigblaster) was run with the main motor off, first time it ran for about 30-45 secs to fill the new oil filter up. the second time it ran for about 30 mins while i worked inside. fwiw
     
  2. LBZ

    LBZ Road Train Member

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  3. bigrigr

    bigrigr Bobtail Member

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    I didnt want to update either, i was forced to do it by big brother and the great state of california. I live to close to the west coast to simply write it off and never go there. All of this just makes me hate this truck already. I gave up a great running accert in a pete for this?????
     
  4. fortycalglock

    fortycalglock Road Train Member

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    You're sucking air somewhere. You just need to find out where.

    ETA, simply adding fuel to your filters usually won't let an air locked engine start. Pressurizing your tanks with air is the best way, or if an emergency a small amount of starting fluid. Since it is not an emergency, I'd pressurize the tanks and start cranking.
     
    Intothesunset Thanks this.
  5. Heavyd

    Heavyd Road Train Member

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    Yep, sucking air. You would need to install a test draw line for the inlet of the electric primer pump right into one of the fuel tanks and see if picks up fuel. You could have a cracked pick up tube at about 1/2 to 1/4 full mark, or a pin hole in one of the lines.
     
  6. bigrigr

    bigrigr Bobtail Member

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    Thanks guys, i ended up using the starting fluid. It didn't take much to get it running on it's own(thank heaven). And once i got it running it ran like a dream and i shut it off and restarted it several times yesterday with no problems. My mechanic mentioned that he changed some "check valves" as a precaution while they did the high pressure pump. But found out that they were old take offs he had lying around. What do these check valves do? I wonder why he had them "lying" around.....It seems that the primer pump maybe is shot? It comes on and sounds good, but it sure isn't priming anything. I will try the clear hose into the tank, and see what happens then. If i had a leaking pickup tube, wouldn't it run bad, stall, etc as well?
     
  7. sinnano7

    sinnano7 Bobtail Member

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    check valves hold fuel so its always there..ive replaced a lot of primer pumps but only when they have quit running,never heard of one not working that is still operating, like they said ,I think you are sucking air through a stand pipe or dried up cracked fuel lines..ISX's sre good engines
     
    Intothesunset Thanks this.
  8. special-k

    special-k Road Train Member

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    The neighbor has an old cascadia with an isx
    in it. Same story as yours starts ok some times other times just spins over. They put new fuel lines on it, replaced the electric fuel pump . I was better but not cured. They ended up putting a new gear reduction starter on it (it had an old style delco on it) and 4 good batteries and its been fine all summer. We'll see in the winter.
     
  9. snowwy

    snowwy Road Train Member

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    my air leak was the pump. as long as the tanks were full it was fine. but below half. and starter fluid was required. the idle would also be erratic.

    but you could actually see bubbles from the housing.

    i was told there are 2 pumps. the buzzing is the high pressure used to start the engine. supposedly it shuts off when the engine starts and runs off the low.

    i also had a electrical issue that was 2 months before it got fixed. pump went out next month. but the electrical issue was a hot wire from the starter to the ecm. runs along the frame. where a section of insulation had worn through causing the exposed portion of wire to touch the frame and short the ecm into shutting down the engine.

    those were the only 2 run problems i had with that truck. other then that, it was a darn good truck. it was an 05 w9 with isx.
     
  10. bigrigr

    bigrigr Bobtail Member

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    Turns out it was the primer pump, apparantly the motor still worked, but the pump part had stopped working. Ended up pulling the line off the primer pump inlet and running a hose into a bucket with fuel. Turned the key on and started the pump. Nothing in the bucket moved, it wouldnt even suck enough to wet the inside of the hose. Put a new pump on and it has worked like a charm ever since. Thankx for all the replys. On to the next disaster.....
     
    Heavyd Thanks this.
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