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Thread: 5.3 LM7 Terminator X - starts then stalls.

  1. #21
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    Quote Originally Posted by bpray9223 View Post
    Injectors: Stock truck injectors, Multec 2 (PN 25320288).
    Is there any way to definitively rule out clogged injectors as a culprit?
    Have these injectors been cleaned & flow checked?
    If not, and they're out of that engine at that mileage, I'd be very suspect of their performance. Only takes a couple of these, to make things difficult.
    A case in point: I cleaned, and installed a set of those injectors for a friend. He has not driven the car, since last December ('55 Chevy/LQ4 combo). Engine will not start. Injectors stink to high heaven. They're now on the bench for cleaning. The tank is full of 93, and Stabil conditioner, for ethanol fuels.
    Other questions: Do you see the fuel psi staying up, while the engine does run?
    And, yes. I'd be suspect of the VE being over 100%.
    Last edited by Chuck L.; 09-07-2020 at 03:10 PM.

  2. #22

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    @Chuck L.: Excellent points all around. If the injectors are stuck, then the ECU will be adding extra fuel (increasing the IPW) to achieve the desired AFR and the flow numbers and the VE% will appear to be artificially high. There is no way that a stock LS 5.3L needs 9-10 lb/hr of fuel at idle. My guess is it should be half that.

    The Fuel Flow and the VE% numbers are calculated based on injector size, fuel pressure, and the injector pulse width. If the parameters in the System ICF are off, or the injectors are not flowing what they should be, the Fuel Flow and VE% numbers will be off as well. Andrew

  3. #23
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    In datalog #4 it starts to go lean and it's still getting 10 lbs/hr of fuel. That's probably enough to keep it going. Are your fuel injector settings correct? And have you verified your fuel pressure as it's running? Here's a Global File and startup datalog from a buddies LS2. Just in case you wanted to make some comparisons.
    Attached Files Attached Files

  4. #24

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    @Chuck L.: The injectors are original and have not been cleaned/flow tested. The engine sat approximately six months before starting again, so to your point, these might be causing my issues.

    I'm about to pull the trigger and just buy a new set of injectors to see if that solves the issues. It's the only thing that makes sense to me as the engine idled and ran fairly well during the first few test fires. I'm thinking enough particulate made its way through the fuel rail and clogged the injectors from sitting for a while and that could explain the "sudden" change in behavior.

    @81 TransAm: I believe my injector settings are correct. I have the GM 25320288 injectors selected, 60 psi "Rated Fuel Pressure", and 60 psi "Actual System Pressure". Is this not correct? Should I not have "Actual System Pressure" pre-populated in the Config File without a discrete measurement taken from a gauge?

    I apologize if this is a silly question, but how would I go about measuring/monitoring my fuel pressure while engine is running. I do not have a fuel pressure gauge. Is the Holley ECU capable of reading that somehow using an existing sensor? As a reminder, I still have the factory "return style" fuel rail and vacuum referenced fuel pressure regulator.

  5. #25
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    Quote Originally Posted by bpray9223 View Post
    I believe my injector settings are correct. I have the GM 25320288 injectors selected, 60 psi "Rated Fuel Pressure", and 60 psi "Actual System Pressure". Is this not correct?
    Not correct. Those injectors are rated at 3 bar, (43.5 psi). When run at 4 bar, (58 psi), they have a higher flow. I use 60, and set the regulator to that value. It's easier to remember, for an old guy!
    Go to the "System ICF", & input the rated as 43.5, and it will calculate the flow at 58. The program will then use that flow rate for the operation of the engine.
    Example: At 43.5, the injectors is rated at 24.7 PPH. At 60, it's 29 PPH.
    Of course, a dirty injector is a no go. I see new, genuine GM injectors on the bag for right prices. Just BE SURE you get all the specs for whatever you buy.
    Last edited by Chuck L.; 09-08-2020 at 06:05 AM.
    Injector Inspector
    USAF 1960-1964
    Drag racing since 1955

  6. #26
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    The system is capable of reading fuel pressure if you add a fuel pressure transducer. However, the system does not use this input to calculate fuel flow, it's for monitoring purposes only. Fuel pressure is something you must know before you set your injector settings.

  7. #27
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    http://forums.holley.com/showthread....ents-Read-This (Initial Checks & Adjustments - Read Step #2)
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS T/W 11R 205 heads, 232°-244° duration/.623" lift/114° LSA camshaft, 12:1 C/R, TFS R-Series FTI ported intake, BBK 80mm T/B, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 200A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, -6AN fuel system plumbing, Walbro 255 LPH pump, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/3000 RPM converter, B&M Hammer shifter, FPP aluminum driveshaft, FPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 M/T Street Comp tires.

  8. #28

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    @Chuck L.: Wow, can't believe I missed this! I'll adjust the following in the config:
    --Injector Rated Fuel Pressure: 43.5 psi.
    --Actual System Pressure: 58 or 60 psi (before doing this, I'll measure the actual fuel pressure from the test port on the fuel rail and engine-off/key on. I have the Walbro 450 pump. https://walbrofuelpumps.com/450lph-w...0267.html.html)

    In the meantime, I did buy a set of 8 "new" (refurbished) injectors from a reputable source on eBay, along with a 10 Micron Fuel Filter (I currently have a 40 Micron). Both of these should help if the adjusted fuel pressure settings do not solve my problem.

  9. #29

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    Actual System [Fuel] Pressure is with engine off and fuel pump running. Andrew

  10. #30
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    Also check the fuel pressure when the engine starts. You may have a flow problem that happens when it's running.

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