Need help with 5.3 ls swap

Discussion in 'Engine Swaps (Gas) LS, Vortec, LT1 , etc.' started by 86K1o, Oct 5, 2016.

  1. 86K1o

    86K1o Junior Member

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    So I've decided to do the 5.3 swap and need guidance on the fuel system and harness. Right now I have dual saddle tanks and I was wondering if the fuel pumps will fit in my 1986 fuel tanks or do I need to by an 87+ fuel tank. Also what fittings do I need or filter/regulator would I need for the ls swap. And for the harness how hard is it to modify to standalone by yourself.
     
  2. 1987 GMC Jimmy

    1987 GMC Jimmy Full Access Member

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    I'm a ding dong on LS stuff, but I know that folks typically go for the 87+ tanks because of the electric in tank pump that TBI requires versus the block mounted pump of the earlier years. If you could score the metal lines from the same year truck, there's your filter setup right there since they all used the frame rail filter there for a while. Plus, they're more appropriate for the higher fuel pressure you'll be running. I'm afraid I don't have a clue on the other, and I hope what I said here is helpful. Maybe someone will chime in and give you better advice; I just wanted you to have some feedback on your first post. And welcome! I've been to Farmington before. Quite a different landscape than the Deep South.
     
    Last edited: Oct 6, 2016
  3. yevgenievich

    yevgenievich Full Access Member

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    Either keep existing tanks and run external fuel pump or generally more reliable 87+ tanks/intank pump set up. You would likely need a tank switch valve from fuel injected truck as well. Walbro 255 intank pumps can be mounted instead of factory tbi pump. Also would need to rework the lines under the hood and add inline filter somewhere along the line. Some ls fuel rails have pressure regulator and return line, some do not and can use c5 corvette filter(filter with pressure regulator built in). Harness can be stand alone or rebuild factory ls harness.
     
  4. dougbert

    dougbert Full Access Member

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    I documented my 87 tank swap in my 84 GMC K1500 build in my signature below.

    I built my own AN based fuel lines - didn't think about finding the fuel lines for 87 OEM like mentioned above. Had to toss my dual tank switch - it cannot handle the pressure

    pre-87 mechanical fuel draw from engine fuel pump from the tank - only works for older pattern
    87--?? TBI 15 lbs pressure from pump in tank to engine
    LS 58 lbs pressure from pump in tank to engine

    the old tank switch burst on a buddy's build when he tried to reuse it with a LS engine


    as for the harness, I read all the DOCs from www.lt1swap.com and followed his instructions to modify my own harness - learned a lot
     
    Last edited: Oct 6, 2016
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  5. 86K1o

    86K1o Junior Member

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    Thanks for the replies everyone, plenty of information. So I should get an 87-91 tank with sending unit then run the walboro 255 pump instead of the OEM pump? Also I have a return style fuel rails, if Im not mistaken as stated by yevgenievich I dont have to run the vette filter/regulator? I can just run a fuel injection filter? Ill check out your build dougbert. And I think for the time being I'm just gonna run one tank and eliminate the dual tank switch.
     
  6. 86K1o

    86K1o Junior Member

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    after looking at dougbert's build thread, I'm thinking of getting an 87' 16 gallon tank, ACDelco MU1614 GM fuel pump(will this fit my 87 tank) also all the fittings mentioned in his fuel design,
     
  7. foamypirate

    foamypirate Full Access Member

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    MU1614 won't work with the 87' tank, as it's a full fuel sender assembly. The ACDelco EP381 is a pump that would work great for you. Just avoid Ebay and Amazon, they are full of knock offs. I'd get it from RockAuto.
     
  8. 86K1o

    86K1o Junior Member

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    Thanks, I've also heard of some people running an ls swap with fuel tanks without baffels? would this be okay as long as fuel doesnt run low? Im thinking of buying an 87 r10 fuel tank with sending unit, then running a walboro 255 gss 342 fuel pump. Would this application work?

