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My dual tanks are pissing me off

Discussion in 'The Garage' started by k20, Oct 14, 2004.

  1. k20

    k20 3/4 ton status

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    Hey guys, being with only one tank is starting to suck. Look down this morning got 1/32 of a tank
    /forums/images/graemlins/yikes.gif<--------me this mornin

    Ok, heres my application. I have the stock TBI in tank pumps, the stock TBI diverter valve, and an edelbrock frame rail booster pump on the frame rail (to boost to 45-50psi for the MPFI). Anyway, if I run off the drivers side tank all is fine, but I switch to the pass side and the edelbrock pump begins screaming. I mean a whinin sound, I can here over my exhaust and 800w stereo. Ive changed the tank switch on the dash, changed the diverter valve 3 times (gotta love warranties) and changed the pass fuel pump twice (gotta love warranties).

    Heres the plan. I get 2 late model (96 97 whatever) pumps (high pressure cause these are mpfi) drop em in the tanks. Then, because I doubt the stock diverter valve can take that pressure (there are different ones for the carb vs tbi trucks) put in a manual diverter valve. Either cable or lever activated.

    Now my question is, would this work, and just leave the stock wiring to turn the pumps on and off and then manually switch the tank? Or could I get a late model diverter valve, and make it work? Would the wiring be anywhere close to the same, and if not, could anyone give me some info on what I would need to wire it up. Id prefer to stay fully electric switching, but this problem is pissin me off.

    Ive got the factory manual and have done all of their tests, and everything says that its working fine, it just aint working well. Even traced the wiring best I can, and it all looks fine.

    Thanks guys.
     
  2. Leadfoot

    Leadfoot 1/2 ton status Premium Member

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    It sounds as if there is a problem with the passenger's side tank, lines, or the problem lies in the design of the diverter. You said you changed out the passenger's side fuel pump (which I believe is mounted in the tank) so you should have seen if there was any crap in the tank or on the pickup screen. Since that is not a problem, you might want to check/replace any flex line from the pass side tank to the diverter valve (maybe sucking in on itself) or check for restriction in any plumbed pass side hardline. If that is not the problem I would get some flex fuel injection hose and bypass the diverter valve and go directly to the Edlebrock pump on the passenger's side (effectively diagnosing a diverter valve issue). There could be an inherent problem with the diverter valve as it designed to work with stock TBI pumps supplying it without having to feed a booster pump. The other thing you could try is swapping the inlets on the diverter valve and see if the problem switches sides. My .02
     
  3. k20

    k20 3/4 ton status

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    tank didnt have any crap in it, the old screen on the pump looked pretty clean. The line from the tank to the diverter valve are metal except for like a 2 or 3" piece of rubber, which is almost all on the plastic nipple of the valve. I dont see how the 1/2" piece not on the nipple could suck shut. I might try and switch the lines and see if it switches sides. If it does....what does that tell me?

    I mean this is the 3rd valve thats been on it, and I can make it switch in open air (had line off and just plugged in) and it would switch, could blow through one way, not the other, hit the switch, cant blow that way, can the other.

    Yeh I may try running the feed line from the tank over to the edelbrock pump, bypass the diverter see whats up. If that fixes it, again what does it tell me, and if it dont, I assume the pump isnt supplying enough volume, and Ill need to get a GM ($$$$$$$$$$$$$$) pump, and not an aftermarket.
     
  4. diesel4me

    diesel4me 1 ton status Premium Member

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    Could you tee both tanks together??--then it would be like having one BIG tank!--or do you want to keep the option of draining one tank dry,then switching to the other?. /forums/images/graemlins/thinking.gif
    My dual tanks on my 82 diesel pissed me off too--when the drivers side started leaking the first time I filled it!--now its running on only the right side tank--I removed all the mickey mouse plumbing and manual tank valves the previous owner put in(the factory dual tank switch and its wiring and the dash switch were all missing!)--I dont drive that far anyway,and 20 gallons of diesel will last for about 350-400 miles,so I might just remove the leaky one to save a little weight.
     
  5. k20

    k20 3/4 ton status

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    no, I want to keep the option of draining one tank, I always look at it as a fail safe in case I rip a hole in one offroad, (and i dont catch fire lol) I still have another tank to drive out on. T'd together itd be suckin air.

    Another anomoly I forgot to mention is that when it does the whining thing, the fuel level in the passenger side tank doesnt display. I can hear the pump in the pass side turn on, so it is pumping (possibly not enough) but it doesnt display level. Atleast in the time I leave it on that tank the gauge wont move.(I dont like to leave it on that tank too long so it wont overheat the booster pump)
     
  6. 1-ton

    1-ton 1/2 ton status Premium Member

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    [​IMG]

    Here is your answer. Bolt this 45 Gallon tank into the bed of your truck, and get rid of the exploding saddle tanks. You will also eliminate all the excess fuel lines, wiring, and fuel tank selector switch.
     
