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plumbing fuel lines for TBI

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Seventy4Blazer, May 27, 2003.

  1. Seventy4Blazer

    Seventy4Blazer 3/4 ton status

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    im going to be plumbing my fuel lines some day and was wondering if i could use steel braided fuel line throughout the system. i dont see why i cant, but i just want to double check. i know i have to have one out of the tank to the pump( this will be a fuel cell and a stan alone pump with a pre filter) to the tbi unit then back to the tank. also has to be a pressurized tank for the TBI correct?

    i also need a pressure regulator. the filter will be before the pump and one in the engine compartment as well. and a pressure guage.

    any thing i might be missing let me know.
    Grant
     
  2. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    Well, don't know if I want to help you now or not... <sniff> /forums/images/graemlins/rotfl.gif

    Tank is not pressurized.

    You could use braided, and I considered it, but I wound up bending new hard lines where needed. If you search back a year or so, I posted a similar question and was convinced that the hard lines were the right thing to do...

    Stock TBI has the regulator build into the TB. Shouldn't need one inline unless your trying to run a TPI pump or some other very high pressure pump...

    Pumps don't like to suck, so you need to put a very low restriction filter in front of the pump (similar to the stock sock I would think?). I much prefer the in tank pump, but, much the same as in cage mounting theories, most seem to disagree...

    I'm no expert so, take it with a grain of salt, but that's what I think I know...
     
  3. azblazor

    azblazor 1/2 ton status Premium Member

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    Standard rubber fuel line is fine for TBI. It is rated for 50PSI working pressure rating and 250PSI minimum burst pressure rating.
     
  4. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    Oh yeah, forgot to add that, I've got rubber EFI hose from the tank (in tank pump) to the hard lines. Just don't run common gas line hose...
     
  5. dyeager535

    dyeager535 1 ton status Premium Member

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    I'm curious actually...great that everyone knows the burst rating, but whats the temp threshold, and whats the rated lifetime at X temperature under Y pressure, assuming ideal conditions, such as no abrasions from vibration against steel and what not for rubber hose? (actual braided/teflon inside lines look to be pretty good, but really pricey)

    I don't believe rubber line is a good idea ANYWHERE on a vehicle unless it HAS to be, such as the transition from frame rail to engine, or sending unit to frame rail.

    I'm not ragging on anyone, I know there are plenty of people out there that have no problems, but you also see plenty of people out there that burn their vehicles down, and plenty of people that have rotten *rubber* vacuum hoses. I don't/won't play around with gas, oil, or tranny fluid supply near sources of heat and/or combustion.

    Thats all my *opinion* though, so do what you like. I'll take my fuel line ideas from GM.
     
  6. Seventy4Blazer

    Seventy4Blazer 3/4 ton status

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    russ, im going to reply to you and everybody else at the same time. the tank is going to be mounted in the bed of my blazer. WAY in the back. it will have a aluminum box built around it. and i think i will rig up a remote fire putter outter up to it, for that guy justin case(yall know him right, comes by at the worst of times.)

    all the plumbing, no matter what i end up doing will be protected by a nice peice og angle iron. this way anything in the bed will be safe. since our used to be local guy doug has a 40 gallon fuel tank out of a 90 burban for me i will be using that. it will be bolted to the roll cage via rubber bushings. filler cap will be har mounted to the roll cage. this way i get to decide what side i want it on as well... he he WHOO HOO...

    i agree that the rubber hose should be used as little as possible. i have no problem bending hard line, especialy for the cost of steel braided. but i LOVE the way steel braided looks. the red and blue -AN fittings just do it for me.

    since i now found out i will be running a stock style tank i wont need the fuel regulator or the aftermarket filter before the pump as i will be running a stock pump. i will however put a glass filter before the TBI unit.

    nobody did answer one of my questions/commnets... only 2 lines into/out of the tank on a tbi? and then a vent since its not a pressurized tank?

    thanks gus for all the good info.

    keep it comming.
    Grant
     
  7. dyeager535

    dyeager535 1 ton status Premium Member

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    Actually I think it's 3...

    Fuel feed, fuel return, and the EVAP line.

    I'd suggest plugging the evap line at the tank, and running an older "vented" gas cap. Later ones are vented too, but at a higher pressure. Either that or run the EVAP system, but that gets kind of complicated.
     
