94 evinrude 112hp cuts out at full throttle?

Discussion in 'Bubba's Outboards' started by tbull, Mar 30, 2008.

  1. tbull

    tbull New Member

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    3,318
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    SW Ohio
    Took out the new engine I put on the boat out today, thing ran awesome, plenty fast, sounded great, but here's the problem. Whenever I got to full throttle, about 10 seconds later it would lose power and die completley, you could hear it reving down and then would quit. The thing is I had my buddy sit back there, and as long as he kept squeezing the bulb it wouldnt do it, we put 3 different bulbs on it today, and kept getting the same problems, none of them were new, but to have 3 bad bulbs? Maybe the fuel pump since we had to keep squeezing the bulb to maintain power? Please give some advice guys, I just put this thing on and the last thing I want is to have to spend forever working on another engine. The boat did something very similar with my old 70hp recently, I figured it was the same bad bulb, but the 70 did not cut out completley like the 112.?????:confused2:
     
  2. Bubbakat

    Bubbakat New Member

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    4,532
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    McMinnvill
    Check the fuel lines all the way to the bottom of the tank. It is either sucking air or the fuel pump is bad. Take the line off the fuel pump on the outbound side and put a short piece of fuel linf from it into a jar or something you can see into and turn the engine over and see if that fuel pump is pumping. That engine is starving for fuel when it get to wot it uses more fuel then the pump is letting into the carbs.
     

  3. tbull

    tbull New Member

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    3,318
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    SW Ohio
    By sucking air do you mean there could be an air leak in the tank itself? I just put a new sending unit on, and 1 of the screws wouldnt tighten back down like it was stripped, do you think 1 screw being loose could cause that if it turns out the fuel pump is good?
     
  4. Bubbakat

    Bubbakat New Member

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    4,532
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    McMinnvill
    Naw that wouldn't affect it at all even if you pulled the whole sending unit out and left the whole open.
    When the fuel is picked up from the tank in the pick up tube it canot have a leak in between the pick up line in the tank and the carb or it will starve the engine for fuel. It runs off a vacum pulse and draws the fuel up every time the pump gets a pulse from the engine. If where the fuel line hooks to the tank has a check valve in it then take it out and put a straight barbed elbow in its place. Take the pick up tube out of the tank and make sure the little screen on the end hasn't collected a lot of trash on it. Make sure the pickup tube is in good shape if not then replace the pick up tube.
     
  5. tbull

    tbull New Member

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    3,318
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    Thanks bubbakat I will give all of that a shot, i will check the pump first, and then move on if needed. Will post back with what I find, thanks again.:wink:
     
  6. catfisherman_eky3

    catfisherman_eky3 New Member

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    Sounds like you will have ya a good boat
     
  7. tbull

    tbull New Member

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    3,318
    State:
    SW Ohio
    I pulled the pickup tube and valve, and it was all clear inside. So I tried the other test, I hooked up another fuel line from the outbound side of the fuel pump, and into a glass, I cranked it a few times and I did get some fuel in there, not a bunch but some. I did have to prime the bulb to get some in there, no I did not prime the buld until fuel poured into the glass. Something interesting is I found what I guess is a valve on the side of the boat, I wondered what that thing was, I unscrewed the plastic cap and smelled fuel, I was wondering where the relief valve was on this boat and I guess I found it, crazy question but could that have anything to do with the problem? I did notice a small crack in the line from the pickup tube to the tank, but I may have put in there when I was removing the hose, I clipped off about 3 inches of the hose to be safe since there was more than enough anyway....Again not alot of fuel in the glass, but a little bit...what now?
     
  8. Bubbakat

    Bubbakat New Member

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    4,532
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    If it won't create enough suction to pull the fuel from the tank you either have a place sucking air inbetween it and the tank or the pump diaphgram is bad. Take the line off from the inlet side of the pump and put you finger over the hose and pump it and see if it has good pressure againest your finger. I don't understand what the relief valve would be but I would take it out unless it runs it through a filter there.
     
  9. tbull

    tbull New Member

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    3,318
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    SW Ohio
    The relief valve runs from the opposite side of the tank, by that I mean the other end that doesnt have the pickup tube or fuel lines, its a seperate line that runs out to the side of the boat, and goes through to the outside kind of like a through hull pump would look like, and then on the outside of the boat is a cap that screws on and off, basically the cap keep the line from falling back into the boat. For the other test, are you wanting me to take off the line that would run from the tank to the fuel pump,at the fuel pump, and put my finger over that while pumping the bulb?
     
  10. tbull

    tbull New Member

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    3,318
    State:
    SW Ohio
    I did that also just now, and it feels like pretty good pressure, enough to make the gas shoot out pretty good if I move my finger to soon.....:smile2:, its still hard to gauge what it should feel like, the weirdest thing is that I had the same problem with the engine I just took off, that is what is really stumping me right now??:confused2:
     
  11. Bubbakat

    Bubbakat New Member

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    4,532
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    Borrow or beg someone to let you use a small portable fuel tank with a new or good short fuel connection and try that. What type of motor did you take off and why.
     
  12. jason454ci

    jason454ci Active Member

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    1,307
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    Zanesville, Ohi
    Just a thought here guys. It sounds to me what you are referring to as a relief valve Travis may be a vent. Is it possible Bubba if it is a vent and closed that it could be vapor locking or something?
     
  13. Bubbakat

    Bubbakat New Member

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    You are absolutely correct Jason
     
  14. tbull

    tbull New Member

    Messages:
    3,318
    State:
    SW Ohio
    I took off a 1989 70hp johnson, it was a great motor but I just wanted a little more speed, and my buddy gave me a great deal on the 112hp rude...I wish I could post pics on here of that valve for you guys to see, I thought of vapor lock also, but this valve is shapped so weird, if you can imagine a threaded cap, that has another cap inside of it, with a gap cut out in the middle of the inside cap, and a gap cut out on the outside cap, so it looks like the vapor can be released in the small space inbetween the inside and outside cap.......Man I know that sounds confusing...:confused2:...Here are the conclusions I have came to.

    1. The fuel pump did pump some fuel into the glass
    2.There was fairly good pressure on the fuel line when I pumped the bulb, and put my finger over the inbound fuel line.
    3. The pickup tube, and screen were clean
    4. This happened on the other engine as well

    I may have to try the seperate fuel tank, I wish I would have removed the fuel cap while on the water to see if it made a difference, or have noticed that valve on the side.