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  1. captain mike

    Air in fuel, vacuum side is NOT leaking. Advice?

    Update: I plugged the return line from from the engine to the tank, I was able to maintain much better pump pressure at the hand primer. I found a damaged return line o-ring, replaced it. Could have been weeping, but it certainly did not appear to have been leaking, replaced it anyway. I put a...
  2. captain mike

    Air in fuel, vacuum side is NOT leaking. Advice?

    Ok, I'm familiar with that part. I thought that might be the regulator, thank you for the info. I'm headed home soon to check a few more things, this included
  3. captain mike

    Air in fuel, vacuum side is NOT leaking. Advice?

    That is a solid idea, thank you. I need an outside opinion, as I've just been bashing my head on a wall... I agree that with the ends blocked off I can vac or pressurize the system... the thought of doing it on the feed/return lines at the engine hadn't yet occurred to me I guess... seems pretty...
  4. captain mike

    Air in fuel, vacuum side is NOT leaking. Advice?

    The rail pressure regulator seems to be fine, there is no fuel coming from the fitting when cranking. I'm not sure about return pressure regulator, where is it located?
  5. captain mike

    Air in fuel, vacuum side is NOT leaking. Advice?

    Apologies if my quote is misleading. You are correct that after hooking the line back to the cp4 inlet hose, I start to lose pressure from the hand primer. I've read that with a properly operating system, I should be able to pump the primer til firm, and it should hold and remain firm even...
  6. captain mike

    Air in fuel, vacuum side is NOT leaking. Advice?

    But, no. I did not block the return when hand priming the system with the cp4 hooked up
  7. captain mike

    Air in fuel, vacuum side is NOT leaking. Advice?

    I have not vacuum tested it with the cp4 hooked up, only hand prime with the cp4 connected. I can't connect my vac pump to anywhere on the outlet side of the cp4
  8. captain mike

    Air in fuel, vacuum side is NOT leaking. Advice?

    Thank you. I certainly try to exhaust every option before turning to the ol interwebs for answers. I'm fairly certain my problem is not in my filter assembly, nor any of the points from the tank to the filter... I've isolated each section and vacuum tested each, as well as the entire run from...
  9. captain mike

    Air in fuel, vacuum side is NOT leaking. Advice?

    Again this issue was non existent prior to doing a head gasket change. Also worth noting that there is no visible fuel leaking from the positive pressure side from the filter
  10. captain mike

    Air in fuel, vacuum side is NOT leaking. Advice?

    I did vacuum test it. Blocked off the input and applied 10inHG vacuum to the output (using the rubber hoses off the truck to also rule them out as air intrusionpoints), with filter on. Left sit for an hour, no loss of vacuum. After reinstalling the filter housing to the truck and connecting the...
  11. captain mike

    Air in fuel, vacuum side is NOT leaking. Advice?

    Here goes... 2016 lml duramax, silverado 2500hd automatic 4x4 ltz. 240k miles My truck had zero fuel issues. After replacing my head gaskets, I can't keep it primed. Will lose prime in minutes. Truck runs fine after started. I started diagnosing the typical places. Replaced fuel filter, and...
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