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Thread: 1994 GM P-30 TBI ?s

  1. #1
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    1994 GM P-30 TBI ?s

    I own a 94 Southwind Storm motorhome (454 TBI w/4L80E) and thus far she has been very reliable. I purchased it back in Sept 2014 with ~45K on the odometer. I'm now at ~74K. I'm going to pull and rebuild the TBI here soon and was wondering if there is anything I should do while I have it off? This will just be a basic rebuild (gaskets, o-rings). I purchased a Delco rebuild kit for it Rochester 220 I believe. It has never been rebuilt and currently runs great. Once at operating temp it idles at 800rpm steady in Park. I also replaced the large AC condenser w/integral oil cooler this past Sept (leaking oil cooler) and clean out the radiator tube fins hwile the cooler was out of the way. If interested you can see the work I did here:https://www.gmt400.com/threads/conde...-cooler.59140/

    One other thing...

    Anyone know of the (ISC) on the 454 trucks? It speeds up the idle at first start. Was wondering if anyone knows where to source one. My current one is still functional but was wondering in the event it became non functional then what? It is the item in the following thread on the left...
    https://www.gmt400.com/threads/help-...-please.41025/

    Part number -
    GM 17084953 Idle speed control actuator


    Each year I make up a list of stuff to replace (due to age). Thus far I've replaced the following items using Delco parts...

    1. TPS
    2. IAC
    3. EGR (Linear)
    4. PCV
    5. Idle control speed solenoid
    6. Purge valve
    7. VSS sensors
    8. Aux fan motor
    9. Plugs
    10. Wires 8.5mm ceramic
    11. Shift solenoids A & B
    12. Alternator
    13. Radiator cap
    14. Upper & lower radiator hoses
    15. By-pass hose
    16. Engine - frame ground braid cable
    17. O2 sensor (single wire)
    18. Belts (3)
    19. MAP sensor
    20. Ignition coil
    21. Pick up coil (rebuilt distributor)
    22. Cap
    23. Rotor
    24. ICM
    25 T-stat (195F)
    26. Rebuilt driveshaft
    27. Front hubs
    29. Ceramic pads
    30. Master cylinder
    31. Trans wire harness (internal)

    Much appreciated everyone

    Not sure why the pic of RV is upside down LOL!
    Attached Images Attached Images
    Last edited by udidwht; 3 Weeks Ago at 08:02 PM.
    1994 GM P-30 Southwind Storm 28ft
    454 TBI w/4L80E trans
    VIN #1GBJP37N4R3314754

  2. #2
    Super Moderator dave w's Avatar
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    I prefer having the original injectors cleaned / serviced vs. aftermarket new replacement injectors.

    I recommend the services of Mr. Injector: https://www.mrinjector.us/

    I've had good results with remanufactured injectors from GB Remanufacturing: https://www.gbreman.com/

  3. #3
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    Much appreciated, when I get the TBI off I'll pull the numbers off the injectors. I'd indeed prefer to have them serviced as opposed to buying unknown ones.

    Any recommendations on a fuel pressure gauge set up that connects to TBI?
    1994 GM P-30 Southwind Storm 28ft
    454 TBI w/4L80E trans
    VIN #1GBJP37N4R3314754

  4. #4
    Super Moderator dave w's Avatar
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    Quote Originally Posted by udidwht View Post
    Any recommendations on a fuel pressure gauge set up that connects to TBI?
    I recommend "Not Installing" a fuel pressure gauge setup. Under hood temperatures will affect fuel pressure gauge accuracy.

    I recommend modifying or buying a TBI fuel inlet fitting to allow easier access to check fuel pressure, if / when needed to check fuel pressure: https://marine-performance-parts.com...843505774.aspx

    tbifuelpsifitting.JPG

  5. #5
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    Quote Originally Posted by dave w View Post
    I recommend "Not Installing" a fuel pressure gauge setup. Under hood temperatures will affect fuel pressure gauge accuracy.

