Exhaust Smoke going Downhill

Discussion in '6.9L IH & 7.3L IDI Diesels' started by Stock90IDI, Dec 27, 2017.

  1. Stock90IDI

    Stock90IDI Supporting Member Supporting Member

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    Update:

    Returned to Cali a couple of weeks ago and truck didn't smoke as bad. Wife was following in her car and said she could smell strong diesel fuel smell most of the trip, especially on the down hills. Otherwise truck ran good as usual, 17mpg empty between Bend and Klamath Falls.

    Last weekend I did the ATF in fuel filter trick but was still waiting for Ferret tool to arrive to check timing. First tried repeating the 2000+ rpm with no load to see if it smoked like it did over Christmas. No smoke but strong smell of diesel in exhaust. I then did the ATF trick and let set overnight. Next day drove it to flush out of the system. Again, didn't smoke afterwards but still had a strong diesel fuel smell in exhaust.

    Today I checked the timing and looks like advance is only 4 deg not 8.5 per the manual. IP factory timing marks are aligned perfectly. Guess I'll have to make a bent wrench and adjust the IP timing so it is proper at 8.5 deg then test for smoke again.

    I'll post an update again after.

    Factory IP Marks.JPG

    0deg advance.JPG

    Timing Marks at 0deg Advance.jpg

    4deg Advance.JPG

    Timing Marks at 4deg Advance.jpg
     
  2. Shadetreemechanic

    Shadetreemechanic Full Access Member

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    Like others have said, its probably your timing, probably caused by a bad pump. Try the cleaning, if it still smokes, take a screwdriver and try pushing the advance piston on the drivers side of the injection pump while at idle. That should make it run like crap. If you notice no change, then its definitely the pump. I had one go bad and do exactly the same thing you describe.
    27 years aint a bad life for a pump.
     
  3. Stock90IDI

    Stock90IDI Supporting Member Supporting Member

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    Already tried the cleaning. I’ll try pushing the advance piston tomorrow and see how that goes.
     
  4. Stock90IDI

    Stock90IDI Supporting Member Supporting Member

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    Pushing the advance piston at idle basically made little to no difference....it certainly didn't make it run like crap. Looks like a new IP in is my future. Since the injectors are original as well, does it make any sense to change them along with the pump or wait until they give me a problem?
     
  5. Thewespaul

    Thewespaul Supporting Member Supporting Member

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    Always change both at the same time.
     
  6. Clb

    Clb Another old truck Supporting Member

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    Just data mining for fuel sender issues...
    I have a 93 with just under 50k, gunna tag this for future reference.
    Btw I'm in napa
     

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