120 Mercruiser, no spark

[Valv]

I just bought this used boat, hasn't been run since 2005. 1974 Mercruiser 120hp motor oil is very clean, I assume it has been winterized and never used then.
Motor cranks fine but I have no spark.
-I disconnected dist. center post, grounded it, and no spark at crank.
-I opened dist, points close by specs
-When ignition is on if I open points with a screwdriver they spark.
-Coil has 12v power at + post and 12v power at - post.

Any other possible issue ?

There is an external condenser which is disconnected and wire is hanging loose, where does it go on the coil ?

Thanks for any help

 

[freddyray21]

Re: 120 Mercruiser, no spark

The condenser should not be an external one. It should be under the cap with the points. The condenser hooks to the same wire as the points. Then that wire goes up to the coil. If points sit for a while they tend to get glazed over. I would slip a piece of 220 grit sand paper between them and rub it back and forth to get any glazing off of them. Then reset them.

 

[vega74]

Re: 120 Mercruiser, no spark

same problem, same year, same scenario, replaced the points and condencer,cap,rotor, coil, plugs and wires and im still not getting a spark from the coil?.

 

[rbh]

Re: 120 Mercruiser, no spark

you know this may sound like a dumb question BUT when you crank over motor can you see the distributor shaft turn? (if no maybe a striped out shaft or the pin at the base gear sheared or gone), and if you can is the base plate loose and or coroded (bad ground)
do you hear any popping (snap) is the spark going to ground.
my two bits worth
rob

 

[Kovah55]

Re: 120 Mercruiser, no spark

The posts in the Adults only section are excellent, why not read them and go down the list to troubleshoot the problem, throwing parts at it, won't solve the problem.

 

[vega74]

Re: 120 Mercruiser, no spark

yeah, dist turns fine no popping or sparking or signs of a short anywhere, points set to spec, sill no clue

 

[schmitty04]

Re: 120 Mercruiser, no spark

I'm having a similar problem with an 83' - 120, any one have any experience with the shift interrupt causing interference with start up?

 

[APPALOOSA2]

Re: 120 Mercruiser, no spark

Have you pulled a plug and checked for spark at the plug ?

Are you sure its getting gas ? Fresh gas ?

Put a teaspoon of gas in the carb and see if it fires.

Carb might be plugged and have to be taken off and cleaned and rebuilt.

Sitting for 4 years I bet that carb is plugged.

 

[APPALOOSA2]

Re: 120 Mercruiser, no spark

same problem, same year, same scenario, replaced the points and condencer,cap,rotor, coil, plugs and wires and im still not getting a spark from the coil?.

You should start another post.

Do you have power to the coil ?

 

[Bt Doctur]

Re: 120 Mercruiser, no spark

The Basic method for points/coil system
Remove all the wires except the black one going to the dist.
Using a meter or lighted test probe, turn ign to "run" check for voltage at the + side of the coil.
Power but still no spark
remove black wire from coil , attach ohm meter to black wire and a good ground, spin motor, meter should show pulses,this means the points are opening and closing . No meter reading means the points are not opening and closing or the contacts are "glazed over" or the points assembly is somehow grounding itself out.
If the coil is known to be good, the + power is there, the points are set correctly and working (pulsing) ,the ign system will produce spark.
Once you have it running, reattach the wires you removed to see if it will stay running. Grey wire kills engine= bad/shorted tach