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Backfiring out the pipe on decel

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  • Backfiring out the pipe on decel

    I've got my scout tuned pretty well from what I can tell. I run a 2d holley system and i'm having difficulty with it backfiring out the tailpipe on deceleration. i think i may have an exhaust leak on the passenger's side. how much would this affect the issue? and yes, the decel (also cold start) solenoid functions properly.

    jason

  • #2
    Ding ding ding...

    I think i figured this issue out. The manifold that contains a one way valve connected to the air rails on my scout has a leak in it. Upon deceleration it sucks in air and causes a backfire. Curious if anyone here has a good method for entirely removing the air rails. My pump is currently removed and there is a heater hose connecting the two air rails together to prevent them from sucking in mass amounts of air through the one way valve.

    I figure the air rail threads are of the NPT variety about 1/4"? Any help would be appreciated.

    Jason

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    • #3
      most of the ones I have seen just have pipe plugs in them.
      If it the ones sticking out the top of each exhaust port.
      Bill USN-1

      COMMITED TO TEACHING PEOPLE THE "PROPER" WAY TO EFI
      HAMILTON FUEL INJECTION
      May be the answer to all your fuel injection needs!
      Learn to do it right.

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      • #4
        I think your right about the exhaust leak causing your backfire, it has happened many times before but usally with a rich running carburator?
        Is that Holley system you have a closed loop?
        [CENTER]1994 Buick RoadMaSSter Estate Wagon LT1/4L60E. White and Woodgrain Sleeper...PCM 16188051 With SS/V4P/Custom Tune! WOT 12.9 AFR!

        1990 Chevy Suburban Silverado 5.7L 2wd ECM 1227747 HiWay Lean Cruise 18.5 MPG and 12.5 to 1 AFR at WOT!

        1972 IH 1210 Isky Cammed Balenced 345 4 speed PCM 16197427 Project!

        [SIZE=3][B][URL="http://www.gearhead-efi.com/"]GearHead-EFI.com[/URL] EFI Conversions and Chip Tuners![/B][/SIZE]
        [B]May be all you need to know about EFI![/B]

        and I still help local JustIH members (for fun) free! :cool: [/CENTER]

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