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6.9 what the heck is going on!

Discussion in '6.9L IH & 7.3L IDI Diesels' started by Dodonne2, Sep 19, 2019.

  1. Dodonne2

    Dodonne2 Registered User

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    So I bought a 6.9 off of Craigslist last night drove it home for about an hour and immediately started overheating to L on the dummy gauge, Dash gauge. The truck never actually went to full red line and showed no signs of steam or smoke so I continue to drive it home. I got it home that night and as I was pulling into the neighborhood it started to lose idle and lose power under acceleration and start throwing out a lot of Blue Smoke. i parked it for 10 mins started it back up and it ran fine for 5 minutes enough to get me all the way home but pulling in to the drive it started idling horribly and cutting out under load. I floor it and it jerks and stumbles to accelerate and when I lift off it blows a lot of blue smoke. I parked it started at the next morning started fine runs great for about 20 minutes until it heats up and then starts chugging losing power and rough and won't idle. Thinking I fried the head gasket or did some internal damage through overheating it, today I went and put a new mechanical gauge on the side of the block. To my surprise as the truck supposedly overheated on the dummy gauge and the erratic idle began to ensue the new mechanical Bosch temp gauge read 190 degrees. Apparently the truck isn't overheating. The previous owner put a brand new radiator and thermostat in it, and the water pump looks a few years old. I put a brand new Motorcraft thermostat in it today as well before I actually got a temperature gauge and realized it wasn't overheating. So now it runs incredibly rough barely idles unless I give it gas and when I give it gas it is billowing massive amounts of blue and almost looks like white smoke to me. I'm really hoping it's not a head gasket does this sound like one? I'm going to start it tomorrow morning and see what happens. I'm starting a now believe it might be injectors not working properly once they get to temperature. Is this a possibility? How about maybe just a malfunctioning lift pump. It almost feels like fuel pressure loss to me. The cutting out and loss of power under load. But why would that only begin to happen 15-20 minutes after driving it when it is heated up. From what I understand the truck has been sitting for a while and was only used to gather firewood by the previous owner and then it would sit all winter. Thanks!
     
  2. ocnorb

    ocnorb Full Access Member

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    I'm sure no expert, but your fuel system seems like the place to start. Change the fuel filter, maybe open up the old one and see if there is any evidence of pluggage. If the truck sat that much it may have had some chunky fuel in it.

    These are known for having issues with the in-tank pickup screens (shower heads). Guys here that know may tell you to start at the fuel tank and work your way forward checking for leaks, pluggage, etc.
     
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  3. IDIBRONCO

    IDIBRONCO IDIBRONCO

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    To add to this, the issues will start at about 1/4 tank because the fuel pick ups aren't touching or are barely touching the fuel. Try putting 5 or 10 gallons of fuel into the tank that you're running on now if it's around 1/4. If you're going up or down hills or around corners, the fuel will slosh around inside the tank. This will cause changes in the fuel level right at the bottom of the pick up.
     
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  4. Dodonne2

    Dodonne2 Registered User

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    So after all that now it just puffs white and blue smoke bad upon startup and barely idles, misses, and coughs when I rev it up it will go but puts out major whiteblue smoke. Ive put a new lift pump, dropped the tank and made sure there was no blockage on the fuel pickup unit. Did I fry the head gasket when it possibly overheated driving it around for 2.5 hours before I put the new thermostat in CORRECTLY. The previous owner had the rubber outer protective shipping lining on the thermostat still when he installed it. So I very possibly could have fried the head gasket?
     
  5. ocnorb

    ocnorb Full Access Member

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    I think you may want to do a compression test. Maybe even get a combustion gas leak test kit and see if your pushing past the head gasket into a coolant passage or if it is cylinder to cylinder.

    The should cost little to nothing and get you a baseline idea about what the motor needs. You seem to have the same luck I do.
     
  6. dgr

    dgr Full Access Member

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    That rubber ring on the outside is meant to be there. Some people remove it to get more flow. But it's not a shipping protector. @icanfixall taught me this.
     
