Drivability Issue with '86 J70

steveb Dec 24, 2014

  1. steveb

    steveb New Member I am in portugal

    Hello! I just joined these forums. I got a technical question, and I hope this is the right place to ask.

    Recently, been having a problem with drivability of my J70 diesel . I'll try and do my best to explain:

    Whenever I take an incline, something greater than 20 degrees, I lose almost all acceleration, especially in the low RPMs, and the more gas I give it, doesn't help. Actually, I need to let off the gas quite a bit, and just crawl up the incline until the J70 levels out...then acceleration returns. Sometimes, I have to take an incline in 1st gear and super slow, as second or third gear do not keep the speed, the J70 decelerates, and then I'm left with only 1st gear and a max speed/acceleration until the degree of incline changes. In addition, there is a noticeable bucking of the J70, as if its about to explode with acceleration/power, but never does. When I return to a more or less horizontal or decline driving, the J70 regains all its power (for what it is).

    I've checked the fuel line and filters, and replaced the filter as well, and that seems good. I have yet to do any checking on the intake from the gas tank, cause that is just a bigger job and I use the J70 regularly.

    I've also thought about this being a fuel injector issue, because on an mid-eighies VW Vanagon, I once had similar bucking issues, which required me to remove and clean the fuel injectors (and it worked to fix that problem).

    So before I choose to investigate the front or the back end of the Fuel System, I just wanted to throw this out to the community here, and see if anyone has a recommendation for me.

  2. JonFJ1969

    JonFJ1969 Active Member

    HI, it may be the same issue i had, turned out to be the filter inside the tank, i have just changed this today and all power has returned although mine was nothing to do with position of car. based on the issue i had it might be worth putting an air line on the inlet of the filter in the engine and blowing back any crap that has managed to fill the internal tank filter, either way long term i think you need to change the internal filter though, cheers Jon
  3. Yorkshire Devil

    Yorkshire Devil Well-Known Member

    As Jon said those intake pipes clog up at the end but they also rot on the outside on the top of your tank sometimes very hard to spot.

    Sent from my iPhone using Tapatalk
  4. steveb

    steveb New Member I am in portugal

    Thanks for the replies everyone. I think I'll be taking a look at that gas tank intake very soon.

    I guess that a clogged intake could be hard-pressed to function when the car takes an incline, because the clog is sits at the point in which the gas in the tank moves? Still seems weird, but...a solution must be found!
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