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TBI Pump: In-Tank or In-line?

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. It's tough as @#$ to find a TBI tank that goes outside the rails. On top of that, I have yet to find a good one (without busted baffles).

    So, I'm looking for opinions/facts on fuel pumps/tanks. I've heard a bunch of stuff but how much is fact or fiction, I don't know. Maybe you TBI/EFI guys can put me on the right trail?

    So, why would I want it in the tank? In the tank is cheaper (about 1/2 the price), (supposedly) more reliable, and easier to find in your average parts house. Only problem is, it is hard to access, and hard to find the right tank.

    I shied away from using the diesel tank with an in-line pump for the following reasons. It costs about twice as much, so for the same amount I can put a new pump in the tank and carry an extra (which are already more reliable I'm told). In-line TBI pumps are also not readily available in your average parts house. One other thing, with the diesel tank, it seems I would still have the problem of running out of gas on extreme angles because there is no baffle.

    So, what do ya'll think? Is my thinking right? Have I missed anything? Maybe I should just get a fuel cell and put it in the bed? I'm guessing that would eliminate the baffles problem but I would need an in-line pump? Starting to wish I'd put a Q-Jet on this thing, I would already be driving it by now. [​IMG]


    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. DesertDueler

    DesertDueler 1/2 ton status

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    I would do an inline fuel pump. If you pump takes a crap you can put just about any aftermarket pump on there and make it work to get you home. Perfect example is the holley blue race pump. It puts out 12-14 psi, the same as the TBI in tank pump, and the holley pump is under $100. It also keeps you from having to buy another tank. As for th extreme angle thing just keep alot of gas in it.

    86Jimmy 4"&35"MTRs,87 burb 4"&35"MT,69Firebird w/525 hp,and 70GTO live in PHX,AZ<a target="_blank" href=http://www.geocities.com/modifierperformance>My vehicles</a>
     
  3. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    Someone mentioned the Holly Blue to me before but I was told (by several people) that it would not be able to keep the pressure high enough. Have you used it in a constant use application or, were you just talking about using it to "get you home"?

    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 don't see how running an external pump will be any different from an in-tank, as far as fuel starvation. I've helped 2 guys put in-tank pumps in non-FI tanks, one aftermarket tank in a CJ5 and one in a '70 K5. Both of them worked out ok, you just have to keep a little more gas in them than you would if you had baffles. This may work out a little different on a pickup tank, since they are so long. The stock sender can be modified to accomodate the in-tank pump. Either way you have to add a return line if you don't have one.

    I used to have a book on TPI/TBI swapping from JTR. I vaugely remember a secion in there on how to build a small external fuel tank that allowed you to run a non-baffled tank.

    If it were mine, I'd try putting an in-tank in the stock tank if you can't find a FI one. (Will a tank from a crew cab or maybe even a different type of truck work?) How much does a new tank cost?

    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. DesertDueler

    DesertDueler 1/2 ton status

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    It would work fine for constant application, just dont use the fuel pressure regulator. As for the holley blues holding up, the one in the firebird lasted two and a half years with the regulator hooked up and no return line. To make them last longer make sure and use a return, this allows the pump to flow more fuel through it and keeps it cooler, which makes them last alot longer. If you are worried about pressure being to low then use the holley black pump its 14 psi, more than needed.

    86Jimmy 4"&35"MTRs,87 burb 4"&35"MT,69Firebird w/525 hp,and 70GTO live in PHX,AZ<a target="_blank" href=http://www.geocities.com/modifierperformance>My vehicles</a>
     
  6. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    Well, the TBI tank I have was already going to require relocating one of the brackets (it is the short 87 tank). The brackets on it are about 3" closer together so using the diesel would save drilling 4 holes. I already looked at moving the sending unit to the diesel tank but the alignment tangs will not line up right (the TBI tank was pass side, diesel is drivers) so the tubes exit the wrong way. Probably simple enough to break out the Dremel and make some new notches I guess. But, the diesel tank is way to long to use when (if ever at this rate) the wheel base is shortened (which is why I grabbed the short tank). In my last several yard trips I looked at tanks from various sources (including a TBI blazer and a TBI inside the rail tank) but it just seemed like more trouble than my current troubles. I was also asking (couple of days ago) for ideas on fixing the baffles in my TBI tank (epoxy or something) but got no suggestions. LOL, problems, problems.

