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Thread: Tee fitting at the fuel tank bung?

  1. #1

    Default Tee fitting at the fuel tank bung?

    Can I use a "tee fitting" at the "fuel tank bung" currently installed on my tank - so I can use the same bung fitting for supplying the EFI and for my N2O?

    I currently have one 8AN bung fitting welded to the bottom of my fuel tank. This currently feeds my carb and my N2O Cheater system. I run a single line from the Holley Fuel pump which is also located at tank to the engine compartment where that line splits to two pressure regulators to feed the carb and one for N2O. Now that I'm installing the Atomic EFI, I will need to use that bung for the EFI fuel line.

    Question 1. Can I put a -8 "tee" fitting on that fuel tank bung and then have the EFI fuel line feeding off one side and the N2O system feed off the other side? The N2O system would still go to the Holley pump mounted at the tank location. and the EFI line would go to the EFI fuel pump which would be located at the tank too.

    Question 2. I have the return style fuel system. The instructions (the "Note") for the Atomic EFI says to set it up as "Non-PWR with Regulator". Is this just for the initial setup and testing - or is it recommended that I leave it at this setting? Because the "PWM with Regulator" sounds like a more desirable setting (quieter, cooler).

    Fuel Pump Type: There are three selections for the fuel pump system. Select the system that you are using on your vehicle.
    • Pulse Width Modulated: This selection is used only when running a returnless fuel system with NO regulator.
    Non-PWM with Regulator: This selection is used when running a return style system with a regulator.
    PWM with Regulator: This selection is used when running a return style system with a regulator. It will run the pump at 50% duty cycle at idle producing quieter pump operation and will increase a duty cycle of 100% as the throttle and injector load increase.
    Note: It is recommended that you use Non-PWM with a regulator when setting fuel pressure as the PWM setting may decrease fuel pressure slightly at idle depending on the pump used.
    Question 3. Can I dump the return fuel into the top of fuel tank (just a bung installed in the fuel level sender plate) or do I need to run an internal hard line from the bung at the top of tank to the bottom so return fuel doesn't aerate the fuel in tank too much by dumping in at the top?

    Question 4. On the Distributor advance "lock out" instructions is says "pull distributor remove gear... "except Ford". I have a Ford (MSD 8477 distributor). Do I need to remove the gear on my Ford distributor? What is this exception?

    EDIT: 8AN not 6AN
    Last edited by countrybumkin; 10-19-2019 at 05:33 AM. Reason: correction

  2. #2

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    Is this forum inactive now? I thought by now there would be at least one reply by the mod.

  3. #3
    Join Date
    Dec 2009
    Location
    Connecticut
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    Call MSD Atomic EFI Tech Service at (915) 855-7123. MSD technicians are available from 7:00 a.m. to 5:00 p.m. Monday - Friday (mountain time).
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 11.8:1 comp, TFS R-Series intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 160A 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, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, M4602G aluminum driveshaft, FRPP 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 tires.

  4. #4

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    Okay. Thanks for posting the contact info.

  5. #5
    Join Date
    Dec 2009
    Location
    Connecticut
    Posts
    22,976

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    You're welcome.
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 11.8:1 comp, TFS R-Series intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 160A 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, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, M4602G aluminum driveshaft, FRPP 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 tires.

  6. #6

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    I spoke to MSD tech, and I will summarize the answers here in case anyone else comes along with the same questions.

    I asked about using the Tee fitting (-8AN out of tank then reducing that to two -6AN connections for MSD and Holley pumps) and he said using a "tee" at the tank bung is not a problem. So I'll run one side of Tee to MSD High-pressure pump and the other side to my Holley Red pump (low pressure pump for N2O).

    Also, on my question about dumping the return fuel directly into the top of tank (with no tube going to bottom to prevent aeration) he said it should not be a problem.

    Lastly, regarding the setting: "PWM with Regulator" or "Non-PWM with Regulator", he said he prefers the "Non-PWM..." but I can/should try it both ways. That response was not as instructive as I expected, but that's okay.

    I think the "PWM with Regulator" setting would be better as it says the pump will run at 50% duty cycle at idle and therefore run quieter and cooler. So that's what I'm going to try first.

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