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Thread: Fuel pump failures

  1. #1
    Member dvfr750f's Avatar
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    Fuel pump failures

    I know this is a much discussed issue, but I wanted to bring it up again as it is a constant headache for many, me included.
    I am looking for insight, solutions, etc...
    History:
    I have an 81 that I have owned for a year now. I have done a good bit o work on the car to included the fuel system. New Fuel distro, steel braided fuel lines, new fuel pump, accumulator, and J Herveys fuel pump kit with his fuel pump. The Car had fuel pump issues before I owned it(records) and it had a J Hervey(JH) pump in it then. It also had the stock fuel pump kit in the tank. The tank is spotless, no contamination.
    The car took a dump on me a few times and quickly figured the pump as the culprit. It would get hot(summer time in ABQ NM) and the pump would get louder and louder. Finally the car would start to buck and sputter till it would just die. So, I ( novice D owner) talked with JH and he said his kit was great so I bought it.
    The car failed shortly thereafter(last summer). New Fuel pump( from JH) and cooler temps brought a a good driving car that is driven a few times a week.
    I recently overhauled the entire cooling system. New, electric, fans for the radiator. water pump, silicon lines, etc..
    Anyway, two weeks ago(high 80s) I was driving with 1/4 tank of gas and the F pump start to scream. I quickly found a gas station topped off and the sound was gone, back to normal. Last week, while driving in city traffic(90deg F, mid day) the car got just above 220deg and then the pump started to sputter again(3/4 tank of gas). I drove it another 7 miles before the car died. I had to let her cool off a few hours and she started right up.

    Questions:
    I am certain the issue is the fuel pump, but why? It is a JH pump and it worked well thru the winter, but AS SOON as it got hot again, she crapped out.
    Both cooling fans are working well. Are they heating up the fuel tank? Does deflecting the air from the tank help? I want to fix this and hope y'all can help!
    LASTLY, of those that have seen or own the new DMC pump/sender unit, what are your thoughts?
    Is there a good fuel pump out there? How/where do you get it?
    Thanks

  2. #2
    Owner since 2007 Farrar's Avatar
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    There are many possible sources of a problem, but I'd start with the easiest to check: electrical. I would backprobe the fuel pump's connector to make sure you have good connectivity. Weak voltage or bad ground would make the pump overheat.
    Last edited by Farrar; 05-30-2013 at 01:37 PM.
    DeLorean status:​ Daily driving my "rolling resto-mod"

  3. #3
    Delorean Guru
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    Try putting a spring into the pick-up hose and make sure when the pump is installed you do not twist and kink the hose. The problem is not the pump. The problem is your pick-up hose is collapsing or kinking and starving the fuel pump. That's why it gets louder and the motor stops. Keeping more than 1/2 tank of fuel helps to prevent this but the fix is to put a spring inside that hose.
    David Teitelbaum

  4. #4
    Junior Member marshdutt's Avatar
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    kinda sounds like vapor lock problems, im only really familiar with vapor lock bc of of my old Volvo 240 (with K-jet) had it when i was younger, so im not an expert on it... but the idea is that as it gets weather gets hotter the fuel is turning to vapor in the fuel lines and messes with the pressure on the way to the engine. Thus starving the engine of fuel. On our Volvo we replaced the intank and inline fuel pump, and it solved problem. The fuel pump should keep the pressure constant forcing into the fuel in there.

    I dont know too much about those fuel pumps from Hervey, but i did hear really good things abut DMC's kit, and came HIGHLY recommended from my mechanic in boulder.

    I know that Tom Quirk Automotive on Girard, near Candelaria, has worked on DeLorean's in the past. and probably could point you in the right direction.
    "Your visions are not limited by what your eyes can see, but by what your minds can imagine. Make your life count and the world will be a better place because you tried" -Ellison S. Onizuka-

  5. #5
    Senior Member Bitsyncmaster's Avatar
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    Did you have John's "power pump"? He claimed that one to never make noise.

    The fuel in the tank does get very hot. I did some testing with a sensor in the tank and I seem to remember when it got above 125 deg F the pump would make noise.

    So far I have not heard any noise complaints from the new DMCH fuel pump/sender unit. I still run a stock pump but I installed a cooler on the fuel return line. If I had not done that, I would try that new DMCH pump.
    Dave M vin 03572
    http://dm-eng.weebly.com/

  6. #6
    Senior Member Silverbullet's Avatar
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    I have to new combo unit... the install is very easy, it is a new modified GM pump, Very quiet, has a self contained fuel pick-up, and I have had no heat issues. Well worth the money to me.

  7. #7
    Administrator Ron's Avatar
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    Quote Originally Posted by Silverbullet View Post
    I have to new combo unit... the install is very easy, it is a new modified GM pump, Very quiet, has a self contained fuel pick-up, and I have had no heat issues. Well worth the money to me.
    ...gotta love the built-in level sending unit.... Way to go if you aren't worried about originality, so to answer your other question, I'd call DMCMW -- they will fix you up, fast, and give great support.

  8. #8
    Senior Member BABIS's Avatar
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    Quote Originally Posted by Bitsyncmaster View Post
    I still run a stock pump but I installed a cooler on the fuel return line.
    where do you have installed the fuel cooler?
    VIN 4502

  9. #9
    Administrator Ron's Avatar
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    Quote Originally Posted by BABIS View Post
    where do you have installed the fuel cooler?
    http://dmctalk.org/showthread.php?15...p-buzzing-cure

  10. #10
    Senior Member BABIS's Avatar
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    My VIN:    4502

    VIN 4502

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