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Fuel Delivery problem

Discussion in 'Chevy C/K Truck Forum' started by SPCMarty, Mar 20, 2010.

  1. SPCMarty

    SPCMarty New Member

    This truck has had new carb installed, and air cleaner, and the cap rotor, wires and plugs. now if i have the 6ga. red gas can hosed up to the fuel line. it connects with the fuel line where it becomes metal tubing just after the fuel tank selector valve. It runs just fine hooked up this way.
    now if i direct connect the driver side tank to the fuel line, bypassing the selector valve with fuel line hosing. the tank had 4-5yr old gas, i siphoned the old gas out, after i had used some gas already. it would cough and sputter after about 20mph, or cough out if i floored the pedal. I put a gallon and a half of premium with octane booster and water remover. It has more pick up but still coughs and sputters anyway.
    It just seems like it can't get the fuel it needs when the tank is hooked up. the passenger side tank line has been cut off before the valve.

    I don't know what else to do
  2. 71k-10

    71k-10 New Member

    Years ago I had a 68 Chevelle SS that would do the same thing, we changed many parts before we discovered a piece of rubber hose between the metal line and gas tank that was dry rotted and would suck enough air to make her cough and shut off under hard acceleration (in those days that was the only kind of acceleration that there was) She would restart in a minute, and it sure was frustrating.
  3. SPCMarty

    SPCMarty New Member

    So some where between the tank and metal line is more rubber hosing? I hope its something simple like that, really don't want to replace the tank/delivery piece
  4. 71k-10

    71k-10 New Member

    It cetainly is a possibility. I don't know that they all do, but that one did and we have a '95 4-runner that also does. Worth a shot. Since it works fine hooked up to a fuel jug, it would seem to me to be something "simple" maybe even some blockage in the fuel line. I will assume that you have checked or changed the fuel filter.
  5. SPCMarty

    SPCMarty New Member

    yes replaced the filter. it started to cough even when hooked to the small 6gal. A guy saw my truck struggling, and showed me how the 6gallon tank's air valve was shut. so it worked fine after opening the valve. So since i only bypassed the fuel line and not the vacuum line, i think that may be the problem
  6. 71k-10

    71k-10 New Member

    At this point it is all worth a try. I guess my point to this is to start with the easy small stuff first eliminate those things, then work up, hopefully you won't have to work up. Let us know how you are making out.
  7. SPCMarty

    SPCMarty New Member

    well, of the two lines going from the tank to the pump it seems the smaller of the two has fuel flowing through it. I thought the smaller one was the vapor return line? the trucks barely running this way.
  8. 71k-10

    71k-10 New Member

    I think it might be a return line, You should have lots of gas in the bigger line too. Maybe try some air pressure to blow those lines out (just to make sure there is no restrictions)
  9. KAHruzer

    KAHruzer Member

    I'm new to my Chevy, truck and the engines they use.

    BUT, most fuel systems are 'closed'. That is, entirely a loop circuit.
    Which means they are pressurized. Fuel delivery is via the pump
    which also causes the vapor return to function.

    Just guessing, but any air leak in the system means it doesn't
    properly pressurize. This could be a pin-hole in the filler pipe, a
    cracked line or ....a failing cap.

    My $0.02
  10. SPCMarty

    SPCMarty New Member

    Well we had it running well for a bit, it was vacuum related. but now once it warms up and is ran some it'll cough out. we're now thinking that one of the rubber hose connections is collapsing. Got a new pump and hose so hopefully that'll fix it.

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