  8. Seventy4Blazer

    Seventy4Blazer 3/4 ton status

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    evap line... charcoal canister?
    Grant
     
  9. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    Yep, that's what he's talking about. I just ran my evap line to the filler (my stuff is all mixed up from multiple years) and a cap from a 78(?) Suburban that donated the filler neck. The filler neck was welded onto the end of a piece of roll bar tube that was bent to put it where I wanted it (safe and easy access) and a tab was welded to the frame to support it. It does not mount to the cage, though it looks like it does, it move with the frame/tank and there is no stress or movement on the very short hose jumping to the tank inlet.

    So, on my tank, there is the large inlet, HP out, LP return, and evap to filler neck...
     
  10. dyeager535

    dyeager535 1 ton status Premium Member

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    Yeah, EVAP is charcoal cannister. It's not a bad idea, but since it's "switched" (not a direct feed to the engine) if you wanted to plumb it correctly, it would mean adding more hoses in the engine bay.

    You could probably run the line up to the cannister and leave the cannister unplugged, but again, might as well just plug the line and run a vented gas cap. Besides, gas vapor vented into the engine compartment is a no-no to me.
     
  11. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    But he needs to make sure there is still a vent line to the filler, or it's a PIA to fill up. The stock K5 tanks on most years have the vent in the sending unit. When replaced with an EFI sending unit, that vent is not there (at least not on the one I used which came from an 87 SWB TBI pickup). I had to remove the valve from the evap line and plumb it into the filler neck. First try I left the sending unit unmolested and it took 20 minutes to fill up that small tank. Now, wide open to full...
     
  12. dyeager535

    dyeager535 1 ton status Premium Member

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    [ QUOTE ]
    But he needs to make sure there is still a vent line to the filler, or it's a PIA to fill up.

    [/ QUOTE ]

    Hmm...

    I never thought about it, so never looked!

    On the TBI tank that I bought new, the little "tab" that the fill vent line runs through is present. But I've never looked that close at the sending unit. ('88 TBI K5)

    That very well may be a difference on the pickup vs blazer tanks: LMC pickup tank pic LMC blazer tank

    On the pickup tank you can see what looks to be a fitting on the side for the fill vent. I'm 99% sure my dads saddle tanks are set up the same way, with the vents seperate of the sending unit.

    The Blazer tank fill vent very well may be integrated with the sender. Hope so! Can't find pics of a TBI K5 sender to check.
     
  13. azblazor

    azblazor 1/2 ton status Premium Member

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    I know that just about everyone on this site who has ever posted on this subject, tends to dissagree with using standard fuel line [50PSI WPR (working press) and 250 MBPR ( min burst press)] on TBI systems. That is why I have never really posted about my opinion, people tend to get somewhat hostile and say things like "how could you NOT use fuel line that was specifically intended for fuel injection for TBI" or "don't you care about safety?"

    Well, just to make clear my position on TBI fuel line. TBI fuel pump pressures ( aproximately 15 PSIG - usually lower )do not require (in my opinion) "Fuel injection" rated rubber fuel line (125 PSI WPR). TBI pressures are only slightly higher than a carbureted system. Using hard fuel line is always "more is better". But that said, I have used significant runs of "standard fuel line" in systems I have. I let my children and my wife drive these cars and they are safe. (Lets not get into personal attacks please)

    So if you want to spend more money to raise your safety margin by buying high pressure fuel injection line - thats OK. But in my opinion having a 3-4 safety margin at maximum working pressure, and a 16-17 safety margin at minimum burst pressure is an adequate allowance.

    I also make the argument that proper maintenance and replacement of the fuel line is more important than using high pressure line. Someone who spent several times more for high pressure fuel line could use that fact to be a little complacent about inspections, minor damage and replacement.

    I have had other people who happen to do these conversions commercially tell me the same thing about using "standard fuel line", that they think it is completely acceptable.


    Just for the record, I know a little about containing various substances at various pressures in various kinds of tubing. My profession is "instrumentation and controls". I have been specifing and procuring, installing and maintaining, processs, hydralic and sensing lines from 3 PSIG to 6000 PSIG for almost 30 years, for US Navy Nuclear Submarines and the Commercial Nuclear industry. My point is that I have some feel for safety margins. And the kind of margins I am talking about are as good or better than many nuclear systems involving substantially higher pressures.

