Page 5 of 5 FirstFirst ... 3 4 5
Results 41 to 46 of 46

Thread: Fuel pump failures

  1. #41
    Delorean Guru
    Join Date:  May 2011

    Location:  Northern NJ

    Posts:    6,970

    My VIN:    10757

    Club(s):   (DMA)

    Even if you use a different pump, pumping hot fuel is going to be hard on it as opposed to cool fuel. Hot fuel is easier to cause cavitation in and that leads to the noise and higher wear in the pump. The fuel lubricates and cools the fuel pump. If it pulls in air or cavitates it increases the wear on any pump. Keeping the fuel cooler is the objective, not trying to get a "better" fuel pump. Some pumps may be more forgiving of cavitation and wear but it still is not a good situation. Insulation can help reduce heat transfer from the water pipes underneath. The air dam can reduce the hot air from the radiator and finally you can wrap a coil of pipe around the A/C accumulator to remove heat from the returning fuel. Once the pump gets noisy it is only a short time till failure. It also seems to get noisy when you don't have a full tank. I think there are 2 reasons for that. One, more fuel will take more heat to get hot (more mass) and 2, the pump is submerged so the noise is muffled, the pump is cooled, and the fuel is less likely to cavitate with a little bit more pressure from the fuel above the filter. Depending on your local climate, you may have to take more steps to minimize the problem of hot fuel. On most fuel injection systems the pump in the tank doesn't work very hard. All it is supposed to do is move the fuel out of the tank to another pump which puts the fuel under high pressure. In the Bosch K-Jet system the tank pump does it all and to a very high pressure because the fuel injectors are mechanical, not electric.
    David Teitelbaum

  2. #42
    Member jorge figueroa's Avatar
    Join Date:  Jun 2011

    Location:  Puerto Rico

    Posts:    60

    My VIN:    01279

    fuel pump failures

    Quote Originally Posted by David T View Post
    Even if you use a different pump, pumping hot fuel is going to be hard on it as opposed to cool fuel. Hot fuel is easier to cause cavitation in and that leads to the noise and higher wear in the pump. The fuel lubricates and cools the fuel pump. If it pulls in air or cavitates it increases the wear on any pump. Keeping the fuel cooler is the objective, not trying to get a "better" fuel pump. Some pumps may be more forgiving of cavitation and wear but it still is not a good situation. Insulation can help reduce heat transfer from the water pipes underneath. The air dam can reduce the hot air from the radiator and finally you can wrap a coil of pipe around the A/C accumulator to remove heat from the returning fuel. Once the pump gets noisy it is only a short time till failure. It also seems to get noisy when you don't have a full tank. I think there are 2 reasons for that. One, more fuel will take more heat to get hot (more mass) and 2, the pump is submerged so the noise is muffled, the pump is cooled, and the fuel is less likely to cavitate with a little bit more pressure from the fuel above the filter. Depending on your local climate, you may have to take more steps to minimize the problem of hot fuel. On most fuel injection systems the pump in the tank doesn't work very hard. All it is supposed to do is move the fuel out of the tank to another pump which puts the fuel under high pressure. In the Bosch K-Jet system the tank pump does it all and to a very high pressure because the fuel injectors are mechanical, not electric.
    gentleman 90% of the heat comes from the cooling tubes that pass under the gas tank.
    the other 10% comes from the radiator through the electric fans that heat the front top of the tank and the fuel pump.
    With this simple thermal protection drastically reduces the heat that is transferred to the tank and gasoline.

    It is very easy to test just have to measure with a thermometer
    so they can see the different temperatures of the tank with thermal protection and without it.

    51364628_2194182390637772_8732333231971500032_n.jpg50980890_2194182357304442_3267538366345773056_n.jpg50713257_2178710612184950_943280160864468992_n.jpg50440744_2178710542184957_6044630208093356032_n.jpg

  3. #43
    Senior Member Bitsyncmaster's Avatar
    Join Date:  May 2011

    Location:  Leonardtown, MD

    Posts:    7,229

    My VIN:    03572

    Quote Originally Posted by jorge figueroa View Post
    gentleman 90% of the heat comes from the cooling tubes that pass under the gas tank.
    the other 10% comes from the radiator through the electric fans that heat the front top of the tank and the fuel pump.
    With this simple thermal protection drastically reduces the heat that is transferred to the tank and gasoline.

    It is very easy to test just have to measure with a thermometer
    so they can see the different temperatures of the tank with thermal protection and without it.
    I used two thermocouples. One on the line leaving the tank and one on the line returning. With a hot engine the return line was about 1.0 degree F higher. Now depending on how much return flow you get, that would add a lot of the heating.
    Dave M vin 03572
    http://dm-eng.weebly.com/

  4. #44
    Member dvfr750f's Avatar
    Join Date:  Oct 2011

    Location:  Key West

    Posts:    42

    My VIN:    01067

    Update

    Hi ya'll. I am glad to se this thread is still active. I just wanted to update. After I made the mod way back when, I experienced no more frequent failures. I took the car to Va and drove it there. No issues. In 2016, I drove the car from Va to NM. It performed well. After leaving Amarillo and driving to ABQ NM I experienced a fuel pump failure, but I think that was b/c the tank was more than half empty for awhile. I had a spare and changed it roadside. She has been in storage these past few years but yearly, she starts right up. I keep the battery on a tender(outside the car).
    Has anyone updated to the NEWish DMC fuel pump system? I think that is my next course of action. I will be taking the Car to SC soon.
    Cheers

  5. #45
    Senior Member hippieman9's Avatar
    Join Date:  Jan 2018

    Location:  Haw River, NC

    Posts:    241

    My VIN:    06668 81' Grey interior, 5 speed, Grooved hood. Previous owner of 16301, in 2001.

    Quote Originally Posted by dvfr750f View Post
    Hi ya'll. I am glad to se this thread is still active. I just wanted to update. After I made the mod way back when, I experienced no more frequent failures. I took the car to Va and drove it there. No issues. In 2016, I drove the car from Va to NM. It performed well. After leaving Amarillo and driving to ABQ NM I experienced a fuel pump failure, but I think that was b/c the tank was more than half empty for awhile. I had a spare and changed it roadside. She has been in storage these past few years but yearly, she starts right up. I keep the battery on a tender(outside the car).
    Has anyone updated to the NEWish DMC fuel pump system? I think that is my next course of action. I will be taking the Car to SC soon.
    Cheers
    I have the DMCH fuel pump/sender combo and love it. No issues, only suggestion is ditch the rubber lines that come with the kit and install nylon. And get a 90į return line fitting for the pump, donít know why it comes with a straight one... had mine for 10 months and 5,000 or so miles, no issues. Fuel gauge is much more accurate as well.

  6. #46
    Delorean Guru
    Join Date:  May 2011

    Location:  Northern NJ

    Posts:    6,970

    My VIN:    10757

    Club(s):   (DMA)

    For a while a lot of owners had problems with the unit holding rest pressure and in some cases they replaced or added a check valve. Some experienced problems with the sender for the gauge, inaccurate, intermittent or failed. It appears that DMCH went through versions or vendors and it must be better now since there seem to be fewer complaints about the units they are shipping now. It is a nice part but it is expensive. A lot simpler to install!
    David Teitelbaum

Page 5 of 5 FirstFirst ... 3 4 5

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •