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another 7.3 problem

Discussion in 'Ford Trucks' started by Darkness, Jan 12, 2010.

  1. Darkness

    Darkness Junior Member
    Messages: 6

    I bought a 1999 F350 less than a week ago with 172,000 miles on it, the other day i was driving and coming to a stop it started to shake violently. The motor sounded like it was running weak, a steady spudder. Then i came to a stop sign and it stalled out on me. I started it back up and it ran enough to get me home. It also died twice will idleing im my driveway that day.
    I did some reading on here. I changed the fuel filter and had Ford do the CPS today, but its still not running right all the time. Some times it runs fine will idle at 700 or 900. Other times it will shake violently at either RPM. When I picked it up from the stealership the guy said its "still running like poop". When I started it, it had NO power, it would not even spin the tires on snow or rev above 1200RPM, I shut it off and restarted it and it ran better, not right but like it is now. The only thing I can think of is that mabe it might be the high pressure oil pump like one guy said in another common thread. If anyone can point me in a direction to get started with this problem i would greatly appriciate it.
  2. 7.3 Plower

    7.3 Plower Senior Member
    Messages: 221

    To me it sounds like it could be the under valve cover harness (uvch) coming loose. Ford sells some shims to keep it from coming loose or you can grind down quarters to use as shims to keep it from coming loose.

    Also did you notice any smoke?
  3. Darkness

    Darkness Junior Member
    Messages: 6

    Only white smoke during start up. After its warm, none.
  4. WMHLC

    WMHLC Senior Member
    Messages: 248

    Did you put gas in it. I have a couple 7.3 and once one of the guys screwed up and put gas instead of diseal and it ran just as you described. Something to check. They do run on gas, but they run like crap.
  5. stroker79

    stroker79 2000 Club Member
    Messages: 2,802

    Are you sure the oil level is full and the oil is good? The engines MUST have good oil and be full otherwise they run like crap. Another thing to check is the IDM sensor/module
  6. FordFisherman

    FordFisherman PlowSite.com Addict
    from 06611
    Messages: 1,593

    I would get it scanned to see if its throwing codes- you need a good scanner for this. Also check the basics; is the HPOP resevoir full? Could be a number of things. Try thedieselstop.com for more info/ help. Those guys know alot.
    Last edited: Jan 13, 2010
  7. Darkness

    Darkness Junior Member
    Messages: 6

    Nope, havent done that one yet.
    Not sure at all but I will get the oil changed this weekend. Where/what is he IDM sensor?
  8. Darkness

    Darkness Junior Member
    Messages: 6

    Im a diesel noob. I have worked/built 4.6 and 5.4s into 1k HP motors but diesel is a whole now play ground to me. HPOP(high presure oil pump?) Where is the resevoir?

    I dont think I said that once I get into the gas, the truck has plenty of power and seems to run fine, it just runs really rough at or near idle.
    Last edited: Jan 13, 2010
  9. go plow

    go plow Senior Member
    Messages: 322

    mine did the same thing, turned out i got a bad batch of fuel,it had alot of water in the tank... i would put some power service in it and drive it for a while it should clear up, when it happened to me i thought the worse too....mine stalled, ran on 3 or more cylinders, stalled every 1/2 mile..,mine also started very hard, one day i had to charge the batt. twice by the time i got her running.....
  10. 01SMOKINSD

    01SMOKINSD Junior Member
    Messages: 29

    I had a very similar thing happen to me, turned out to be the left under valve cover harness came unplugged and i had actually lost all 4 cylinders on that side. Only took me about and hour to pull the valve cover, put a couple small zip ties in the connector and reinstall the valve cover. Becareful to check for leaks when done though. Good luck.
  11. 7.3 Plower

    7.3 Plower Senior Member
    Messages: 221


    Underneath the decorative cover is what looks like a large metal box. That is the hpop reservoir. On the side closest to the front of the truck on the driver side is a little threaded plug you can remove with an allen wrench. The oil level should be pretty close to the top of the reservoir although I am still inclined to believe it is a problem with your uvch.
  12. damian

    damian Senior Member
    Messages: 330

    dont waste your time fumbleing around the engine compartment aimlessly. first thing to do is plug into it with a scan tool,do the key on engine off ,key on engine running,and cyl contribution tests.this will tell you wich direction to go in. if you have high pressure oil issues it will show as a code,if you have an injector harness coming loose or a short at the drivers side valve cover it will throw a code for an open\shorted injector and tell you wich one.if you dont have any money,have a shop scan and run the tests,give you the results,get the diagnostic info for the codes at auto zone or some chain auto store that sells all data and go to it.you can go broke guessing.good luck
  13. snowandgo

    snowandgo Senior Member
    Messages: 143

    Could also have a sticky backpressure valve or a plugged backpressure sensor tube. It will open up at higher RPM, letting the engine run OK there.
  14. ajslands

    ajslands 2000 Club Member
    Messages: 2,033

    how would you have white smoke on a cold start?? shouldent it be blue