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Thread: 1st Dragstrip runs of 2017, going VERY LEAN at WOT.

  1. #1
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    Question 1st Dragstrip runs of 2017, going VERY LEAN at WOT.

    Looks like my Tanks Inc. 255 LPH setup is not keeping up with demand, which is kind of unusual, since it did last year. Datalogs show as lean as 18:1 midway through high gear, and injector "duty cycle" well over 100%. I guess because it was trying to add enough fuel to NOT be way lean? Commanded AFR was 12.5, but actual was higher, sometimes MUCH higher and climbing with RPM. Datalogs said as high as 18:1, so I'm lucky to not have a blown head gasket.

    I use a Tanks Inc setup, with their Walbro 255 LPH pump, advertised to support 630 HP at 13.5 volts. My car NEVER goes below 13.8. I use all -6 and/or 3/8" lines for feed & return, and had well over a 1/2 tank of fuel. Any suggestions, or feedback?

  2. #2
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    Well, was the fuel pressure dropping?
    May God's grace bless you in the Lord Jesus Christ.

    '78 BRONCO: 508" stroker, TFS heads, 11:1 comp ratio, Dominator MPFI & DIS, cold air induction, Spal dual 12" fans/aluminum radiator, dual 3" exhaust/Magnaflow mufflers, Moroso vacuum pump, Accusump, engine oil & trans fluid coolers, 100HP progressive dry direct-port NOS, A/C, LenTech Strip Terminator wide-ratio AOD/2500 RPM converter, 3:1 Atlas II, modified Dana 44/60-lockers-4.10s, hydroboost/4-disc brakes, ram-assist/heim joint steering, Cage long radius arms, traction bars, 4" Skyjacker lift, 35" mud tires

  3. #3
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    This could be as simple as clogged or dirty fuel injectors. Or it could be a pump failing. What fuel are you using?
    Have you checked your fuel filters to make sure they're clean and operating properly (not collapsed or falling apart).
    -Scott
    Don't forget to check out progress on my Race Car:
    Project Blasphemy - 8.07 @ 171
    Low 8 Second Street Car

  4. #4
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    Quote Originally Posted by Danny Cabral View Post
    Well, was the fuel pressure dropping?
    I do not have an external gauge...yet. The car ran flawlessly last year, so I really never saw a need for one. I've always just took a few quick glances at my AEM wideband gauge at about the 1000' mark and never saw anything to make me warrant an external gauge.

    Quote Originally Posted by S2H View Post
    This could be as simple as clogged or dirty fuel injectors. Or it could be a pump failing. What fuel are you using?
    Have you checked your fuel filters to make sure they're clean and operating properly (not collapsed or falling apart).
    I use 93 octane unleaded pump gas. The Sniper EFI has only been on the car since mid October with maybe a dozen runs and a couple hundred street miles.
    I hope it's not an injector issue. I have the in-tank 255 LPH Walbro that came with the Tanks Inc setup. It has seemed LOUD since Day 1 though. When priming it sounds like an old Holley Blue Pump.

  5. #5
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    There's never a good reason to not monitor fuel pressure or oil pressure.
    These are the two things that should ALWAYS have some sort of sensor on them.
    You can't diagnose a problem if you don't have the data to start with.

    My suggestion would be to get a 0-100 psi fuel pressure sensor installed on that thing, and then you can datalog it happening and figure out if it's fuel related or if it's somewhere else in the chain.

    P.S.: IF that tank has "foam" in it, I can almost guarantee you have either a clogged filter or clogged injectors. Anti slosh foam is a horrible thing, and often comes apart inside of the tanks.
    -Scott
    Don't forget to check out progress on my Race Car:
    Project Blasphemy - 8.07 @ 171
    Low 8 Second Street Car

  6. #6
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    The Tanks Inc tank is a stock look, EFI conversion tank with generic 255 LPH in-tank pump and stock type "sock" pre-filter. From there, I have -6 up to the engine, with a Russell EFI filter before it plumbs to the throttle body. If you can share any tips on connecting a pressure sensor that will read on the Sniper datalogs, I'm all ears. I had no idea that was even a possibility. This is a mid 11 second street/strip car, and right now just has the basic gauges. Tach, wideband, oil pressure & coolant temp.

  7. #7

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    There's three options for extra sensors, but they're grayed out for some reason. And I couldn't figure out how to enable.

  8. #8
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    I'll look around in the Sniper EFI software tomorrow, and see if I can even find it.

  9. #9
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    Custom #1, #2 & #3 in the Sensors screen. Evidently, it's not available yet.
    May God's grace bless you in the Lord Jesus Christ.

    '78 BRONCO: 508" stroker, TFS heads, 11:1 comp ratio, Dominator MPFI & DIS, cold air induction, Spal dual 12" fans/aluminum radiator, dual 3" exhaust/Magnaflow mufflers, Moroso vacuum pump, Accusump, engine oil & trans fluid coolers, 100HP progressive dry direct-port NOS, A/C, LenTech Strip Terminator wide-ratio AOD/2500 RPM converter, 3:1 Atlas II, modified Dana 44/60-lockers-4.10s, hydroboost/4-disc brakes, ram-assist/heim joint steering, Cage long radius arms, traction bars, 4" Skyjacker lift, 35" mud tires

  10. #10
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    Quote Originally Posted by Danny Cabral View Post
    Custom #1, #2 & #3 in the Sensors screen. Evidently, it's not available yet.
    I guess that will be in some sort of future software update, maybe?
    So, I'll probably just get a female to male -6 fuel pressure adapter.
    Like this: http://www.jegs.com/i/JEGS-Performan...00526/10002/-1
    And hopefully be able to use my fuel pressure tester that I use here at work.
    With the hood setup having no cowl, on a '71 Chevelle, the mounting options for a permanent gauge are simply not there.

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