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  • With today's electronic lift pumps from FASS and Airdog, TYPICALLY they do not come with a way to easily adjust fuel pressure. There are options out there but they are quite spendy and there's easier ways to accomplish the same thing.


    So for those who have pumps that do not have an external/adjustable regulator, your pump more than likely uses a spring and ball to regulate fuel pressure. Springs should be provided from the pump manufacturer to provide adequate pressures. Typically between 16-18psi. The pumps use a hard plastic ball, either a Buna or Viton ball. This will create a seal when the pump is off and keep fuel from "leaking" or "moving" in the lines once the pump is off.


    The springs can be inconsistent which can cause erratic fuel pressure readings or lower then expected readings.




    Using this diagram of a FASS system, if you remove the hose/fitting that is connected to the "air/vapor return to the tank" you will find a spring a ball, it will look like this.




    If your spring comes out looking like this...




    You were more then likely experiencing erratic fuel pressures. You could either straighten out the spring and reinstall or replace the spring all together. I only have experience with FASS but I called FASS support and they sent me a replacement. I imagine the same would happen with Airdog.


    The next factor in all this are the balls. In my research I've found that FASS uses a Buna ball and Airdog uses a Viton ball. I was having a mixed bag of issues, erratic fuel pressures and also lower then expected fuel pressures. Upon removing the spring and ball I found my spring had twisted (previous pic) and that the ball had indented into the spring.




    You can see the indentation here. I tried a couple replacement balls from FASS with the same results. I then went with a Viton ball and the problems haven't returned. The Viton ball is stronger material and seems to be holding up well.


    If you're still having lower pressure issues then you can put a washer in to shim the spring and raise pressure. The following measurements should get you in the ball park but make sure you double check you're not adding any additional restriction by using to small of an ID. Here are the measurements:


    OD - .631"

    ID - .320"

    thickness - .039"


    ***This washer/shim should be added between the fitting and the spring NOT between the spring and ball.***


    So what helped fixed my issues was going with a Viton ball and a 17lb spring. This isn't meant to say one company is better then the other, just what I found out in my research and what fixed my problem. The point of this article is to help educate others on potential fixes.


    ***Additional notes***


    List of parts I used


    Viton Ball HERE

    17lb spring HERE


    I understand these are labeled as Airdog parts but they worked fine in my FASS 150.


    The Airdog fitting DID NOT work on my FASS pump so if you're looking to replace that on your FASS 150 you would need to contact FASS to get a replacement. Here's the difference






    Pretty noticeable difference in threads and overall length so if replacing these fittings they must be brand specific.







    User Feedback



    I tried this made pressure go from 14 psi to 30psi ?Before  it was eradic 20mph 30mph worked good at 50 go crazy around 60 mpg

    any thing over 60 was ok.

    Link to review
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