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  7. Grange Bond

    Grange Bond Registered User

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    Check return line is clear
     
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  8. Dodonne2

    Dodonne2 Registered User

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    Update

    I drop the tank made sure there was nothing blocking the sending unit. Pulled the lines off of the fuel tank selector valve and made sure there was no blockage, there was plenty of fuel being pushed through the selector valve toward the engine with the key turned to on. This means the sending unit is working right? I put a new lift pump in it. I bypassed the water separator by just connecting the in and out lines. I put all new return lines from each injector and from the fuel filter going to the injectors. I didnt change the return line that drops down the back of the engine back toward the tank.


    Now the truck won't run unless I go Full Throttle on a start, it will blow out major amounts of blue white smoke for about 2 to 3 seconds as it revs up and then dies. It's like there's no fuel getting to the engine or it has fuel for a few seconds. I have very little pressure at the shrader valve on the fuel filter once I decompress it after the engine dies. I will have someone crank the engine tomorrow while I decompress the shrader valve to see if there is any pressure at all. But I feel like there should be some build up pressure on that shrader valve even if the truck only runs for a few seconds. Lack of pressure at the fuel filter to me says I am not getting fuel which explains why it runs for 3 seconds then dies. If I try starting it without giving it gas it will chug a couple times then turn off.

    Any ideas?

    Thanks!
     
  9. Selahdoor

    Selahdoor How can I help you, or make you laugh, today? Supporting Member

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    Sounds like a clogged fuel filter.
     
  10. Dodonne2

    Dodonne2 Registered User

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    I know fuel filter was the first thing I changed though. Maybe another one? Did I pick up some real nasty fuel crud on the drive home? I filled it up once and never ran it below 1/4 tank on the gauge.
     
  11. mexicanjoe

    mexicanjoe Full Access Member

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    plugged muffler perhaps?
     
  12. SumKindaRanch

    SumKindaRanch Full Access Member

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    Remove the muffler, if that doesn't help get it compression checked, could be cavitation. Mine was acting similar before it blew the block. Also pull valve covers, it could have a bad rocker or bent valve
     
  13. RetiringColt

    RetiringColt Supporting Member Supporting Member

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    My understanding is that you installed a aftermarket temp gauge and the temperature is at 190°? As long as the coolant was full and pressureized and flowing. The cooling system should be sound. Does the engine ever smooth out or clear up? If not, a compression test would be a good place to start. Maybe a possible valve train problem. Other than that. It sounds like you are on the right track with the fuel system. Mine had two loose injection pump bolts and I believe it gradually slipped timing after I bought it. Bad white smoke on cold start.
     
  14. Dodonne2

    Dodonne2 Registered User

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    I am not sure if the cooling system was operating correctly because of the thermostat install by the previous owners, the truck never started blowing off steam, I just had a temp reading on the dash gauge of A-L. I installed a new thermostat and drained the coolant. Then I installed a new mechanic gauge which told me the truck wasnt overheating, but that was AFTER i changed the thermostat and the coolant system. So I am not sure if it overheated or not.

    UPDATE:

    It will start briefly chug a few times and then shut off. If I give it wide open throttle it was start and rev up to about 2500 rpm and then just die after 4 seconds or so of total run time. I have tested the schrader valve and I have plenty of fuel spewing out at the fuel filter head when the truck is turning over which means I have fuel pressure to the top of the engine. Could it be a clog in the return lines somewhere that I missed. I have already changed all return lines and caps. I have flushed all fuel lines from tank to fuel filter, changed return lines and flushed return lines all except the line heading down the back of the engine towards the tank.

    Is this sounding like a head gasket to anyone?? Previous owner had a new thermostat in it and a new radiator which leads me to believe he overheated it at some point....

    did the IP slip and lose timing? Is the IP toast?

    I will do compression test once it stops snowing here in CO.

    Thanks for any advice
     
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  15. Thewespaul

    Thewespaul Supporting Vendor Supporting Member

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    Buy a used ip and swap it on.
     
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