Fuel Starvation question

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    Author Topic: Fuel Starvation question  (Read 1131 times)

    Offline Moparal

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    Fuel Starvation question
    « on: June 07, 2008 - 11:32:51 PM »
    First of all I don't want to run an electric pump on this car

    My car- stock tank, 3/8ths sending unit 5/16 fuel line up to the 6pk. Has a 440 hp carter mechanical stock type pump on the engine now. I plan on running stock 3/8ths line up to pump. Not putting a fuel pressure gauge on either. The stock pump has 3/8ths inlet and 5/16ths out. The factory 6pk lines are 5/16ths.

    I was driving my car up to the track today to go watch some racing. Good way to spend 7 bucks.  Well, I decided to help break the engine in a bit more and ran 3rd gear up to 6200. I have a 410 gear and a 4 spd.

    I think I sucked the fuel right out of the line. After 3rd, I shifted to 4th and just eased the speed back down to around 70 or 75 I guess. Tach said 4500 and I got 275x60x15 ta radials on the back. Then I notice that the car wasn't getting any fuel when I hit the pedal a bit in 4th. I had to coast for about 300 ft to let everything catch up.

    Now I know I can have more volume when i replace the fuel line to 38ths, but do you think I need a bigger mechanical pump?  When I mash my gas pedal and I am beside someone, I dont wanna have to use any excuses if I get beat in a street battle. I wanna make sure I put out all it has to give.

    Think the bigger line is all that's required? Or maybe a carter mech pump that puts out 6.5 psi?  My car is not a race car, but I don't want this issue to happen again.
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    Offline hemiken

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    Re: Fuel Starvation question
    « Reply #1 on: June 08, 2008 - 01:10:15 AM »
    Hi Alan,

    Sounds as if you already know what reply you will get.    You will have to up grade the 5/16 line to 3/8 like you said and change out for a Carter mechanical and a 3/8 line from the pump up to the carbs.  Not a race car but still a lot of carburation to feed that big 440, it is no 318 anymore buddy :lol:
    Would be good if you could hook a temperary fuel pressure gauge in the cabin area to watch what the fuel does under full throttle old mate. :2thumbs:
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    1970 Barracuda   (O^--^===|===^--^O)
    1971 Barracuda   (O O {]{]{]|[}[}[} O O)
    1970 Challenger  (O O [======R/T=] O O)
    1971 Challenger  (O O ===== ===== O O)
    I pay homage to the best Mopars ever built.

    Offline wally426ci

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    Re: Fuel Starvation question
    « Reply #2 on: June 08, 2008 - 08:02:44 AM »
    I think I'm gonna need one also.....
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    Offline Changin Gears

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    Re: Fuel Starvation question
    « Reply #3 on: June 08, 2008 - 08:25:43 AM »
    You might not need that 3/8 line, I know of more than 1 440-6 running fine with a 5/16 (one ‘cuda runs 7.6’s in the 1/8th with 4.10’s without a problem, another is the Polara below).

    Couple of things I have found are the headers cook the fuel line running between the frame and the engine.  This is on the vacuum side of the fuel system.  Fuel boils at a lower temp at a lower pressure (vacuum), combined with this hot weather and this spells vapor lock.  Sounds like what you are experiencing.  This is one reason electric fuel pumps work so well, this section of the fuel system is under pressure.

    Another thing is that the restriction of a 5/16 fuel system is not the lines, but the fittings.  If you look at the opening in them they are about half the size of the fuel line.  I always “port” mine by drilling them out.
    « Last Edit: June 08, 2008 - 08:31:03 AM by Changin Gears »
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    The goal never changes - Stop the 60' timer with your back tires

    Offline Moparal

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    Re: Fuel Starvation question
    « Reply #4 on: June 08, 2008 - 08:26:15 AM »
    Kenny, the line up to the carbs is factory 6pk lines. The only line I didnt change was the one to the pump from the tank. Even the pump is factory 6pk. I was wondering if I should step up to an aftermarket performance carter pump. If I shift out at 5500 in every gear it hadnt done that. So I was thinking volume and not pressure. I didn't get to notice this problem untill Drew and I installed the new clutch and I swapped over to the 410 gear set. There is one thing I do know from experience. And that is do one thing at a time. So I will go to inlinetube.com and see about buying the factory pre bent 3/8ths line first. I kinda agree with you on a temporary fuel pressure guage, but really dont want to add the extras to the car. If I start doing that, I know myself and I will start makeing the car go faster and faster and faster. This car I just want as stock. Maybe I shouldn't of added the bigger cam and oversized valves.



    I will just put the car in a container and ship it to you so you can work out the bugs for me. :bigsmile:
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    Offline Moparal

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    Re: Fuel Starvation question
    « Reply #5 on: June 08, 2008 - 08:34:25 AM »
    I understand what you are saying C.G.  I was thinking about vapor lock at first.  It was 94 degrees yesterday. I don't have headers, the line is run along the frame as factory, I had just got the car out of the garage which was in air conditioning, and had only drove for 2 miles when I tried. My ecs system is new, so the venting lines are all working good. It is possible I have a week pump too.

