Attn Old Motor Experts... 56' 7.5 Evinrude

Discussion in 'Boats and Motors' started by BrianSipe17, Oct 10, 2007.

  1. BrianSipe17

    BrianSipe17 Brilliant!

    I bought an old Evinrude 7.5 Fleetwin this summer and am just now getting around to working on it. The motor looks unbelieveable... almost like new and super clean. When I got it started in a garbage can, it is clear to see oil is coming from exhaust. Actually, I think it was unburnt gas because it smells like gas. I started it with each cylinder (unplugged one coil each time) and both are working. I originally thought maybe one cyl. wasn't firing. I am still getting the gas/oil from the exhaust.

    Also, while it starts, it will not idle and it seems to have very little power. Any thoughts???
  2. 2 strokes always have gas/oil in exhaust. That's the problem that EPA's have with that type motor. You'll always get peanut butter looking residue, especially when run in a closed container like a trash can. Out on the water it leaves a rainbow trail behind boat. Just my 2 cents.

  3. BrianSipe17

    BrianSipe17 Brilliant!

    Thanks Fisherball. I think there is more to it, since the motor is not running well, though.
  4. Fisherball is right that you can probably expect some in the exhaust, particularly from a motor as old as that one. But what you described sounds like it is probably more than it should be. I would first suggest a good cleaning of the carburetor and fresh plugs if you have not already done so. The lack of power and not idling could both be due to the dirty carb as well. I don't really know enough about maintenance on them to suggest anything else at this point but I would try those things and focus on getting it to run properly. Once that is accomplished you can further address the unspent fuel in the exhaust issue if it is still present.
  5. Lewis


    Both cylinders could be firing but the spark could be weak.
    Pull the flywheel and clean,replace and re-gap the points.
    No corrosion and proper point gap is critical on these engines.
    It is part of a standard tuneup.
    Also inspect the coils for cracks.
    Cracked coils are very common on these older motors.

    Parts are available at NAPA.
  6. BrianSipe17

    BrianSipe17 Brilliant!

    Thanks Lewis. I believe the points are newer, but the gaps were off a little. The spark is weak. I checked the plugs by pulling them out an pulling the flywheel. It has one new coil, but I am buying another to replace the other one. THanks for the info.
  7. BrianSipe17

    BrianSipe17 Brilliant!

    Good news, Jigtwins and I took the flywheel off and checked the wires. One was not good and replaced it. We also regapped the points. It immediately ran better. It is still bogged down a little. However, it does idle much better.

    I think I will remove the carb and clean it and the reed valve. The needle valves seem to need a little adjustment, too. Does anyone have any other thoughts? I still think it is getting an insufficient fuel/air mix.

    Also, and most importantly... the old motor manual calls for a 16:1 mix, using SAE 30. What mix is best for use with 2 cycle outboard oil? I would presume 24:1 or 32:1 would be sufficient.
  8. Brian,
    I would call 419-734-2224 and speak to Mark or Lee. They forgot more about OMC outboards than I'll ever know. Talking with them recently they explained they have seen a lot of problems with the older outboards that are all fuel related,i.e: new fuels eating old rubber and such in the old fuel systems.

    It was explained to me that a new gasket set and rubber parts for fuel pump that are impervious to the caustic nature of the newer fuel blends will cure
    95% of your problems with idle and such, and only cost in the $20 range.

    I am sure they could lead you to the right parts and such. Just my thoughts. They are good folks.

  9. BrianSipe17

    BrianSipe17 Brilliant!

    Well, took off the carb, cleaned reed valves, and got the needles dialed in. It is screaming now!