1956 Evinrude 15hp Throttle Q and Fouling

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  • andreaskc


    Replies: 5
    Topics: 1
    #239679

    Two questions here as referenced in the topic title, but will give a short known history of outboard….

    I picked up a 1956 Evinrude 15hp late last October 2020. History is a bit thin on outboard, but looks to have always been a Missouri motor with an antique metal Missouri license plate affixed to the power head. We have put it on a 12 ft tunnel hull Livingston with fun success. It was supposed to be tuned up by a mechanic in Booneville, MO β€œallegedly”. It had a hacked fuel pump addition from the front reed area that wasn’t enough to run at high speed for long? I replaced it with a pump that attaches to bypass and fuels nicely now. Compression on both cylinders in mid 90s. Running Champion J6c plugs. Using Lucas blended synthetic marine oil at 24:1 and 91 octane gas w no ethanol. I have also adjusted high/idle screws to run appropriately on this mix.

    After 3 straight weeks of wringing the heck out of this little outboard and last full day of our vacation, I was a bit short on Lucas oil and picked up a random marina 8oz two stroke bottle mixed with a little bit of Lucas to do 32:1 on 5 gallons. We used 3 gallons of this and then ended up fouling the bottom spark plug. Replaced with a new plug, ran great again for a few mins and went back to one cylinder. Fired up fine the next morning to load up on trailer. Came home and pulled plugs, bottom newer plug looks maybe more oily but tip is dry. Holding plug against bolt and pulling starter rope makes a nice blue spark on both wires. Did I mess something up with the oil mix or that unrelated?

    Different question, on the throttle twisted as far as it will twist it looks like there is still and inch or so left on the timing plate that pushes the carb throttle open and a fingers worth of additional movement that could be had on the throttle opening. Does this sound like correct positioning? Attached photo of additional play on the cam roller.

    785A26CD-5811-4518-AD4A-920D46B6BC5B

    • This topic was modified 5 days, 19 hours ago by Mumbles.
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    crosbyman

    Canada Member - 2 Years
    Replies: 2121
    Topics: 227
    #239681

    stuff to read see parts 1-6 at the bottom reviving a 1956 15hp πŸ™‚

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    crosbyman

    Canada Member - 2 Years
    Replies: 2121
    Topics: 227
    #239682

    throttle START ====> Roller on the notch mark on the cam cam can be unbolted and dragged forward to just touch the roller

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    andreaskc


    Replies: 5
    Topics: 1
    #239686

    Thanks, missing the little label on the throttle that says β€œstart”… is there another way to ascertain that? I see notch on the cam plate


    fleetwin

    US Member - 2 Years
    Replies: 3829
    Topics: 39
    #239715

    Well, just because it sparks when you check with the plugs removed, does not ensure you have good strong spark while running under compression…Try those inline neon testers while running when it starts to mess up….Have you had a look at the coils? Old coils tend to crack, you can have a quick look pretty easily by removing the recoil and the little inspection plate on top of the flywheel…I just reread your post, where you indicate the engine had a recent “tune up”. Perhaps they messed up the ignition. You swapped the fuel pump back to the bypass cover, and plugged the intake manifold port. Does it look like someone had the intake manifold off? Perhaps your fuel pump is leaking past the diaphragm into the cylinder, but am guessing the fuel pump is mounted on the top cylinder.
    The only other thing that comes to mind is that this era of 15hps used a regular lower seal instead of the usual carbon seal set up…The regular seals tend to rust up and come apart over time…Needless to say, there is no way of inspecting without pulling the powerhead, which I don’t want you to do until all other possibilities have been exhausted. The only other thing that might indicate a bad lower seal is the presence of water on the plug(s).


    andreaskc


    Replies: 5
    Topics: 1
    #239739

    Thanks, haven’t seen one of those neon testers before and I’ll pick one up. I’ll take the recoil off tonight and have a look, I’m curious if the “tune-up” or any “tune-up” ever replaced the coils. We ran about 30 gallons of gas thru the motor in 3 weeks of vacation, so it was working pretty darn well… until half-way thru the last batch of different gas mix (see original post)… wasn’t sure if it was coincidence or not.