    There, I have done it - laid bare my terrible secret /forums/images/graemlins/smile.gif
     
  14. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    [ QUOTE ]
    There, I have done it - laid bare my terrible secret /forums/images/graemlins/smile.gif

    [/ QUOTE ]
    Don't worry Mark, we're here for you and we will help you through this. Just keep saying "more is better, more is better..." /forums/images/graemlins/rotfl.gif

    Seriously, sounds like you've got the qualifications to back up that decision. Still, I'm glad I opted for hard lines. Practically no concern for abrasion or damage as long as it's secured (I used factory strap loops). Not much more expensive (if any) than rubber line (and cheaper than EFI hose) and it's not hard to run and secure. <shrug> Also, I can run EFI rubber line for next to nothing to jump since I only need 6" or so. But then again, I have hard lines on the trans, cooler, radiator circuit too. "More is better, more is better, ..." /forums/images/graemlins/wink.gif
     
  15. mosesburb

    mosesburb For Rent Premium Member GMOTM Winner

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    Hey Grant,
    I used -06 braided lines on my Nova when I converted it to TBI years ago. I have had no problems with it at all. These days you can actually purchase adapters to go from your metric o-ring fittings in the fuel pressure regulator to go to the -06 fittings. I used the regular stainless braided/silicone hose on the fuel and return lines. I have only used the braided/teflon on my p/s pressure lines so far (they are a royal bitch to build compared to building silicone/braided lines). Earl's and XRP make the o-ring to -06 adapters and I'm sure others do as well (I had to make my own adapters, because in the early 90's no one made/stocked them, but now they are quite readily available). I can get you some XRP p/n's if you need them.
    Good luck,
    Nick
     
  16. BlazerGuy

    BlazerGuy 3/4 ton status

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    [ QUOTE ]
    for that guy justin case(yall know him right, comes by at the worst of times.)

    [/ QUOTE ]
    Yeah, not to mention his sonofabitch brother, Mister Murphy! If I ever find that guy I'm gonna kick 'im in da sack!!! /forums/images/graemlins/deal.gif /forums/images/graemlins/rotfl.gif /forums/images/graemlins/rotfl.gif /forums/images/graemlins/thumb.gif
     
  17. Seventy4Blazer

    Seventy4Blazer 3/4 ton status

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    nick, thats good to know.
    those part numbers would be great. and maybe a web site?
    thanks for the info. since i make a few hydraulic lines here and there("illegaly" for our aircraft at SAR) i know how to manupulate the teflon lined steel braided rubber hose. i also need to find adaptors for the powersteering to convert to and -AB 06 as well. but thats another post.
    Grant
     
  18. mosesburb

    mosesburb For Rent Premium Member GMOTM Winner

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    Yeah sure. The catalogs I have on that stuff is at home. I should be able to post it later. If you're in a rush try a search for "Earl's Fittings" and/or "XRP Fittings". The catalog should have a website on it, so I can post it later as well.

    On your P/S box and pump, are they inverted flare or o-ring?? Both adapters are made, but need to know what you have.

    Silicone braided will be overkill for your fuel lines and will be more than sufficient for your P/S return line, but the P/S pressure line needs to be made in the teflon braided for any kind of reasonable life expectancy (I figured this out the wrong way /forums/images/graemlins/rotfl.gif). So, anyways, I will post you back later on with your desired info /forums/images/graemlins/thumb.gif.
     
  19. mosesburb

    mosesburb For Rent Premium Member GMOTM Winner

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    Here is the info you requested:
    The following info is for XRP brand fittings.
    P/N's 79xxx are aluminum, 49xxx are steel for the metric applications
    14mm X 1.5 791415/491415
    16mm X 1.5 791615/491615
    18mm X 1.5 791815/491815

    14mm is your TBI return line fitting
    16mm is your TBI pressure fitting, and your P/S pump fitting, and your P/S box return fitting
    18mm is your P/S box pressure fitting
    P/S info is assuming you have a o-ring style pump fitting/box fittings. If not, the inverted flare info is as follows:

    5/8-18 790126--P/S pump fitting, and P/S box return fitting--this is for a steel fitting
    11/16-18 791166--P/S box pressure fitting--this is a steel fitting (I don't know why the 79xxx series are steel in this application, but this is how the catalog lists them)

    You can check this out for yourself at www.xrp.com or by calling 562.861.4765. See if you can request a print catalog.
    I know Earl's makes this stuff also, but being that they were purchased by Holley, you stand little chance of obtaining them, because Holley's ordering system leaves just about eveything to be desired--absolutely terrible /forums/images/graemlins/frown.gif.
    Let me know if I can be of any further assistance /forums/images/graemlins/grin.gif.
    Good Luck,
    Nick
     
  20. Seventy4Blazer

    Seventy4Blazer 3/4 ton status

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    thanks man. wow, got a lot of good info there. im sorry i didnt tell ya what kind of box i had. i mean to go look, but never got to it, busy day.

    ill let ya know how it turns out. but it will be a while.
    Grant
     

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