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TBI Fuel Line Options

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by BadDog, Nov 4, 2001.

  1. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    Ok, I'm tired of fooling with this fuel system. This is my first attempt at anything like this Diesel to 350 TBI conversion. I thought the best thing to do was keep all the factory stuff so that parts are easy to find, everything works together, and reliability. Maybe not.

    I got the fuel lines with my TBI tank and it ends up with the blasted fuel filter EXACTLY in the narrowest part between the frame rail and the 205! Argh! Only about 1/2" clearance with the passenger side exhaust. What jackass engineer decided to rout the fuel lines down the passenger side (along with everything else) and THEN across to the driver's side tank! You can't even change it easily because they use hard lines out the back of the TBI down to the passenger side of the bell housing.

    So, what is the best course of action here?

    Things I've considered:

    These lines that tie into the back of the TBI have the O-ring fitting on both ends, male on top, female on bottom, with the upper half hard line and the lower is braided line. I was thinking of trying to re-rout this down the driver's side. Looks like a real pain. Maybe taking the O-ring ends at the TBI, cutting them off a few inches back, flipping it to point to the driver's side and having standard AN fittings attached so I could run braided all the way down and back. It would be a real pain in the but to try to bend hard line to clear and go down the driver's side.

    Also, if I recall correctly, TBI runs at something like 13-15 PSI. This should not require anything like the factory system to function properly and hold up. Does it really need all this hard line/braided stuff? Or could standard high pressure rubber lines and clamps be used? I noticed that coming off the tank there is a high-pressure rubber line with a double clamp. Seems like I could use that and just rout the whole blasted thing down the outside of the frame rail on the passenger side without changing the stuff on the engine.

    Or, maybe use the O-ring fitting from the factory line, cut it off and attach a compression fitting to tie into a generic hard line, run it down the frame rail. The fuel filter could be spliced in-line the same way, with compression fittings. It would still need the rubber hose to bridge to the gas tank though.

    Sorry to ramble, these are just some things that I was thinking about today after giving up on the factory stuff. Any suggestions appreciated. I just thought I would see if anyone could (1) save me from doing something stupid and wasting time/money and/or (2) come up with a better idea. I'm frustrated and fed up so my thinking may not be very clear.

    Russ

    85 K30 CUCV, 350 TBI, TH400, 205, D60/C14, 4.56 Locked
    Some day: 4" lift, 44" tires, massive cutting, shorter wb and rear overhang.
     
  2. pcorssmit

    pcorssmit 1/2 ton status

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    I'm pretty sure my fuel filter is on the outside of the frame on the passenger side, kind of near the back of the door. I didn't get the lines of the truck my motor/tank came out of, I used the one of the stock lines (pretty sure it was the feed line), and replaced the other (as I recall, the stock diesel return line is only a 1/4", and should be 5/16 for TBI. I used normal hard line with inverted flare fittings. The adapters for the braided line (off the motor) were a PITA to find.

    I would definitly use hardline, not rubber or braided for long spans. It is fine to use short sections of fuel injection rated rubber hose and hose clamps, the factory setup does and it helps isolate pump noise, among other things. As far as the fuel filter, I found one for a Caprice TBI that has barb fittings on it instead of the goofy metric o-ring jobs. There is supposedly one with inverted flare fittings, but I've never been able to find one.

    I swapped out my 6.2 4-5 years ago, and never looked back. In the end, the TBI is worth all the effort.

    Pete

    '83 K5, 350 TBI (ex 6.2), 700R4, NP208, Dana 60/14 bolt, 4.56s, Detroits, 3" lift, 15-39.5x15 TSLs
    '97 Dodge 2500 4x4 CC LB Sport, Cummins 5 spd
     
  3. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    Thanks, I generally run hard line for any spans. In fact, I just ran new hard lines for the tranny cooler to replace some rigged rubber lines. Getting all the fittings to work out on this just seemed like a real PITA. How did you connect the o-ring fittings (that screw into the braided lines) to the hard lines? Did you cut off some of the stock pieces and use compression fittings? Or cut off the stock ends and flare it for a normal flare coupling? Or did you find another way? When you said "the adapters were a PITA to find" it sounds like maybe you found a better way...

    Russ

    85 K30 CUCV, 350 TBI, TH400, 205, D60/C14, 4.56 Locked
    Some day: 4" lift, 44" tires, massive cutting, shorter wb and rear overhang.
     
  4. pcorssmit

    pcorssmit 1/2 ton status

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    I actually did find some adapters to go from i-f to the metric o-ring, I used these to connect the braided line off the motor to the i-f hard line. The only other place I have the metric o-ring is on the filter, for there I used a couple fittings I cut off some other GM car at the junk yard. We used the Caprice filter on my brother's '70 to avoid this. I've heard that the adapters are easier to find nowadays, but don't remember who makes the adapters. Maybe try one of the larger parts houses. Or you could just adapt it with a short piece of rubber hose.

    Pete

    '83 K5, 350 TBI (ex 6.2), 700R4, NP208, Dana 60/14 bolt, 4.56s, Detroits, 3" lift, 15-39.5x15 TSLs
    '97 Dodge 2500 4x4 CC LB Sport, Cummins 5 spd
     
  5. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    I'll see if I can find those adapters. Even to use a rubber hose I would need to get a nipple attached somehow, I wouldn't trust the hose to stay on a smooth tube. I guess I could rent an inverse flare tool and flare the lines I have about 2" behind the o-ring nuts to make my own adapter. If I can't find an adapter (or if they like them too much [​IMG]) I guess I will just do that. Then a flare coupling to go into hard line and run it down the out side of the rail. Same thing for the filter. Then flare to fit a nipple and jump to the tank with rubber.

    Thanks for the suggestions and info.

    Russ

    85 K30 CUCV, 350 TBI, TH400, 205, D60/C14, 4.56 Locked
    Some day: 4" lift, 44" tires, massive cutting, shorter wb and rear overhang.
     
  6. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    This is just an update as an FYI for anyone else who starts a project like this.

    I never did find those adapters. I also tried several parts houses (NAPA, Checker, AutoZone) for the double barbed fuel pump with no luck. Late 80's Caprice has shows the same filter I have with double O-ring nuts. Closest I could find was one with a single barb and an O-ring on the other side.

    So, I eventually gave up and made a set of adapters out of the lines I have. Now, I can easily tie into normal flared hard lines from any parts house. Only problem was that one of them was too short (went into a high pressure rubber hose on the fuel pump output) without enough straight section to flare with the nut on it. So, I went down to a local "tube and hose fabricator" shop and had them weld a standard fitting on the end so that I could screw on a barb. I'll use standard clamped FI gas hose slipped onto a pair of barbs instead of the permanent crimped hose that was originally there.

    I even took a <a target="_blank" href=http://members.home.net/russhuffman/Adapters.jpg>pic</a> to post here for future reference if anyone else decides to do this conversion.

    Russ

    85 K30 CUCV, 350 TBI, TH400, 205, D60/C14, 4.56 Locked
    Some day: 4" lift, 44" tires, massive cutting, shorter wb and rear overhang.
     

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