    Did you go to the Decatur cruise last night?  I opted out to go to the drags.
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    Offline Changin Gears

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    Re: Fuel Starvation question
    « Reply #6 on: June 08, 2008 - 08:39:52 AM »
    I went over there, it was a mild turn out. 

    By the way I fixed my vapor lock problem by insulating the fuel line in this area.  You could also try driving without the gas cap (you won't be very green) to see if all your lines are working correctly. 

    Another thing that it could be is your fuel pump push rod being worn out, had this happen to me last year.
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    The goal never changes - Stop the 60' timer with your back tires

    Offline hemiken

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    Re: Fuel Starvation question
    « Reply #7 on: June 08, 2008 - 10:15:06 AM »
    Quote from: Moparal on June 08, 2008 - 08:26:15 AM
    Kenny, the line up to the carbs is factory 6pk lines. The only line I didnt change was the one to the pump from the tank. Even the pump is factory 6pk. I was wondering if I should step up to an aftermarket performance carter pump. If I shift out at 5500 in every gear it hadnt done that. So I was thinking volume and not pressure. I didn't get to notice this problem untill Drew and I installed the new clutch and I swapped over to the 410 gear set. There is one thing I do know from experience. And that is do one thing at a time. So I will go to inlinetube.com and see about buying the factory pre bent 3/8ths line first. I kinda agree with you on a temporary fuel pressure guage, but really dont want to add the extras to the car. If I start doing that, I know myself and I will start makeing the car go faster and faster and faster. This car I just want as stock. Maybe I shouldn't of added the bigger cam and oversized valves.



    I will just put the car in a container and ship it to you so you can work out the bugs for me. :bigsmile:
    Hey Alan,
    That is a bit extreme buddy :smilielol: would be a he11 of a lot cheaper if i fly over and help with the set up old mate :roflsmiley: you do kill me sometimes. :2thumbs:

    Good idea to tackle one thing at a time, CG has a valid point about the fuel getting hot aswell.  Insulation can be acheived very quickly to check this as a problem. :swaying:
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    1970 Barracuda   (O^--^===|===^--^O)
    1971 Barracuda   (O O {]{]{]|[}[}[} O O)
    1970 Challenger  (O O [======R/T=] O O)
    1971 Challenger  (O O ===== ===== O O)
    I pay homage to the best Mopars ever built.

    Offline Moparal

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    Re: Fuel Starvation question
    « Reply #8 on: June 08, 2008 - 04:36:59 PM »
    I already have my wife looking into expedia for summer tickets to your place. Just to visit. But I must say, I saw an Aussie movie called WOLF CREEK, and it had me a bit on the stay in the public phase.  True story of a serial killer you got over there and hasn't been found :scared:
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    Offline wally426ci

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    Re: Fuel Starvation question
    « Reply #9 on: June 08, 2008 - 04:45:05 PM »
    I saw that too..... creepy....... It sounds pretty lawless out in the Outback Kenny....  :misbehaving:
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    Offline Moparal

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    Re: Fuel Starvation question
    « Reply #10 on: June 08, 2008 - 05:58:28 PM »
    I just went to inline tubes web site. I will order this in the morning. They are in Michigan. Very good prices too

    3/8ths factory fuel line oem bends  #PEF7002   69 bucks
    Clip set  DEF304                                          23.50
    FHS 301                                                       4.50

    This is the start to my question, and I really should do this anyways.  I think it is a very good price to
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    Offline hemiken

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    Re: Fuel Starvation question
    « Reply #11 on: June 08, 2008 - 07:38:44 PM »
    Quote from: Moparal on June 08, 2008 - 04:36:59 PM
    I already have my wife looking into expedia for summer tickets to your place. Just to visit. But I must say, I saw an Aussie movie called WOLF CREEK, and it had me a bit on the stay in the public phase.  True story of a serial killer you got over there and hasn't been found :scared:
    Quote from: wally426ci on June 08, 2008 - 04:45:05 PM
    I saw that too..... creepy....... It sounds pretty lawless out in the Outback Kenny....  :misbehaving:
    :smilielol: :scared: That's in the outback guys............. :o We do not talk about that around here :misbehaving:






    Just kidding, that movie is full on :22yikes: but that is like the same distance as California is from both you guys to me here in Brisbane. :roflsmiley:
    Remember Alan, You are most welcome to stay at my place when you are here.   :woohoo:
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    1970 Barracuda   (O^--^===|===^--^O)
    1971 Barracuda   (O O {]{]{]|[}[}[} O O)
    1970 Challenger  (O O [======R/T=] O O)
    1971 Challenger  (O O ===== ===== O O)
    I pay homage to the best Mopars ever built.
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