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Thread: Needle & Seat

  1. #1
    Senior Member RACING JUNKIE
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    Needle & Seat

    Here is my brilliant luck: I installed a new fuel pump & lines regulator, etc... I go to start the car for the first time & hit the FP toggle, it fires up & dies in about 10 seconds. I shut off the pump. I hear "trickling"... like a dripping sound. Not sure, I pull the air cleaner, pull the front bowl off & inspect the PV... it was fine. Then I hit the toggle again w/ the air cleaner off & watch the carb (950 QF) & I see fuel PUKING out of the front vent/tube on the primaries. I had dumped a TON of fuel down that poor carb!! Pulled the needle & seat, it looked fine, it was sealing & moving like it should. Put it back in the carb & the problem went away. Apparently it was stuck & that is where the fuel goes when it is stuck. (It is a BP system).

    Is this just a fluke??? Maybe it sat too long w/o being ran? Had it a 7PSI at the time. Should I replace it (needle & seat) even though this carb is fairly new?? Probably need a new oil change now... there is 100.00 bucks gone in a flash. Scoot
    "I would walk through hell on Sunday before I fear the enemy"

  2. #2
    Senior Member RACING JUNKIE TheRabbit's Avatar
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    It more than likely was a piece of trash or just seized. All kinds of small pieces of trash including foam from the fuel tank end up in the carb. You may want to clean the tank and flush all the lines real good to make sure nothing else in it.

  3. #3
    Senior Member DYNO OPERATOR
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    needle and seat

    Besides a 100 mesh stainless element filter before the electric pump to protect it, I run a filter after the pump with a finer paper element to protect the carb.
    If you look at Aeromotive tech section it shows they recomend that too.

  4. #4
    Senior Member RACING JUNKIE
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    What? A stuck needle & seat on a Holley?? :shock:
    Well blow me down.....I aint never seen that before! lol :lol:

    I suspect a tiny peice of rubber from one of the hoses or some other peice of thrash got hung in there and when u took the needle & seat off, it fell out, it happens.

    Anytime you work on the fuel system be ready for something like that, I always have a helper looking at the carb when I first prime it up, just a expensive learning curve Rigsby.

    I too run a pre-filter and a post filter.

    Cp
    ***IN GOD WE TRUST***

  5. #5
    Senior Member RACING JUNKIE
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    If you ran the SS Braided hose then you should have(if you didn't) ran a few gallons of fuel through the line with it unhooked from the carb or regulator to wash out any shavings from cutting the hose. JMO

  6. #6
    Senior Member DYNO OPERATOR
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    Quote Originally Posted by Tod74
    If you ran the SS Braided hose then you should have(if you didn't) ran a few gallons of fuel through the line with it unhooked from the carb or regulator to wash out any shavings from cutting the hose. JMO
    X2

  7. #7
    Senior Member RACING JUNKIE TheRabbit's Avatar
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    FYI. I spent some time talking to a MagnaFuel rep at the PRI show. He said they don't recommend putting a filter before the pump. It causes the pump to work way harder than it was intended. Makes it draw too many amps especially if it gets clogged up. Makes sense, but I still have a BG filter attatched to mine. I just don't like the thought of no filter before the pump. These pumps are made to push fuel not pull it through any kind of resistance.

  8. #8
    Senior Member RACING JUNKIE
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    I hate being a newby sometimes.... these are expensive mistakes!!! I thought I did a pretty good job too. I used all A/N, All SS hose, used a painless wiring/relay kit, etc... only to have a quart of fuel PUKE down into the pan as my end result. I could open a "AN fitting store" at this point...

    Wabbit: I have a new Mallory fuel filter very close to the tank. I managed to do it all gravity fed to the pump. I installed one filter is all. I thought about a second, (I do have a 8AN inline filter @ home), but I thought it would be too excessive. It is a return line system too. I hope it all woks out (I still have not driven the car w/ the new fuel system.

    The other thing I noticed is that the insulator pad for the pump is not enough to keep it as quiet in my opinion. It cannot be heard when the car fires up though.
    "I would walk through hell on Sunday before I fear the enemy"

  9. #9
    Senior Member DYNO OPERATOR
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    needleand seat

    When doing the initial pressure test on the fuel system, like said above, run some fuel thru all the line up to the carb to a catch can. If it is a Holley with sight level screws, remove them before pressurizing the carb. If the needle and seats are misadjusted too high or get stuck, the fuel will usually all come out the sight plug holes without going up and over the vent tubes and into the carb and engine. If there are no sight level plugs, put hose over the vent tubes and route away from the carb to a catch can.

  10. #10
    Senior Member RACING JUNKIE
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    Re: needleand seat

    Quote Originally Posted by markdunlap
    . If the needle and seats are misadjusted too high or get stuck, the fuel will usually all come out the sight plug holes without going up and over the vent tubes and into the carb and engine. If there are no sight level plugs, put hose over the vent tubes and route away from the carb to a catch can.
    Thats a pretty good idea right there ^

    Cp
    ***IN GOD WE TRUST***

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