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Replacing TBI w/ Carb

Discussion in 'Performance & Fuel' started by bigbluesub, May 18, 2010.

  1. bigbluesub

    bigbluesub New Member

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    Greetings all, I was wondering if anyone has replaced their TBI w/ a new carb and intake. What do you do with the current fuel lines? Does the fuel pump need to be regulated? Does the throttle linkage work? Will the gas pedal still work and what about the tranny kickdown?

    Also, who has replaced their TBI with a new Holley unit and how did that work out for you?

    Thanks,
    jesse
    #1
  2. dualdj1

    dualdj1 New Member

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    There are generally adapters/etc to make your linkages fit/work. Not positive without digging on your specific model.

    You will most definitely need a pressure regulator, or have to convert to mechanical pump. Carbs are about 7-9psi, and IIRC the electric pumps on those will push up to about 20psi. The other option would be switching over to a mechanical pump, and eliminating the return. Mech should be strong enough to pull through your existing electrical if you just disconnect it (or so I've heard). All in all probly cheaper and more reliable to just get a regulator.
    #2
  3. murdog94

    murdog94 New Member

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    From what i have heard the Holleys work great. Im not 100% since i havent used one however my 1988 K2500 has a Holley on it but it seems to be stock... Why are you thinking about changing the TBI out if you dont mind me asking??
    #3
  4. bigbluesub

    bigbluesub New Member

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    I'm having some trouble with the way it runs, stumbling, hesitation and stalling, but not all the time. Sometimes it runs great. I was just pricing my options when i noticed i could replace the TBI with a carb and intake for about the same money. And who doesn't like a four barrel!!!!
    #4
  5. murdog94

    murdog94 New Member

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    Do you have a CEL?? And as for the hesitation.. you might consider a tune up?? Especially the fuel filter.. Mine had a bunch of black goo in it. Also clean up the TBI and consider a fuel pressure regulator.. That will help dramatically.
    #5
  6. kburb

    kburb New Member

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    #6
  7. bigbluesub

    bigbluesub New Member

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    Hmmm, I have new plugs,wires,cap & rotor. Just installed Long tube headers and crossover pipe. It has had the problem all along........ I have also changed out the fuel filter and the tps.......
    I'm wondering if it could be a vac. leak in the manifold, I hear they are known for that.......
    #7
  8. bigdogdaddy

    bigdogdaddy New Member

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    Did you try replacing any of the sensors? Also, do you get a check engine light? My 90 had this problem and I replaced all the sensors and the EGR, and it runs like a raped ape. The only prob I have is a broken/burnt wire on the ESC (Electronic Spark Control) solenoid signal wire, but I'm re-running that to fix it. I was going to replace mine, but TBI's done right will hang right with, if not beat the best tuned carbs any day.
    #8
  9. murdog94

    murdog94 New Member

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    Try a new gasket around the TBI.. and possibly remove the TBI spacer, and with the new gasket to see where you are.. I am suffering from a lack of power.. and every thing that i have changed has helped.. but currently i am at the fuel pump.. Just remeber this the TBI is more efficent and actually easier on the motor because the motor is always getting the right air/fuel ratio, and with a carb you can only really have 1 jet size, causing you to only be "close" all the time instead of right on.
    #9
  10. bigbluesub

    bigbluesub New Member

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    All good stuff, thanks. Guess i will get my codes scanned this weekend and go from there.......
    #10
  11. dualdj1

    dualdj1 New Member

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    I also would recommend staying with TBI. Double check all your wiring to make sure you don't have a short somewhere. Other than that you may have a partially plugged injector, run some good fuel system cleaner though it too.
    #11
  12. bigbluesub

    bigbluesub New Member

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    I pulled my codes...

    with a paper clip. This is what I got:

    12
    13
    43
    44

    Can anyone help me with what they mean?
    #12
  13. trapperdon

    trapperdon New Member

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    code 12 is the system computer code test signal telling you that the
    diagnostic test was completed correctly. you will always get that one.