    Thanks
     
  9. foamypirate

    foamypirate Full Access Member

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    Definitely run a tank with baffles. There's always going to be that one time you run it low, and it becomes a safety issue. Pull out into traffic in a hurry, and you're low? Truck could stall, leaving you stranded in the road way, just as one example. For $80, you can get the new 87' tank with baffles, so it sounds like you are on the right track with that.

    I believe the GSS 342 is the correct pump, but again, be wary of knockoffs, they are everywhere. I bought the Walbro 255s for my swap from fuel-pumps.net. They come with an install kit with the wiring adapter, pump sleeve, filter sock, etc. Most other places, only sell the bare pump. The PN for the kit from fuel-pumps.net is the 5CA400HP. My pumps drop shipped directly from a Walbro distributor, so you can be certain they are geniune.
     
    Last edited: Oct 19, 2016
  10. Qwk

    Qwk Full Access Member

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    That will work.

    I have an 87 and used the stock sending unit with a Racetronix 340 pump.

    [​IMG]

    Stock one.
    [​IMG]

    The 87 tank has a "box" around the pump, so the pump wont starve for fuel. Also, Rockauto was the cheapest I could find on the sending unit, tank and straps.

    Good luck with it!:cheers:
     
  11. 86K1o

    86K1o Junior Member

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    Thanks guys, helped a lot. This is my first ls swap and It is all new to me. Also what fittings would I need? I have a return style fuel rail so I'm guessing I wont need the vette filter/regulator? What fittings would I need at fuel rails? and on sending unit? also would I still need a fuel filter? if so whats recommended?
     
  12. foamypirate

    foamypirate Full Access Member

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    Most people end up building the fuel system with AN fittings. If you go that route, you'll need a 3/8th Quick Disconnect to -6AN, and a 5/16 Quick Disconnect to -6AN (3/8 is the feed, 5/16 is the return) for the rail.


    3/8 to -6AN QD is Russell 644123
    5/16 to -6AN QD is Russell 640863

    From there, you'll want a short length of hose for each, to allow for engine movement, and then a hard line for each on the frame back to the tank. I used pre-made Fragola PTFE lined -6AN hose. 36" should be enough length to easily reach the frame (I made a 30" work, but not as optimal as the 36" would have).

    You should be able to re-use the existing hard lines you already have (assuming you have both feed and return, otherwise you'd need to add the return line), you'd just need to adapt them to AN. You can either by an AN flaring tool, or they sell AN compression fitting adapters.

    Russell's compression fittings are ridiculously expensive, Earl's are much more affordable. Here are the PNs:

    3/8 - AT165006ERL
    5/16 - AT165056ERL

    You can use a TBI truck fuel filter (they used it into the LS Vortec years, so it can handle the higher pressure). You'll need to adapt it from 16mm o-ring to -AN (you'll need two adapters). PN for that is AT991955ERL.

    You'll need some miscellaneous AN unions, tube nuts, and sleeves to finish everything up, but that's a basis to get you going.
     
    Last edited: Oct 19, 2016
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  13. 86K1o

    86K1o Junior Member

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    Alrighty so i'm going to put in an order for fuel parts and this is whta I have so far:
    1987 R10 Fuel Tank
    1987 Fuel sending unit
    Walboro 255 gss342 fuel pump
    3/8 to -6AN QD is Russell 644123 (feed)
    5/16 to -6AN QD is Russell 640863 (return)
    Fragola Hose assemble AT165056ERL (hardline to rail feed)
    TBI truck fuel filter(dont have PN yet, if anyone would suggest one)
    2 of the AT991955ERL fittings to adapt it from 16mm o-ring to -AN

    And I believe my truck doesn't have a return line but I'll check tonight.
    Again, Thanks a lot everyone!
     
  14. putt2014

    putt2014 Junior Member

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    dual tanks



    Then what's the best option to run dual tanks?
     
  15. putt2014

    putt2014 Junior Member

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    Does ps pump, alternator or ac compressor need to be relocated on a ls for a K10/V10 swap? Are there any clearance issues with any of these. Have read where it is best to go with a camero ps pump. Basically what fits best? I appreciate all the help and info I have gotten from this site. Hope when I am done with my swap (5.3 in a 87 V10) I will be able to pass some knowledge along.
     

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