Best way to check for spark?

[Muppet]

Not sure of the best way to check for spark, 74 150 hp merc

 

[Muppet]

Re: Best way to check for spark?

nvm, used a test light and now I see I have no spark. Agh. Any idea what to check first?

 

[brehlers69]

Re: Best way to check for spark?

On a 74 you should have condensers and points under the fly wheel. I would start from the plug out. Go to the wire make sure its ok and connected properly and work your way in. your points may be under the fly wheel so you need a special tool to pull the fly wheel but you can get them cheap. I have a 68 and it didnt have points but a pulse pack and that wasnt cheap. If you get a book itll take you through checking all that.

 

[Motor Boater Bill]

Re: Best way to check for spark?

Might want to check a manual--I don't know for sure about 150's but by 1974 smaller Mercs were using CDI boxes instead of points. Might not need to pull that flywheel just yet. Have a look at your wires--mid-70's Mercs had a rep for bad wiring.

 

[Boatin Bob]

Re: Best way to check for spark?

I had a 76 150 and the darn wires actually had a threaded end that screwed into the dist, be careful and don't just go pulling the wires! Found out the hard $$ way not to do it. Here in Canada each wire cost me $18.

 

[OperativeK]

Re: Best way to check for spark?

Originally posted by Boatin Bob:<br /> I had a 76 150 and the darn wires actually had a threaded end that screwed into the dist, be careful and don't just go pulling the wires! Found out the hard $$ way not to do it. Here in Canada each wire cost me $18.

Me too, first boat, first Merc. 1971 1350.

 

[Muppet]

Re: Best way to check for spark?

ya it doesnt have points, I am trying to see if the coil is even sparking to the dist. Not sure how to check for that or what wires should be hot. I see the green wire going to the switch and the black going to ground. Currently I don't have a multi meter but will go pick one up soon.

 

[Motor Boater Bill]

Re: Best way to check for spark?

Not too sure about this but I have heard reference to a "Mercury switch" that kills the spark when the motor is tilted. If your motor has one of these, you might see about bypassing or disconnnecting it, also disconnect the kill switch, if either of these or the wires to them are shorting to ground that can result in a no-spark condition, and either of these is cheaper than replacing the CDI!

 

[Chris1956]

Re: Best way to check for spark?

Muppet, The mercury switch is on the port side of the switch box. It is a blue cylinder-shaped thing with a wire running to a connector on the switchbox. It is best to disconnect it.<br /><br />Now on the other side of the switchbox(starboard side of motor), the top red wire should have +12V all the time. The connector below it (white wire) should have +12V on it when the key is in the on (or run) position. If you disconnect the hightension lead from the coil (it just pulls out), and unscrew it from the center of the dist. cap, you can reinstall it into the coil, crank the motor and check for spark.