Engine trying to die after hard pull
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Engine trying to die after hard pull

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    Default Engine trying to die after hard pull

    I just installed an Aeromotive electric fuel pump for mySJ. Pump is rated for over a 1000 HP. It's on a 505 BBC with a 1050 Proformcarb (1/2" line). I have it regulated down to 8 PSI. I think the motormakes around 600 to 630 HP. Coming in to the dock, I ran it 4k for a few minsand went to around 5800 for a few sec's and let out all the way to an idle.Fuel pressure was at 6 PSI right after the pull but at idle it wanted to dieand I had to throttle it up a few times to get it to recover. Then when I wasloading it on the trailer, same thing; nothing else has changed and I put newplugs in over the winter.
    I will say that I will never run a mechanical pump on any boat I ever have again. After setting for a few weeks, it's nice to turn the key on and prime the system, pat the gas twice and your off. Beats the heck out of turnig it over and over again.
    What should I do? Less fuel pressure? More fuel pressure? What are you guysrunning?


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    LP-25.com Infomaniac's Avatar
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    If it wants to die at idle after being under power it could be several things. More than likely needs more air.

    Also to make sure a carb has plenty of fuel you can set the idle pressure to 7psi or so and give 12 -15 psi when under power.
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    Quote Originally Posted by Infomaniac View Post
    If it wants to die at idle after being under power it could be several things. More than likely needs more air.

    Also to make sure a carb has plenty of fuel you can set the idle pressure to 7psi or so and give 12 -15 psi when under power.
    I think air is the problem too. I have the idle at 1100 now. Do you think I should Idle it up to 1200 or adjust the air screws?
    It still had 6lbs so I don't think fuel is the problem. Also, my regulator is the one shot deal. It can only be set to a certain psi at a time.

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    Shoot a little carb clean through the air bleeds..it doesn't take much to clog them

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    Checking the air bleeds is a good thing to do.
    Even a small bug can get sucked into them and typically, the air bleeds never get checked.
    If that's the case, you can usually see it with a good light.

    Are you using a mechanical advance in the distributor? If so, they can get sticky and cause a similar problem.

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    Quote Originally Posted by jimsplace View Post
    Checking the air bleeds is a good thing to do.
    Even a small bug can get sucked into them and typically, the air bleeds never get checked.
    If that's the case, you can usually see it with a good light.

    Are you using a mechanical advance in the distributor? If so, they can get sticky and cause a similar problem.
    It's an MSD Pro-Billet without mechanical advance.

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    Can someone show me the location of the air bleed? Is it the four air screws that are on the side of the carb, on each barrel?

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    you could have a piece of junk in the needle and seat. If its hanging the needle open it will run like crapand not idle. Do a test turn your pump on with the spark arrestor off and look down the carb and see if fuel is coming out the boosters. If so pull the needle and seat out. If you just put the pump on then I assume you made new lines, if you used an fittings and hose you could have a piece of the rubber from cutting in the N&S

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    Quote Originally Posted by Sweat View Post
    I think air is the problem too. I have the idle at 1100 now. Do you think I should Idle it up to 1200 or adjust the air screws?
    It still had 6lbs so I don't think fuel is the problem. Also, my regulator is the one shot deal. It can only be set to a certain psi at a time.
    If you are idling that high then you need to check the position of the throttle blades and the transition slot. When viewed from the bottom the slot should look like a square. If the blades are open too far you need to let air in some other way. This basic setup needs done before going any farther.

    Float levels checked also
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    Quote Originally Posted by Sweat View Post
    Can someone show me the location of the air bleed? Is it the four air screws that are on the side of the carb, on each barrel?
    air bleeds
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    Vacuum gauge helped find my similar issue.

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    Quote Originally Posted by Infomaniac View Post
    If it wants to die at idle after being under power it could be several things. More than likely needs more air.

    Also to make sure a carb has plenty of fuel you can set the idle pressure to 7psi or so and give 12 -15 psi when under power.



    How can you do that Ron with a regulator ??
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    Quote Originally Posted by TNYoungblood View Post
    How can you do that Ron with a regulator ??
    You use a bypass regulator with a jet in the valve.. That should always be the regulator to use anyway. BG makes one with a jet in the valve itself. You set the idle pressure with the jet and running pressure with the valve. You can also use an enderle valve to do this.

    There are mechanical valves also that do this. Connected to the throttle linkage.

    The reason pressure is so low on a carb is so the needle and seat are not overpowered and flood at idle. Once it's running and making some power the needle and seat are open and flowing fuel. You can up the pressure while running and flowing fuel
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    Quote Originally Posted by Infomaniac View Post
    You use a bypass regulator with a jet in the valve.. That should always be the regulator to use anyway. BG makes one with a jet in the valve itself. You set the idle pressure with the jet and running pressure with the valve. You can also use an enderle valve to do this.

    There are mechanical valves also that do this. Connected to the throttle linkage.

    The reason pressure is so low on a carb is so the needle and seat are not overpowered and flood at idle. Once it's running and making some power the needle and seat are open and flowing fuel. You can up the pressure while running and flowing fuel


    Thanks for the info Info
    WFLC The REAL #321 Kentucky Drag Boat Association 2016 NJBA 10.0 High Points Champ

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