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Engine shutoff and dragging start at normal temps

Discussion in '6.9L IH & 7.3L IDI Diesels' started by GreggH, Sep 15, 2020.

  1. GreggH

    GreggH Registered User

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    So... I need some help diagnosing my truck.

    upload_2020-9-15_14-35-27.jpeg
    ‘94 f350 idi N/A but added a turbo

    I play with this truck in the mud. The last time I had it out I got stuck to the bottom of the cab, which put the exhaust under water. The truck stayed running but once I was pulled out (within 10 mins) I rev’ed her up just to clear any water in the exhaust. After it rev’ed up and came back down in RPMs, she died.(engine and most of truck completely out of water after being pulled out). So I tried to start it back up and it had a really sluggish, dragging turnover. Not the speed of turn over as normal. Messed with it for a while but ended up just pulling it back to the camp site for the night.

    Next day, I start messing with it. Engine turns over and starts right up, no problems. I let her run for a bit while I’m cleaning a little bit of muddy water out of the intake duct (did not make it all the way to the air cleaner). While it’s sitting there idling just normal, all of a sudden she just dies. I go back to try to start her back up and it does the same sluggish/ dragging start with no luck for firing off so I leave it to mess with later.

    Second day, go out and same thing. Fires right up. So I’m looking at the gauges a little more. I installed a pillar cluster with fuel pressure pre-filter (more about this in a sec), EGT, Trans Temp, and Boost, along with the dash gauges of oil pressure, coolant temp, amp, etc. All looks normal...

    So for the fuel pressure, for some reason over the years, I have not had very good luck with the mechanical fuel pumps, them always going out and the truck takes a good bit of cranking to fire up each time if at all in the cold with a block heater on. So I started running a cheap in-line fuel pump from the parts store. It fire up quick every time. But the parts store el cheapo ones don’t last long so after reading recommendations on here, I bought a Facet filtered inline fuel pump... has been working great. It is wired up to run constantly. During all this I have maintained good fuel pressure (5psi +/-) pre-filter. Read that the IP only needs 1-2psi so plenty of pressure. Before anybody asks, no I have not installed any kind of pressure reg.

    Btw, the batteries are fairly new and I also have tried putting a jump box in addition to them just to eliminate the low charge.
    Have heard of starters dragging once they warm up but don’t feeling like that’s it.

    So I am leaning towards the IP is bad. Am I correct in thinking this?? Ya’ll have way more experience on this group than I do with these engines, I have just learned as I go. Any help is appreciated.

    Thanks
     
  2. GreggH

    GreggH Registered User

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    So for such a long post...
     
  3. gandalf

    gandalf Senior Member

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    I don't believe that your IP has anything to do with the starter motor cranking slowly. The starter merely turns the engine over, with or without fuel.

    You say you had mud and water up to the belly of the truck, up to the floorpan. That would mean that you got the starter very wet, you got the FSV very wet, you got any under body electronics wet. (FSV=fuel selector valve) My best guess is that the starter is suffering from that. Check all cable connections on the starter, and check the ground. Pull the ground cable and be sure you've got a good contact surface. Let the underside dry thoroughly. That may take time. And, of course, you may have pooched the starter.
     
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  4. IDIBRONCO

    IDIBRONCO IDIBRONCO

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    I agree with the starter. I had a similar issue after I got too far into a snow drift and had to back out. It started just fine after that, but the next morning, nothing. Later that afternoon, it had warmed up to the 30's. The truck started right up. I drove it down the road a ways to get the starter good and hot (from engine heat) to dry it out.
     
  5. BR3

    BR3 Full Access Member

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    Also, did you check your alternator output/ battery voltage? As well as the other connections? May just have a hot ground main lead working loose since it got buried or something. Bad grounds do wired things
     
  6. GreggH

    GreggH Registered User

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    Everything I understand, these motors will basically run without battery or alternator voltage/current. U may not have power to anything but the motor itself will run with even just minimal or no power to keep a fuel valve open I guess in the injection pump? (and have unfortunately tested that theory once). So I can’t see it being a power issue but I will check it, just to eliminate it for sure. Like I said, with the engine cold it turns over strong and starts up without any issue.

    as for the starter, I could definitely see it being nasty inside and understand it being the problem if it dragged starting all the time, but it doesn’t when cold. It would also not explain why the motor just dies once it warms up.

    The reason I said IP is I believe I read on here somewhere or might’ve been another site, about them heat locking or almost vapor locking sometimes when going bad. I don’t know as I don’t have any experience in IP’s going out or issues with them, yet.
    I also had an issue at the gas station on the way out there, where after driving a couple hrs, stopped to get fuel, and when I went to crank it back up it did not want to start... after Making sure I had good fuel pressure and cranking, sitting, cranking, sitting, cranking it finally fired up. Felt like 5 minutes or more. And this is with a clean chassis.

    what are some symptoms ya’ll HAVE had when the IP starting going out?
     
  7. BR3

    BR3 Full Access Member

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    You're right it is only one wire, but bear in mind that one wire is enough.the fuel shut off solenoid is what needs power to keep the engine running.

    Bear in mind too that as heat increases so does every negative aspect of anything electrical, like connection issues,resistance, anything that can cause problems. I had a truck with a 460 in it do pretty much exactly what you're talkin about. Granted that is a gas motor but as far as the slow cranking on your idi. it ended up being a loose negative connection at the battery.

    As for the heat soak your suspecting, while anything is possible, what normally happens with an IP heat soak issue is you fire up your truck cold in the morning, it starts fine ,it runs fine,y park your truck after it's gotten hot, let it sit for an hour it cranks fine but won't start. You had mentioned slow cranking speed, which is what makes me think it's not an IP heat soak issue. What happens with ip heat soak issue is that the pump rotor doesn't expand as fast as the housing causing the necessary clearance to become too large. So the cranking occurs normally it just doesn't get any fuel pressure. If you still suspect heat soak dump a gallon or two of water on the ip next time it happens and see if it starts
     
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