    So, you say "The stock sender can be modified to accommodate the in-tank pump". Do you mean use the sender plug from the diesel? I can see that the pickup could be cut off and the pump slipped on but, how do you get the power wire through? Drill a hole, run the lines, and seal it with RTV or something?

    Oh, didn't you say you used an upper radiator hose from some Pontiac to connect to the wide format diesel radiator? I have yet to find a hose that will work.

    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.
     
  7. pcorssmit

    pcorssmit 1/2 ton status

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    For the wire, you could do something like you said, or get/make some kind of electrical bulk-head fitting. I know one guy who used some nylon washers, all thread, nuts, etc. to do it. If you already have a TBI sendor, I'd try either using it whole or mix'n'match parts with the sendor for the tank you're using.

    The lower hose on mine is for the gas motor (I think). The upper is for a '72 Firebird w/a 400" motor. I have one of those chromy (yuk) water necks since its the only way to get one with an o-ring, I thought it was for a chevy, but now you've got me wondering if its for a Pontiac. Hmm. I had to stretch the opening on the radiator end. I bought an exhaust adapter for a buck or 2, then dipped the end of the hose in anti freeze and stretched it onto the adapter. I let it sit overnight and put it on the truck. Its pretty ghetto-fabulous. I've seen other people use two short peices of hose joined together by a length of pipe, as I recall Steve Watson used to have his that way. I may do that "next time". Either way, avoid universal flex hoses; they don't flow as well as molded ones.

    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
     
  8. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    Yeah, no flex hoses here and the lower hose from the gas motor worked out fine. I'll look specifically for that 'Bird hose tomorrow and see how it looks.

    I also thought about the "extension" route. My top hose misses lining up by about 6 inches. I thought about going to an exhaust shop and having them cut me an 8" piece to fit inside the hose. Then get them to swell about 1/4" of both ends just a bit so the hose clamp can lock against it. After a little file action to make sure the ends don't cut the hose, I'm thinking it would work ok.

    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.
     
  9. moneypit

    moneypit 1/2 ton status

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    Erie radiator in Boston sell brand new FI tanks 32 gal w baffles for a Bone shipped. If you need there # let me know and I will dig for my receipt. They also sell sending units for FI mine was $115 shipped.
     
  10. elkboy

    elkboy 1/2 ton status

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    After spending this weekend replacing a intank pump in the field, my recomendation is inline. Get a good marine (water proof) holly 12-14 PSI pump and stuff it inline. They use them for the TBI marine chevys and are very reliable and easy to replace. They will also work with just about any tank you want.

    <font color=red> Elkboy </font color=red> 82 K5 fuel injected H.O.305, TH350/205, 14bolt/10bolt and 39.5 TSL's.
     
  11. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    Your running a fuel cell now, right? Maybe I should just go ahead and jump to that. The saddle tank won't work anyway when I get the wheel base cut down (if I ever get to it). Are you running an in-tank with the cell? How do you like it (along with the other recent mods)?

    I guess that 32 gal must be a rear Blazer tank? If you have the number handy, it might be useful. All I could find is Erie Street Garage in Cambridge. No hits even on just "Erie" for Boston. Don't go to any trouble though, I think I have worked out what I'm going to do.

    I'm thinking that, for now, I'll just modify the diesel tank (which will go in easy - bolt in, no drilling or anything and the spout fits) to take the TBI pickup. Later I can try to come up with a better solution but this should work as long as I keep that big tank full.

    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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