  7. ntsqd

    ntsqd 1/2 ton status

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    [ QUOTE ]
    Since that is not a problem, you might want to check/replace any flex line from the pass side tank to the diverter valve (maybe sucking in on itself) or check for restriction in any plumbed pass side hardline.

    [/ QUOTE ]

    What I was thinking, but I'd just replace it with fuel injection hose. It doesn't take much length to get a flapper, and those will drive you nuts trying to diagnose.

    Interesting thot about the booster pump possibly pulling a vacuum on the valve. Manual valves are out there. One application is an Early Bronco with dual tanks. My grandad used one of those on his pick-up. Then he cut a a slice out of some 1" round stock and drilled a hole in it off center. Thru the side he drilled an tapped for a set screw. Put that on the stem of the valve and used a micro switch against his cam to switch the gauge when the valve got switched.
     
  8. BrianDamage

    BrianDamage 1/2 ton status

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    [ QUOTE ]
    [​IMG]

    Here is your answer. Bolt this 45 Gallon tank into the bed of your truck, and get rid of the exploding saddle tanks. You will also eliminate all the excess fuel lines, wiring, and fuel tank selector switch.

    [/ QUOTE ]

    I don't see where that would be any safer ? It sits right in the bed, where a saddle tank has the sheetmetal fenders over it ?
     
  9. k20

    k20 3/4 ton status

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    Hey guys, ok, well I been playing w/ 93 octane this morning, so bear with me. I hooked the passenger side tank directly to the main fuel line, and it doesnt seem to be making the extreme amount of noise that it was. This thing is driving me nuts. Called the chevy dealer, the diverter valves are the same through 90, then they change, and he said they stayed the same from there on out (i find that hard to believe, I think it was quittin time). Anyone got anymore ideas? Seems to be isolated to the fuel diverter valve(this is again, the 3rd one thats been on the truck, 1 OE, then 2 new chevy pieces).
     
  10. 1-ton

    1-ton 1/2 ton status Premium Member

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    [ QUOTE ]
    I don't see where that would be any safer ? It sits right in the bed, where a saddle tank has the sheetmetal fenders over it ?

    [/ QUOTE ]

    [​IMG]

    The sheetmetal fenders do nothing for protection. I could kick those and bend them with my boots. If I can do that, then what makes you think that being broadsided by a vehicle doing speed limit (or faster) is going to protect it? Factory fuel tanks are only made with 1/16 inch thick sheetmetal, but the fual tank I was refering to is made of 1/8 inch thick diamond plate aluminized steel, wich can take one hell of a hit before it will open up. Also, when a fuel tank is in the bed, it is protected by not only the fender sheetmetal, but also the sheetmetal inside the bed. That makes two layers of sheetmetal, as oppossed to one.
     
  11. diesel4me

    diesel4me 1 ton status Premium Member

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    Maybe try an aftermarket valve-?-Standard Ignition makes 2 different ones,one for wehicles with return lines,and one without--the one with has 6 ports,the one without has 3 I beleive.I decided to do away with my duals on the diesel for another reason also--they often let the fuel system suck enough air when switching tanks, and the truck wont re-start without a lot of bleeding and frustration-They also seem to fail or screw up qwite often,manual may be better choice than an electric valve-I like having one tank,and a simple fuel line filter and electric fuel pump.The wiring,switches and all the plumbing for the factory dual tanks was missing,seemed too complicated for me to figure out the wiring,and buy all the new switches(if they even sell them anymore)--wasnt worth it to me,I got the fuel gauge to work on the one non-leaking tank--good enough for me! /forums/images/graemlins/crazy.gif
     
  12. 3 on the tree

    3 on the tree 1/2 ton status

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    Does your system require return lines for each tank? If so, are they clogged? Thats what happened to my 88 Ford with dual tanks. /forums/images/graemlins/dunno.gif
     
  13. k20

    k20 3/4 ton status

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    yeh, returns are fine though. I fired off an email to edelbrock, maybe ill get a response, and someone else has had this problem *crosses fingers*
     
  14. oldtoyboyd

    oldtoyboyd 1/2 ton status

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    Are you sure you dont have the intank pump wired backwards and it is pulling against the inline pump when you switch tanks, especially since you said the gauge isnt working.
     
  15. k20

    k20 3/4 ton status

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    pretty sure, if it was wired backwards, I would think it would lose more than 2psi of fuel pressure, and the truck will keep runnin, just the pump starts makin all kinds of noise.
     
  16. Super M

    Super M Newbie

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    Did you ever get this problem figured out? It sounds similar to a problem I am currently having.
     

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