78 Evinrude 70hp fuel trouble

Discussion in 'Bubba's Outboards' started by my4x4awd, May 13, 2007.

  1. my4x4awd

    my4x4awd New Member

    Messages:
    105
    State:
    TN
    1978 Evinrude 70Hp VRO. I rebuilt this engine 6 months ago along with new gas tanks, VRO pump and new oil tank and warning horn. Engine has run great every time since rebuild until Saturday. It is having a fuel problem I can’t figure out. After 1-2 minutes at full throttle. (I don’t know rpm because I can’t find a tach for it) engine will slow to a stop and die. No missing or popping. I have two tanks and checked the obvious, no water in gas, hard bulb and I use fuel stabilizer year round. If I keep squeezing the bulb it will run or if I slow down to half throttle it will run. I also cleaned carbs and the fuel filters and purged the fuel system. I have the carbs with the fixed high and low speed jets, no screws to adjust. The only thing that has changed is the connector on the fuel hose tank side. It was used and don’t remember before or after trouble started. I’m going to buy a new one today. Would a bad check valve cause this? Can someone help out?
     
  2. AwShucks

    AwShucks New Member

    Messages:
    4,532
    State:
    Guthrie, Oklaho
    Gadzooks, sounds like the old pin hole in the fuel diaphragm problem. Put a rebuild kit on the fuel pump. Stay tuned for BobPaul and/or Bubbakat.
     

  3. Bubbakat

    Bubbakat New Member

    Messages:
    4,532
    State:
    McMinnvill
    Change that fuel connector and try that to see if you are sucking air there instead of fuel. didn't you say you bought a new fuel pump and VRO togeather when you rebuilt it?


    To answer your question yes a check valve will act as you are describing here.
     
  4. my4x4awd

    my4x4awd New Member

    Messages:
    105
    State:
    TN
    Engine is 1986 model E70TLCDC. Yes I bought the updated VRO with the conversion kit so it is only six months old. I dont think it is loose but is there something inside that goes bad?

    Craig
     
  5. my4x4awd

    my4x4awd New Member

    Messages:
    105
    State:
    TN
    Sorry for another post my edit didnt take. Is the check valve the same as the fuel hose connector or is it something selse. I may have gotten the two confused.
    Craig
     
  6. Bubbakat

    Bubbakat New Member

    Messages:
    4,532
    State:
    McMinnvill
    The check valve is different from the fuel connector. But the connector can go bad and the thing will suck air in instead of fuel. A check valve has a ball inside to stop fuel from going back into the tank and when that ball corrodes it will stick in the closed position and some times in the half way mode preventing it from transfering enough fuel to the pump.
    You stated that you could squeez the bulb and keep running. That indicates a fuel blockage some where. Take the pick up tube out of the tank and take that little strainer off the end of it. Those things were a big problem because they were never big enough to start with.
     
  7. Bobpaul

    Bobpaul New Member

    Messages:
    3,039
    State:
    Supply NC
    A 6 month old upgraded VRO should last for yrs with no problem. There are checks you can do that are in the manual, but you'll need a small hand held vacume pump.

    Another thing you might try is a different remote fuel tank, just to try and isolate your problems. If you know someone with a tank and hose that'll fit your engine, then give it a try.

    You should've got a new pulse limiter with the new VRO, along with changing all the hoses. That's that little item that screws into the block and it's a blue and brass colored thing.

    If you know someone that can check that VRO out for you, get it done soon. If something's wrong with it, it may still be under warranty.
     
  8. daddio

    daddio New Member

    Messages:
    260
    State:
    kansas
    does your tank have a vent is it open or closed?
     
  9. Bobpaul

    Bobpaul New Member

    Messages:
    3,039
    State:
    Supply NC
    If his vent were closed, the bulb would suck flat and he wouldn't be able to pump it like he said.

    If your not getting enough fuel through the VRO, you'll get too much oil in the carbs and smoke like your foggin' for mosquito's. Is your engine smoking excessively?
     
  10. Bobpaul

    Bobpaul New Member

    Messages:
    3,039
    State:
    Supply NC
    Repost and give specifics of your engine
     
  11. jedt

    jedt New Member

    Messages:
    165
    State:
    Cameron,Texas
    My '77 85hp acted like that when I first mounted the motor to the boat. Found out had to set my idle and most of my other linkage in the water to get it right. Like bob said dang thing sound good on muffs but get them in the water and it is a different ball game.