    Fuel pump is in the top bypass, intake looks like it hasn’t been removed in decades. I suspect the recent tune-up was a carb clean, plugs, some rickety fuel pump change and lower unit gear oil.

    I did order a few J8C plugs to try? Also wondering if I should try decarbing the engine. Going back to the lake in two weeks and trying to button up any issues so we can fish the heck out of this boat again.


    fleetwin

    US Member - 2 Years
    Replies: 3829
    Topics: 39
    #239741

    I would not use the J8C plugs, unless you plan on idling all day long, they are a bit too hot for high speed running. I’m sure the boatyard replaced the coils if they were cracked, kind of hard to miss that. But, they may have misrouted ignition leads under the flywheel, which may have eventually rubbed through….
    The fuel pump is on the top bypass, so an issue there would be affecting the top cylinder….You mention that the intake looks untouched, so I guess issues there are not likely. What about the fuel pump pressure port that comes off the intake, is it plugged off securely? You could try decarbonizing, but that is probably not an issue unless you have been idling/trolling excessively.
    Again, any evidence of water on the plug(s)?
    I’m not sure about whatever lucas oil blend you are using, you mentioned using some generic stuff also, perhaps that is an issue.
    Finally, this is a relatively low compression engine, there is probably no benefit from using the higher octane fuel…But, I realize you are using it mostly due to the lack of ethanol.
    Finally, how does the engine run before the lower plug gets fouled? Idle OK?

    • This reply was modified 5 days, 23 hours ago by fleetwin.

    crosbyman

    Canada Member - 2 Years
    Replies: 2121
    Topics: 227
    #239761

    see bleeder 2-1 initial file was wrong…

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    • This reply was modified 5 days, 12 hours ago by crosbyman.
    • This reply was modified 5 days, 12 hours ago by crosbyman.
    • This reply was modified 5 days, 12 hours ago by crosbyman.
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    fleetwin

    US Member - 2 Years
    Replies: 3829
    Topics: 39
    #239770

    see bleeder 2-1 initial file was wrong…

    • This reply was modified 5 days, 12 hours ago by crosbyman.
    • This reply was modified 5 days, 12 hours ago by crosbyman.
    • This reply was modified 5 days, 12 hours ago by crosbyman.

    Good point, forgot about the drain system…..


    crosbyman

    Canada Member - 2 Years
    Replies: 2121
    Topics: 227
    #239774

    in the coming weeks I’ll be checking out my friend’s fouling… 5.5 and will clean out the bleeder circuit if only for peace of mind…and will report back asa Ican .

    a shot carb cleaner small wire and 90 psi should see to fixing any blockage. πŸ™‚

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    andreaskc


    Replies: 5
    Topics: 1
    #239857

    Finally coaxed the flywheel inspection bolts off without stripping them tonight. Few initial findings…..

    Coils not cracked
    Coil/Points/Condensers all look very clean/shiny

    One of the coils still has a fabric coated wire connected to the points and looks slightly frail at the coil connection. The other coil has a nice heatshrunk plastic coated wire with modern writing on it.

    Observing the spark plug wires as they move when throttle is advanced to wide open shows that both wires, but especially the bottom cylinder wire is chafing against an exterior metal support and has made a significant dent into the plug wire…. not enough to show internal wire, but looks problematic.

    I think my plan is now to pull the flywheel, replace the solo fabric sheathed wire from coil to point and run new plug wires trying to avoid them from making physical contact with metal frame as they are advanced.

