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OBS With strange symptoms

Discussion in '7.3L Powerstroke Diesels' started by Bakersk896, Feb 20, 2021.

  1. Bakersk896

    Bakersk896 Registered User

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    Well today went just as expected. After leaving the store, the PSD died on me with no warning. It started back up and ran under load for about 100 yards then died again. Checked the fuel bowl and the fuel was pretty clean and the bowl was full. Drained the bowl some and pressure was good and started the truck up. It ran and got me to the gas station and was able to fill both tanks. Drove another 8 or so miles and made it almost home before it died again. It would not start again until I pulled it home about 15 minutes later. It acts like it is running out of fuel as if the fuel pump is failing which I have seen quite a few times in other trucks. My other fear is that the computer is failing due to sporadic check engine light flash and WTS light when the truck shuts itself off. Another detail that may be connected is that I have had an issue with my chip before. More specifically it was a bad connection made where the chip mounts to the computer. There are no codes being saved though.

    Truck details
    -1995 F-250 Ext Cab Long Bed 306k miles
    -7.3 PSD only upgrades include cold air intake and TS chip with Swamps Tune
    -E4OD rebuilt around 200k

    Recent Maintenance
    -Trans Filter and Fluid change 1k miles ago
    -Fuel Filter and bowl drain 1k miles ago
    -Oil cooler replacement 1k miles ago
    -Coolant flush and oil change 1k miles ago

    My first course of action is going to be removing my chip and attempting to drive. If identical symptoms continue then replacing the fuel pump with an frame mounted setup will be next. After that, i may be doing a computer swap. Anyone had this type of issue and fixed it? Nothing seems to be pointing me to anything specifically.
     
  2. greenskeeper

    greenskeeper Full Access Member

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    I doubt it's fuel.

    Sounds like the ignition is cutting out and you are getting the CEL and WTS lights as if the key was turned off and then on again.

    I'd definately remove the chip and see if the problem goes away. Could be the ignition switch if it still does it with the chip removed.
     
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  3. Bakersk896

    Bakersk896 Registered User

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    So I have a fuel pump on standby and a pressure gage ready for testing tomorrow. First step is startup and watch pressure until shutdown that way no variables are changed. If the fuel isn't stable or drops off prior to shutdown then we know its the pump or a leak. Then the chip comes out. If no change is seen then the ignition switch is getting changed. If the chip coming out makes the difference then chip and chip connection troubleshooting is my course. Thanks for the advice @greenskeeper
     
  4. Oledirtypearl86

    Oledirtypearl86 Full Access Member

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    Let is know I had a trick pull the same thing and everything checked out
     
  5. Double-S-Diesel

    Double-S-Diesel parts seller

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    possibly the fuel bowl heater shorting out, but not enough to blow fuse
     
  6. Bakersk896

    Bakersk896 Registered User

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    So I started the truck up today and got it up to temp while periodically checking fuel pressure. It’s good and steady. While under load the truck runs normal with no symptoms found yesterday. I did notice that after filling the front tank, it reads what looks to be a quarter tank over full. That leads me to believe I lost prime yesterday when it got down to around a quarter which would answer most of the issues I had but not sure it matches the CEL and WTS light acting strange. I’ve never shut a PSD down with the key still in run though to see what it would do. When the misses gets back from lunch with her friends we will go for a longer drive and see how it acts.
     
  7. Bakersk896

    Bakersk896 Registered User

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    Immediately after posting the reply above, I played with the key switch and with it still in run, moving it slightly back towards the neutral position but remaining in the run detent, the truck shut down and the CEL came on. @greenskeeper seems like you were right. The issue isn’t consistent so I’m going to replace both the key switch and ignition switch. I only have one key to this trucks ignition anyway.
     
  8. Bakersk896

    Bakersk896 Registered User

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    The answer has been found. The key switch and ignition switch were replaced taking about 20 minutes total and one less headache in the driveway. For anyone trying to replace the key switch, it may stick some after pressing the release detent and require a small amount of prying. The ignition switch on the column is extremely easy to replace and requires a torques bit and a 7mm socket. Thanks for the help all.
     
  9. Bakersk896

    Bakersk896 Registered User

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    Alright. This isn’t good. Truck is still acting up. It’s only when the truck is fully warmed up and has run for about 15-20 miles or more. It acts like it’s running out of fuel. The key switch was bad for sure but not the culprit of this issue. Now to pull my chip to see if that’s causing the headache. I’m afraid it might be fuel pump or worse. The CEL comes on still after shutoff but clears when the truck is restarted. My code reader won’t connect to this truck since it’s a 95 and not a 96. Any more suggestions gentlemen?
     
  10. gnathv

    gnathv Full Access Member

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    Check your fuel pressure when it dies. Mine did that to me and it was bits of fuel pickup from tank partially clogging lines. It would begin to lose power and eventually die. It would not restart immediately but if I let it sit for 15 minutes it would restart and drive normally until the pieces clogged the lines again. I blew air back to the tanks and cleared it. Then replaced pick ups. Worth checking. You can use tire gauge on filter head to check pressure, just wrap it in a rag to avoid shower.
     
  11. Bakersk896

    Bakersk896 Registered User

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    It starts back up within 30 seconds. After some thinking, it more seems like an electrical component is getting too hot due to an internal failure. It cools after 30 seconds or so and then runs for a minute or two then shuts down. After sitting for a bit while I’m in the office, it fully cools and will run for about 20 miles then act up. I also need to check my alternator output because by voltmeter is at the top end of the normal section near 18v. I know it’s not major but it does increase current flow and some electronics are voltage sensitive.
     
  12. Bakersk896

    Bakersk896 Registered User

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    Note to all by the way. 99% of scan tools will not read a 95 PSD due to federal law not requiring OBD II until 1996 and very few manufacturers starting it early. Ford is one that started in 95 with the PSD’s
     
  13. lotzagoodstuff

    lotzagoodstuff Supporting Member Supporting Member

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    Have you tried using Forscan? It seems to work well on PSDs, I have a 1995 and I had no issues connecting to my laptop with a $29 wireless dongle.
     
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  14. Bakersk896

    Bakersk896 Registered User

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    Got a new scanner on the way. Hope to got it works. Maybe it can help point me in the right direction.
     
  15. Bakersk896

    Bakersk896 Registered User

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    So my connector is In and my laptop is hooked up. This is the readings in getting. All other tests passed. Don’t mind the ECT. I think it reads it backwards for some reason. It is tracking with the the gauge though. This is at idle by the way.

    image.jpg
     

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