    13 is oxygen sensor signal fault - signal too low / open left O2 sensor circuit ( dual sensor models )

    43 is electronic spark timing ( EST ) circuit - low voltage detected
    or electronic spark control ( ESC ) - circuit problems

    44 is lean exhaust indicated ( left side on dual oxygen models )

    **************************************************************

    ok, did you unplug the timing bypass wire when you did the tuneup & timed it?
    did you verify that the adjustment screws on the tps is set at the right angle? a little off means alot

    did all the probs start AFTER you put on the headers & crossover pipe ?
    your O2 sensor might not be reading the new exhaust values
    #13
  14. bigbluesub

    bigbluesub New Member

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    ok, did you unplug the timing bypass wire when you did the tuneup & timed it?
    No I did not......

    did you verify that the adjustment screws on the tps is set at the right angle? a little off means alot
    Again, no.......

    did all the probs start AFTER you put on the headers & crossover pipe ?
    your O2 sensor might not be reading the new exhaust values
    no, I was having the problems since i got it in September......

    Thanks for taking the time to respond!!
    #14
  15. cameronc

    cameronc New Member

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    I dont know if this helps but I have been through the same thing on my 89 4x4 5.7. It was running terrible so i purchased a holley tbi. It didn't help at all. I switched mine to a carb setup and i love it but there is more to it than you think. Of course the carb & intake. A pressure regulator will not hold up on your factory furl pump when your cutting the pressure down to 4-7psi. I found that out the hard way, It blew apart. So now you have 2 choices. You can get a mechanical pump and bolt on to your block, if you buy one for a 85 chevy truck it will have a return line on the pump, if you plug off the return it WILL vapor lock. You can also go to your local parts store and buy a 12volt pump that pumps 4-7 psi for about $40. Thats pretty simple also. As far as pulling through the tank, you will have to remove your fuel pump and replace it with a pickup tube such as a brake line. It WILL NOT pull through the pump in the tank. For connect your fuel lines - there is 2 special fittings in the back of your tbi that screw out. Ony these fittings will fit on your factory fuel lines so take the fittings out and leave them hooked onto the factory lines, then you can take 3/8 fuel hose and push up over the ends of the threads and clamp them down, the threads will act as a lock so they wont slide off, you can do your suction & return this way. Another thing is the cam, if you switch to a carb you may not be satisfied until you swap cams because a ecm controlled efi cam is way different than a carb cam. You must also get an HEI distributor and do away with the computer controlled setup all together. I just tucked all my wiring harness under the firewall because I didnt want to go hacking on a wiring harness. Im sure i forgot something so if you need any help just get up with me.
    #15
  16. kidashley25

    kidashley25 New Member

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    pull the fuel pump out of the tank and replace it with a pick up tube. add a in line low pressure pump powered by the same wires your old one used. careful not to dis connect the fuel Gage. swap the intake with a new style carb intake. the old styles will not work. add a carb and viola. It now runs on a carb and will need constant adjustment.

    ________________________________________________________________________________________
    Dodge Durango Parts is available in five trims: ST, SXT, SLT, Adventurer and Limited. Base engine is the 3.7 liter Magnum V6 engine while the 5.7 liter Hemi V8 engine was available for higher trims. A 5-speed automatic transmission is standard for all trims and packages.
    #16
  17. bigbluesub

    bigbluesub New Member

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    Wow, all the little details add up. I will try and trouble shoot what the setup I have....
    #17
  18. bigbluesub

    bigbluesub New Member

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    Okay, here is the latest. I uplugged the timing advance wire and advanced the timing a little and re connected the wire. The truck ran great. no more stalling, no more loping at light throttle. It ran great for two days so I took it to work today (80 miles round trip) coming home, it was pinging like a mo-fo. I could hardly drive it. I unhooked the timing advance wire but it made no difference. Any thoughts about what the problem is now? Is there a knock sensor?
    #18
  19. bigbluesub

    bigbluesub New Member

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    Well after sleeping on it I checked this morning and a hose popped off the EGR valve. I didn't have time to test drive, but will give it a go this afternoon.
    #19
  20. dualdj1

    dualdj1 New Member

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    That could make a big difference. I'm assuming it was the vacuum line that came off?
    #20

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