    Attachments:

    andreaskc


    Replies: 5
    Topics: 1
    #239862

    Other commentary…. I think I now understand how the cam roller works with the throttle. I don’t have a indicator band on the handle so hard to know “where” start is supposed to be, but I did look thru a book I bought of “cheap outboards” which has a good diagram/explanation of this…. currently by the time the roller hits the indicator the throttle plate inside the carb has already moved a bit, and not the book explanation of that the roller should be at indicator when the slack in the linkage just starts to turn the carb plate open.

    So, sounds like the carb is opening a little sooner than expected at the indicator, any ideas how this would make the motor behave at this timing? Would adjusting it back some make it idle even better?

    • This reply was modified 4 days, 19 hours ago by andreaskc.

    crosbyman

    Canada Member - 2 Years
    Replies: 2121
    Topics: 227
    #239868

    you can always try to set the carb control arm / roller at different locations by unscrewing the bolt under the fw….do some testing

    as to electricals…why not go all the way for peace of mind 10 miles out. Chineese coils are cheap a few feet of metallic 7mm & boots will solve any problem with old wires/coils

    https://www.ebay.ca/itm/1-5-40HP-Outboard-Engines-Ignition-Coil-For-OMC-Johnson-Evinrude-584477-582995-/203247943567?hash=item2f52857f8f

    Belden 7mm metallic ignition kits for old cars work great , not expensive per wire & boots are factory assembled πŸ™‚

    Joining AOMCI has priviledges πŸ™‚

    • This reply was modified 4 days, 12 hours ago by crosbyman.
    • This reply was modified 4 days, 12 hours ago by crosbyman.
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    fleetwin

    US Member - 2 Years
    Replies: 3829
    Topics: 39
    #239920

    It is kind of hard to avoid having the plug wires rub/jam on that bracket at WOT, just the way it was designed….The minor wear shown in your pictures does not look like an issue and would most likely affect the engine at that WOT position before slow speeds. I don’t really understand your description what you are seeing under the flywheel inspection plate, perhaps just one coil was replaced, older coil primary leads had the fabric cover wire you mentioned. Did both coils look identical?
    I don’t want you to rip this ignition system apart needlessly, you really need the OMC puller to get the flywheel off, something I’m assuming you don’t have. I guess my next step would be to use the neon inline testers to see if the lower plug is actually fouling, or if you are losing spark to the lower cylinder. It is best to do this testing during sunset or sun up so the neon testers are easier to see…


    fleetwin

    US Member - 2 Years
    Replies: 3829
    Topics: 39
    #239921

    Other commentary…. I think I now understand how the cam roller works with the throttle. I don’t have a indicator band on the handle so hard to know “where” start is supposed to be, but I did look thru a book I bought of “cheap outboards” which has a good diagram/explanation of this…. currently by the time the roller hits the indicator the throttle plate inside the carb has already moved a bit, and not the book explanation of that the roller should be at indicator when the slack in the linkage just starts to turn the carb plate open.

    So, sounds like the carb is opening a little sooner than expected at the indicator, any ideas how this would make the motor behave at this timing? Would adjusting it back some make it idle even better?

    • This reply was modified 4 days, 19 hours ago by andreaskc.

    Again, not sure I understand what you are describing here. Cam roller pick up adjustment is not necessarily the “start position”. The carb butterfly should just begin to start opening when the line on the throttle cam bisects the rubber cam roller. This adjustment can be tricky due to all the slop in the carb throttle linkage. In other words, the linkage rods might start moving at this point, but that doesn’t mean the butterfly shaft is actually starting to open due to the somewhat normal “slop” in that linkage…
    The engine will run a bit lean off idle and bog on acceleration if the carb butterfly shaft starts to open before the mark bisects the roller
    The engine will run a bit rich off idle and may stutter on acceleration if the carb butterfly starts to open after the mark bisects the roller.
    Again, this adjustment is to synchronize the carburetor and ignition system and has nothing to do with the start position on the tiller twist grip. The engine can be started either above or below this position.

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