Here is a good ignition problem...

Thumbtack

Petty Officer 2nd Class
Joined
Aug 3, 2007
Messages
118
Mercruiser inline 4cyl. 3.7L conventional Ignition.

For some reason I only have spark coming out of one post from the distributor cap. Originally I had no spark, then I did a tune up (cap, rotor, points, condensor). Now after doing that I have spark but only out of one post from the cap. I'm going straight from the cap posts to my spark tester to an engine ground, I'm not using any plug wires or spark plugs for this test. For some reason the book tells me a different dwell measurement than what is written on the engine but I tried the dwell in both positions but got the same problem. I am out of ideas as to why spark would come out of one post but none of the others. Any one have any ideas? Could I just have gotten a bad cap?
 

rbh

Fleet Admiral
Joined
Mar 21, 2009
Messages
7,939
Re: Here is a good ignition problem...

take the cap off and bar over the engine, is the points opening and closing when they are supposed to?
your points could be hanging up
rob
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: Here is a good ignition problem...

Worn bushings in the distributor will do it, loose rotor, cap not on square.
 

Thumbtack

Petty Officer 2nd Class
Joined
Aug 3, 2007
Messages
118
Re: Here is a good ignition problem...

The points seemed to be opening and closing ok, I was looking at them most of the time as I was checking the dwell. I'll try to make sure the cap is on square because chances are it was something that I did.
Thanks
 

Thumbtack

Petty Officer 2nd Class
Joined
Aug 3, 2007
Messages
118
Re: Here is a good ignition problem...

The cap and the rotor both seem ok so I guess I'll take a look at the bushings in the distributor and go from there.
 
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