79 Mercruiser-120 No spark

Will Brad

Recruit
Joined
Apr 2, 2008
Messages
5
Changed coil, points, condensor. Put in new plugs. Has power to coil. Won't start. Started before. Removed engine, changed freeze plug. Put in new plugs. Still nothing. It just cranks. Looking for a different wiring diag. then the one in seloc?
 

uaw9fan

Petty Officer 2nd Class
Joined
Oct 25, 2005
Messages
112
Re: 79 Mercruiser-120 No spark

Have you disconnected the shift interrupt switch to verify there is no problem in that area.
 
Last edited:

chiefalen

Captain
Joined
May 18, 2008
Messages
3,598
Re: 79 Mercruiser-120 No spark

You pulled a plug and cranked it while grounding the plug no spark?

If yes, points to wide?

Condenser could be bad from brand new.

Wires clean all around, grounds also.

Dizzy cap clean inside good connection of rotor.

Plug wires good, one from coil to dizzy good?
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
71,082
Re: 79 Mercruiser-120 No spark

Changed coil, points, condensor.

Ayuh,....

Did you properly Set the Points,..??
Did you set the Dwell,..??
Did you reset the Timing,..??
Is there power to the hot side of the Points,..??
 

Will Brad

Recruit
Joined
Apr 2, 2008
Messages
5
Re: 79 Mercruiser-120 No spark

To all the people who gave suggestions, finally deciced to purchase a new starter, (stopped cranking). Installed starter and what do you know, it started right up. Thanks for all the help.
:rolleyes:
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: 79 Mercruiser-120 No spark

Obviously, it was cranking so slow with that bad starter that it wouldn't start.
You do have to get enough rpm while cranking for the engine to actually start and run.
 

chiefalen

Captain
Joined
May 18, 2008
Messages
3,598
Re: 79 Mercruiser-120 No spark

Stupid me and i thought he had no spark. I didn't see nothing about a slow cranking starter.
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
71,082
Re: 79 Mercruiser-120 No spark

Stupid me and i thought he had no spark.

Ayuh,...

He never said he did,... Only power To the coil....
 

Bt Doctur

Supreme Mariner
Joined
Aug 29, 2004
Messages
19,344
Re: 79 Mercruiser-120 No spark

If the solenoid supplies power during cranking ,I guess it could short out and provide no power for spark
 
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