No spark Mercury 850

[IronOutlaw]

I bought a boat today with a late 70s mercury 850. Prior owner says he was riding across the lake and it just shut off and he never has gotten it to crank back.

The wiring seems to be a mess with a the power tilt and trim, livewells, bilge pumps, etc but the harness from the engine looks good except he tried to wire up a new ignition switch that still doesnt work.

My first question is does the ignition switch provide a current for the spark? Im gonna get a new switch and try.

What other sensors or devices can cause a shut down like this? I ruled out coil packs because I doubt all would go bad at the same time. I have a Clymer Shop manual Im reading but it seems very bland in the troubleshooting area.

I know there is a stator and crank sensor under the flywheel. Can these just randomly go bad all at once and cause no spark?

I work on cars alot but boats are a little different and Im learning so bare with me on my newbie questions. Is there any way I can test each part of the ignition system and check what is good and what is not?

Enough rambling for now,

Trent

 

[Laddies]

Re: No spark Mercury 850

Is it battery ign with a distributer or ADI 4 coils?

 

[IronOutlaw]

Re: No spark Mercury 850

Its got the four coils, four cylinder motor. Tomorrow Im gonna go buy a new switch and wire it up and see if I can get power to anything. Last owner tried to wire up a switch but had it wrong.

No coil is giving spark to the plugs. I really hope its nothing to do with the stator or trigger under the flywheel.

Does anyone know where to find the mercury tilt switch that cuts off power when the motor is tilted, (if it has one). Im wondering if it got broke somehow and isnt letting anything get power.

Only way Ive gotten the motor to turn over is by shorting out thet cylinoid. The starter is good and the motor feels like its got good compression, and its getting gas, I just need spark.

 

[Chris1956]

Re: No spark Mercury 850

There is a troubleshooting guide for that motor on the CDI Electronics web site.

The tilt safety switch, if it has one, will be connected to the switchbox's orange wire.

 

[Laddies]

Re: No spark Mercury 850

Do not hook 12 volts to the system as it will destroy it, here's a test for it.

 

[IronOutlaw]

Re: No spark Mercury 850

Do not hook 12 volts to the system as it will destroy it, here's a test for it.

Can you please elaborate, do you mean not to use a 12 volt battery?
I used my car battery to test the starter yesterday.

Can I use a car switch from autozone for an ignition switch or is it mandantory to use a $20 mercury switch?

 

[Chris1956]

Re: No spark Mercury 850

Your Alternator driven ignition (ADI) does not use battery voltage to generate spark. You neen a magneto-type ignition switch. I do not know if Autozone carries them, but you will want a marine grade one. If you want one to fit the MerControl, a dealer is the best place.