    I recommend modifying or buying a TBI fuel inlet fitting to allow easier access to check fuel pressure, if / when needed to check fuel pressure: https://marine-performance-parts.com...843505774.aspx

    tbifuelpsifitting.JPG
    Appreciate that. I just picked up that adapter. I take it it replaces the inlet fitting on the TBI? Of the (2) fittings which is the inlet? Can't recall off the top of my head if they differed in size. I do know that both come from the rear side go into the TBI (left/right). I've go a pic I'll post up.
    1994 GM P-30 Southwind Storm 28ft
    454 TBI w/4L80E trans
    VIN #1GBJP37N4R3314754

  6. #6
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    Here's a link to a pic of the engine...

    https://www.dropbox.com/s/ow3nt7k4hf...B1%5D.jpg?dl=0

    I'm going to say the one on the right. Take that back looking at the pic closer it appears the inlet is on the drivers side.
    Last edited by udidwht; 04-16-2023 at 04:20 AM.
    1994 GM P-30 Southwind Storm 28ft
    454 TBI w/4L80E trans
    VIN #1GBJP37N4R3314754

  7. #7
    Super Moderator dave w's Avatar
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    Usually the inlet fuel line is 3/8" and the outlet (return) is 5/16". Likely the inlet fitting Will Not Fit the outlet fitting.

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    I add a schrader valve so i can use a regular automotive fuel gauge. I always thought having a gauge permanently mounted under the hood was a bad idea. I've also heard that heat affects the accuracy as well

    https://www.dieselorings.com/schrade...-1-8-mnpt.html
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    Quote Originally Posted by tayto View Post
    I add a schrader valve so i can use a regular automotive fuel gauge. I always thought having a gauge permanently mounted under the hood was a bad idea. I've also heard that heat affects the accuracy as well

    https://www.dieselorings.com/schrade...-1-8-mnpt.html
    Great! I'll pickup the schrader valve as well. Gone this far I may as well pick up a fuel pressure kit. Any recommendations?
    1994 GM P-30 Southwind Storm 28ft
    454 TBI w/4L80E trans
    VIN #1GBJP37N4R3314754

  10. #10
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    i've had an OTC one for almost a decade p/n 5630. only thing i don't like it about it is it didn't come with a carrying case.

  11. #11
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    Quote Originally Posted by dave w View Post
    I recommend "Not Installing" a fuel pressure gauge setup. Under hood temperatures will affect fuel pressure gauge accuracy.

    I recommend modifying or buying a TBI fuel inlet fitting to allow easier access to check fuel pressure, if / when needed to check fuel pressure: https://marine-performance-parts.com...843505774.aspx

    tbifuelpsifitting.JPG
    FYI...that fitting leaked at the threaded areas on both the plug and the fuel schrader valve. Applied Permatex 2 prior to install. Reinstalled the OE fitting no leak. Contacted CFM for refund.
    1994 GM P-30 Southwind Storm 28ft
    454 TBI w/4L80E trans
    VIN #1GBJP37N4R3314754

  12. #12
    Super Moderator dave w's Avatar
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    Quote Originally Posted by udidwht View Post
    FYI...that fitting leaked at the threaded areas on both the plug and the fuel schrader valve. Applied Permatex 2 prior to install. Reinstalled the OE fitting no leak. Contacted CFM for refund.
    Thank you for sharing your experience with the CFM fitting.
    Last edited by dave w; 05-03-2023 at 04:14 PM.

  13. #13
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    Anyone know of a well made fitting that won't leak?
    1994 GM P-30 Southwind Storm 28ft
    454 TBI w/4L80E trans
    VIN #1GBJP37N4R3314754

  14. #14
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    Quote Originally Posted by udidwht View Post
    Anyone know of a well made fitting that won't leak?
    did you make sure the small plastic seal was on the end?

  15. #15
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    Quote Originally Posted by tayto View Post
    did you make sure the small plastic seal was on the end?
    Did indeed. The leaks were at the fitting threads.
    1994 GM P-30 Southwind Storm 28ft
    454 TBI w/4L80E trans
    VIN #1GBJP37N4R3314754

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