Your Best Technique for Rope Starting Merc 20hp EFI

[SeaKaye12]

Well....I have a "new to me" 2020 Mercury 20hp EFI that runs 100% but challenging to start. It's not electric start.
If I use a drill it starts immediately.....and it seems to start better if I run the drill slowly. Interesting.

That leads me to think that I should apply the same technique to rope-starting. Long (full rope length) slower pulls. Sometimes works.

Those of you who have these engines.....share your starting secrets? Please? Thanks!

 

[airshot]

Carry a cordless drill with you if rope starting is not an option. I have saw guys make mods to there cover so the hood does not need to be removed to use a drill. More noise when running with a hole in the hood though.

 

[boscoe99]

Running a drill motor, or pulling a start cord, more slowly is counter intuitive to my thinking.

Pull the cord more slowly and let us know what the result is please.

 

[SeaKaye12]

Boscoe; I would certainly agree. Every other motor I've ever had liked to be pulled hard and fast. The harder and faster the better! Get that fuel sucked up where it needed to be.

These four strokes though have a compression release of some sort. I can tell when I spin the drill. At lower RPM there is a different feel. Get the RPM's up a bit and all of a sudden I can feel the compression kick in. Maybe that has something to do with it?

I also find that, contrary to the Owners' manual.....it helps alot if I give it some throttle. Twist the grip to maybe quarter throttle. The manual states that it should be at the fully closed position.

I'm slowly getting a technique that works. I posted to see what other owners of these motors have to say. There is certainly no shortage of forum posts saying that these EFI Tohatsu/Mercuries are hard to start. Of course there is no choke or enrichener. The carbureted versions had one or the other....and the use of that typically would also bump the throttle open a bit in the process.

 

[boscoe99]

I agree that motors can be like living animals. Each having their own preferences as to how they like to wake up.

Since your model does not use a battery it relies upon the alternator to generate the electrical power needed by the ECU and the electric fuel pump. Permanent magnet alternators typically create more electrical power the faster the magnets wiz by the stator coils. Which is why the motor starting easier with slower rotation is confusing me. But I am old and get easily confused these days.

 

[Texasmark]

Carry a cordless drill with you if rope starting is not an option. I have saw guys make mods to there cover so the hood does not need to be removed to use a drill. More noise when running with a hole in the hood though.

Most sparked outboard engines use a rotating magnet on the flywheel passing an iron core coil of wire, anchored adjacent to the flywheel magnet to generate the trigger voltage to cause the spark plugs to fire.

The equation for how that works is V (output voltage amplitude) = [ L (inductance of the coil) x di (actual current change) / dt (period of the change)]. Simplified: V= L di/dt.
Therefore the faster the magnet passes the coil (minimizing the time), the higher the di/dt number x the constant (L) increases the induced voltage output. You are correct in that pulling slowly generates less voltage for spark generation.

Multitude of decades ago, I had a new rig with a Chrysler 85 HP 3 cyl. 2 stroke. I only had one battery and in operating my trolling motor...new rig, first trolling motor, had to learn the ropes.....I ran the battery down. The cover over the engine had a plastic patch on the underside and in the pouch was a cranking rope. I set the controls like I was going to start the engine with the key in the normal manner with the key in the ON position. Put the rope around the slot on top of the flywheel, got in what I thought was a good solid position and pulled as hard as I could.....engine fired right up, first pull, which was easier on me than I thought it would be with an 85 HP engine.
Obviously the moral of that story is to have 2 batteries which I had the next time I went fishing and no more cranking rope starts.