Mecrcury 9.9 HP shifting issues

[dougd1]

I am new to this forum and new to boating as well. I have picked up a second hand Mercury 9.9 HP outboard motor. Took it for it's first drive today and had some issues with it. Once started, it tends to rev high, and when shifting into forward, it slams into gear. Once in forward, it is impossible to shift back into neutral. I don't think I ever got into reverse with it. I have to kill the engine because I can't get it back into neutral.
Have also noticed it seems to have a prop that may be different from that listed in the Mercury parts list for this type of engine. My prop is stamped with 8.9 x 7.5, while the parts lists seems to use a prop 8.9 x 8.3. I also do not have a trim tab on the motor, but I don't think this is a particularly important. Am most concerned with the inability to shift into neutral? Any suggestions as to what could be wrong?
Thanks.
Doug

 

[JDusza]

What's your serial number?
Sounds like the first thing is to get the revs down. Stop the gear slamming. I think once this happens you'll be able to shift forward to reverse. Do you have a barrel you can drop the engine in? You can work it on the boat but it may be easier on an engine stand, moving your way around or recovering dropped tools/parts ...
To achieve idle, 2 fuel delivery attributes, idle speed and idle mixture, need to be adjusted perhaps with a small tweak to timing advance (depending on how low you want to idle). Sounds like you're dealing with a dirty carburetor that's been adjusted out of range in order to keep running. The low speed circuit in the carburetor is probably gummed up.
First off, note the position of your idle mixture adjustment by turning the adjustment screw clockwise until it stops, counting the number of turns it takes to close. Note this and reopen to initial position. Next, try adjusting the idle speed down and see if you achieve results without stalling.
As you adjust the speed down, simultaneously keep the engine running by adjusting the idle mixture screw, clockwise to close off fuel and run leaner, counterclockwise to increase fuel and run richer. If you adjust too lean, the engine will stall, just die. Adjust too rich and the engine will foul and cough just before stalling. Find the sweet spot with idle mixture that gives you the highest smooth revs. As the idle smooths out and increases, bring it back down with the idle speed adjustment. Once happy, back out the idle mixture screw another quarter turn to insure fuel delivery for quick acceleration. If you cannot achieve running at idle you may have blocked low speed jets in the carburetor. If you get totally lost in the adjustments, close the idle mixture screw all the way and back it out 1 1/2 turns. This should get you into a range where the engine should run. Then you can optimize the adjustments.
Propeller shouldn't be an issue unless it's slipping on the hub. 8.9 is the pitch and 8.3 is the diameter. Your replacement prop has the same pitch but is 0.8 inches smaller in diameter (0.4 inch radially). If it's slipping you'll get high revs and won't go anywhere.
J

 

[dougd1]

Serial number is OR126144, model number IF1020FK, year 2006. Guy I purchased the motor from was a small engine mechanic who claimed he had just adjusted the idle speed, changed plugs, oil, and gear oil. I don't have a barrel, but will look into getting one. Have contacted Mercury for an owner's manual, awaiting their response and will look at youtube for these idle mixture and idle speed adjustment needle locales. If the idle speed circuit is gummed up, what is the remedy to clear the low speed jets?
Did discover that there was no cotter pin in the prop nut. After my first run, the prop nut was only finger tight.
Thanks for getting back to me.
Doug

 

[JDusza]

A good carburetor cleaning with spray cleaner and a small diameter wire (florist wire) to reem the jets. Maybe compressed air to further clean and dry the parts. There are a couple places to clean out.
First is the idle mixture adjustment needle and seat. Remove the needle, inspect for tip damage and dirt. Spray both needle and seat with cleaner and gingerly poke a small diameter wire through the seat to be sure it is clear. A small proxy brush may be successful but you need to be sure you do not scar the seat. Pull the top cover from the carburetor adjacent to the needle seat and be sure pathways are clean
Second is the low speed jets. They are inside the carburetor throat and are exposed as the throttle butterfly is opened. You will see three or four small holes in the side of the carburetor throat as you articulate the butterfly. Reem these with cleaner and wire as well. Be sure not to scar the holes.
Lots of YouTube videos out there. Recommend watching a couple.
J

 

[dougd1]

Thanks again for getting back to me. One thing I am not clear on is why the idle speed settings affect shifting back into neutral from ahead. I can see why the slamming occurs when going from neutral into ahead because the engine is revving too high, but I cannot get back into neutral from ahead, in spite of applying a lot of force on the throttle handle.
Doug

 

[flyingscott]

Because there is to much force in the lower unit, that is why you cant shift. If this is a Mercury built motor I would stop shifting until you fix the idle. Those lower units are not strong and expensive to replace. If your motor has the knob for the primer see if it turns to the left. That knob can set your idle for cold starts and if is not turned down the idle stays high.

 

[dougd1]

Because there is to much force in the lower unit, that is why you cant shift. If this is a Mercury built motor I would stop shifting until you fix the idle. Those lower units are not strong and expensive to replace. If your motor has the knob for the primer see if it turns to the left. That knob can set your idle for cold starts and if is not turned down the idle stays high.

As it turns out, I found two loose bolts under the shifting mechanism inside the engine cowling. One night I was playing with the shifter without the engine runnning - all was well, and then moved the engine. Next morning, it would not shift at all, which made me look a little closer. That's when I found the two loose bolts. I think those were the primary culprits in my issue. I then adjusted the idle speed down just a tad, to reduce the hunting of the engine when at idle. Am taking it out tomorrow morning for another run. Will see what happens.