mercruiser has no spark

smarc

Cadet
Joined
May 22, 2012
Messages
8
just bought an older boat with a 140 hp mercruiser the motor turns over great but i have no spark i changed out the coil and tested it with a test light and both sides of the coil light up, also changed out the points, and yet still no spark.

is there something i m missing i have two wires running to the coil and one from the distributor to the coil

i dont know much about points. just hoping someone can help
 

smarc

Cadet
Joined
May 22, 2012
Messages
8
Re: mercruiser has no spark

i have changed the points and still nothing, does anyone know where i can get a wiring diagram the motor i was told it is a 1985 but not to sure on the year
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: mercruiser has no spark

Did you look at that link I posted?
 

smarc

Cadet
Joined
May 22, 2012
Messages
8
Re: mercruiser has no spark

i looked at the post and i will try and test the coil i have another coil off a parts motor i bought but not to sure because it was saying there is a purple wire on the coil and all i have is two brown wires and a yellow going to the coil and a black one coming from the distruibtor i dont know if i bought someone eles mess but it is staring to seem so
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: mercruiser has no spark

You must have a lot older engine than boat. Look just above and aft of the starter and see if there is a serial number tag riveted to the block.

3.jpg
 

smarc

Cadet
Joined
May 22, 2012
Messages
8
Re: mercruiser has no spark

i will check thanks for all the help i hope i can figure something out
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: mercruiser has no spark

Let's try some testing.
Take all the wires off the coil except the one going from the - terminal of the coil to the distributor.
With a jumper wire, go from the battery positive terminal to the + terminal of the coil and see if you have spark.
Remove your jumper wire.
 

smarc

Cadet
Joined
May 22, 2012
Messages
8
Re: mercruiser has no spark

hey thanks Don S for all you help boat started little bit rough but now the fine tuning will start, i was reading on the engin and the parts engin i have the coil on the parts engin had no internal resister, and the coil i had original had the internal resister, took a bit of research but finaly with your help and the help of the site i got it running thanks again
 
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