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    Volvo Penta 7.4 problems after a new gas tank..

    Let me clarify.. I think its the case that larger lines where all connections are smaller generally does not add anything as the restriction is the smallest point.. But I agree if we could go all 1/2 on all fittings that would assist in more flow.. As for the anti syphon, that is a great...
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    Volvo Penta 7.4 problems after a new gas tank..

    Yeah good catch, I do need to put it up high.. I am worried its going to not flow enough but we will see when I test it. So I hear you.. but interestingly we tested all that.. So first, it is my belief that while we have an older 454 block its mildly built (probably 9:1) so I would assume...
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    Volvo Penta 7.4 problems after a new gas tank..

    Good catch, not yet, I am waiting for a new one to arrive that is AN6 inline. I know they are required, but based on my reasearch they can be a nightmare with this exact situation. So we decided to go inline and down low just before the pump so that hopefuly it does not create another cavitation...
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    Volvo Penta 7.4 problems after a new gas tank..

    Well we solved it.. So for everyone in the future. Basically we had to install the fuel pump lower in the bilge.. Let me explain.. So for all these pumps they are considered PUSHERS not PULLERS.. so they have limited lift capacity, most only rated at 12".. Now on our boat it turns out the bottom...
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    Volvo Penta 7.4 problems after a new gas tank..

    I like the vacuum guage suggestion.. It might be tricky to get a second line into the tank and attach to the inlet of the pickup tube.. so it may have to be at the top of the pickup tube which then I think changes that from vacuum to pressure.. I had planned on testing with a fuel can this...
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    Volvo Penta 7.4 problems after a new gas tank..

    Hey Thanks guys! So the pickup is at top.. Think of a 170gal square with a 2" recessed square area at the back that has 5 bungs. 2 inlets from our saddles an Outlet for the pickup tube, level sensor hole and 1 additional bung we capped off for the future in the event we want to go injected and...
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    Volvo Penta 7.4 problems after a new gas tank..

    Yep as I noted in my original post we have checked for tank vacuum, cap on, cap off.. Verified vent tubes are free flowing, etc.. no change so I do not think its related to that.. I am really leaning to fuel cavitation at the pickup, and I have clear fuel line coming in so if I see bubbles...
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    Volvo Penta 7.4 problems after a new gas tank..

    Yeah that pump is 110gph however it is considered a pusher not a puller so the lift capacity is actually only rated for 12" accoding to Holly.. So this could be the issue.. While we are not required to run a regulator, on the many other chevy (car motors) I have built running a regulator on...
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    Volvo Penta 7.4 problems after a new gas tank..

    Hey thanks! I am happy I found the forum and hope to contribute more! As for your questions.. Yes 2x AN8 Vent Tubes that vent to each side of the outer hull. Both located at the front upper corners (so they do not flood under accel) No anti syphon at the moment as this was bypassed to remove...
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    Volvo Penta 7.4 problems after a new gas tank..

    Ok all looking for some advice here.. I am fairly experienced engine guy so not a newb by any means.. but this one is stumping me. The boat is running like $##@ Stalls out, misses and in many cases cant get any power We recently did a major update and put in a new tank as the old main tank had...
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