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91 7.3 died won’t restart

Discussion in '911 Diesel Down!' started by Molly, Mar 13, 2020.

  1. Molly

    Molly Registered User

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    The background: took it in for a brake job, never had an issue with non-start before.

    The mechanic called me and said they can’t get her going. If they spray her, they can get her to turn on, but she dies shortly after. They took apart the HPOP, cleaned it out, put it back, and she ran for a bit. They considered it fixed. While it was there, I also had them drop the gas tanks and she got new shower head, new pickup tubes in both tanks, and new brake lines and hardware.

    They bent a breather tube and I had to take it back.

    Anyway, she ran 300 miles approximately, died on me in traffic, and refuses to restart. She cranks, but won’t turn over. There is diesel on top of the filter which may or may not be relevant to the issue, and I’m at my wits end.

    there’s a position sensor I want to try to change, but for the life of me I can’t remember what it’s called. It’s not the Throttle Position Sensor. It’s a sensor on a wire, plug and play part, and can cause non-start issues in these trucks.

    obviously, I have no formal training and this post sounds dumb as hell.

    but if you know the name of the part, or can tell me I’m an idiot and it’s something else, yay. Because she’s collecting wasps and I’d very much like to ruin their day and get her back on the road.

    Edit: I’m also aware that it could be air intrusion from them pulling and dropping the tanks repeatedly and not bleeding the lines, but I’d rather hear it from someone else first.
     
    Last edited: Mar 13, 2020
  2. gandalf

    gandalf Senior Member

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    You've got to tell us a bit more about the truck. Year? Model? Past problems? Condition, engine and batteries? You're more likely to get a usable answer if you give better information. Thanks.
     
  3. Molly

    Molly Registered User

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    91 7.3 F350, no past problems, besides needing a new oil pressure switch, radiator, and the seized caliper which initiated the brake job. Batteries are new, good condition, 300,000 miles between three owners.
     
  4. Va_Mike

    Va_Mike Full Access Member

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    If they dropped the tanks and now your having a starting problem that is presenting itself like air intrusion then they most likely didn't get some lines put back together properly. Also I am pretty sure only the Powerstroke's have a HPOP so if hey say they cleaned it I would be very suspicious as to what they actually took apart and cleaned if they even did?
     
  5. gandalf

    gandalf Senior Member

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    I believe Va_Mike is right. I don't think the '91 F350 had an HPOP. So far as I understand that started with the PowerStroke. The '91 is an IDI engine. If they claim they worked on the HPOP, have them point to it, touch it, and take a picture. Most of us understand pictures.

    They dropped both tanks and replaced the pickup tubes in both? If they didn't purge the air from the fuel lines properly that would be a problem. OTOH, if it drove for 300 miles with no problem, then, perhaps, sat over night, and had problems starting, it sounds like you may have a significant air leak in the fuel system. You can kill your new batteries trying to purge air in the fuel lines. Try cranking for a couple seconds, then push in the pin on the schraeder valve (located on the side of the fuel filter--looks like a tire air valve). If you get air coming out that would reinforce the air leak suspicion.

    IF you want to try cranking the engine to purge air, crank for about 20 seconds, then let the starter cool for 2 or 3 minutes. Continuous cranking for longer periods will overheat the starter and kill it.
     
  6. Molly

    Molly Registered User

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    Solved. Air intrusion from punctured fuel line. Wasn’t big enough to leak, but big enough for air to squeak in. Replaced, she’s running good now.
     
  7. Va_Mike

    Va_Mike Full Access Member

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    That's great news!
     

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