fuel pump problem
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fuel pump problem

  1. #1
    WHERE I AM IDAHO 392 cruiser's Avatar
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    Default fuel pump problem

    ok i know this has been asked before but here i go, again...i have a 392 hemi in my 70 raysoncraft i changed from hilborn stack injectors to 2x 750 edlebrock carbs just for simplicity reasons, 1/15 gears 11x15 prop 450 hp no biggie so far except i run out of gas after 10 seconds at full throttle i let it idle down it fills back up off i go as long as i dont go full trottle ...i have a carter rotary pump 75 gph mallorey fuel water seperator #6 feed lines ,do you think the pump is to small ??? maybe a holley blue label 120gph???to keep up
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  3. #2
    Senior Member flat screwd's Avatar
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    I have run T.R. intakes with duel carbs of a holley red with no problems. Whats your fuel pressure at idle and W.F.O. I would check that first befor changing any parts.

  4. #3
    Or Seth, either one Budweiser's Avatar
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    had a similar issue and I ran an Edelbrock carb. Very different set-up and circumstances, but same problem. Turned out it was in fact the fuel pump.

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  6. #4
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    Try a boost referenced regulator like a Mallory.

  7. #5
    WHERE I AM IDAHO 392 cruiser's Avatar
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    i bought a aeromotive 1000 pump off ebay guess, ill give it a try in the spring

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    Senior Member EVILFORCE's Avatar
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    Dumb question. Did you check you float levels? If they are ok then you need a gauge in like to see where pressure is at.
    No Fool Like A Old Fool is there?

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    Senior Member cave's Avatar
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    Quote Originally Posted by 392 cruiser View Post
    i bought a aeromotive 1000 pump off ebay guess, ill give it a try in the spring
    Your set on the pump now. Just make sure you run a relay to the pump.
    30 direct to battery positive
    85 from keys hot wire (on position HOT) This is simply the hot wire.
    86 to ground
    87 to positive side of Fuel pump.
    I use a Bosch 5 tab type Relay from Autzone or NAPA. The 4 tabs are more costly and the 5 tab does the same thing for less.

    I would also check the floats. Even with the A1000 pump, if your floats are closing too soon your gunna have issues.
    Takin it home

  10. #8
    WHERE I AM IDAHO 392 cruiser's Avatar
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    i bought the pump because
    1 i changed to a bigger maroso style fuel water seperator instead of the fram bowl style
    2 i could plug off the fuel almost with my finger so i know there was no pressure
    3 carbs worked perfect with the old manuel style pump
    4 so has to be the fuel pump filter combo i guess i will use your advise and use a relay

  11. #9
    Senior Member SoldHondaBoughtHondo's Avatar
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    Quote Originally Posted by 392 cruiser View Post
    ok i know this has been asked before but here i go, again...i have a 392 hemi in my 70 raysoncraft i changed from hilborn stack injectors to 2x 750 edlebrock carbs just for simplicity reasons, 1/15 gears 11x15 prop 450 hp no biggie so far except i run out of gas after 10 seconds at full throttle i let it idle down it fills back up off i go as long as i dont go full trottle ...i have a carter rotary pump 75 gph mallorey fuel water seperator #6 feed lines ,do you think the pump is to small ??? maybe a holley blue label 120gph???to keep up
    Same problem as mine...think simple...75 gph....half a gallon in half a minute. Pull the feed lines of both the carbs, stick them in a gas can, turn the pump on. In 30 seconds you should have at least half a gallon...and i am guessing you wont..if the float levels were that far off you probably would have made full throttle in the first place abd if you did, the motor would shut clean off. If there is no restriction in the separator and the fue will flow easily from the tank, check the voltage to the pump when it's running..if it's 12 volts, it's a pump problem...I have a holley black 125 gph....it was doing the exact same thing...pump had 12 volts, didn't get hot when running...took it over a minute and a half to pump a gal. It should have done 2 gal. a min. took it apart..the motor sounded fine..the gears looked ok...found the inlet screen sorta plugged..cleaned it and put it back together..it pumped half a gal. in 30 seconds. the pump has an internal regulator..spring and check ball..set at 5lbs..i can pinch it off with my fingers...ran the boat today..problem solved...

    And as a note...the inlet screen is the filter for the pump...fuel filters and separators belong between the pump and the carbs with an electric pump...a manual pump will pull fuel better that it pushes...that's why it's on the motor..and electric pump pushes better than it pulls. It needs to be mounted close to the tank if possible and even minor restrictions on the inlet side will degrade it's performance.

  12. #10
    Senior Member Schiada 201's Avatar
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    Also If you don't run a return fuel system I suggest that you should. Keeps the fuel system at a constant flow instead of the pump stopping and restarting, the fuel pressure is exactly where the carb demands also cooling the fuel down as the pressure will cause the fuel to be hot.
    There are times the carb will need ex. 10 lbs and your fuel dead end system can't supply if with a return system it will supply the needs . The return systems makes it easier to diagnose

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