Motor not sparking

supermanDan

Recruit
Joined
Feb 5, 2008
Messages
1
Hey everyone,
I have a 1984 Mercury 25 HP motor....I know, I know....I need a new one.....right now that's just not an option for me.

Anyway here's my problem:
the motor has set for about 4 months because i needed a new prop. I finally got the new prop and installed it last weekend and went to try her out. I had a feeling it might not want to run, so i got some fresh gas and mixture and tried to crank it in the yard with a hose flush. At first, the motor actually turned over (on choke) and after that....nothing. I happened to have anohter set of plugs (not new, but in better shape then the current ones), so i changed those out. After doing that, the motor cranked right up. i let it idle for about 25 mins, ocassionally revving it up a few times. I even shut it off and cranked it back up a couple of times without any problems. Then i hooked it up to my truck and ran down to the lake to try it out. Got the boat in the water and attempted to crank it (without choking it...since it had just been running about 15 minutes ago).....nothing. Then i choked it and it turned over. Took it off choke and could not get it to turn over again. I have since bought another set of plugs and the motor just will not turn over. I have cleaned the carb and I don't think that is my problem. So i moved my attention to spark. From what i can tell, i'm not getting any spark....not sure how this could have happened, but it did. I have a digital volt meter, but I'm pretty clueless on how to even use it, nontheless what to test. Can anyone give me any suggestions on what my problem might be or how to dianose this? Thanks in advance.
 

hkeiner

Lieutenant Junior Grade
Joined
Oct 17, 2006
Messages
1,055
Re: Motor not sparking

The below linked troubleshooting guide may be of help to you. While a multi-meter can be used to perform some bench tests, a DVA meter is needed for other tests. As a general opinon, I have found that it is cheaper in the long run to invest in a DVA meter to perform systematic troubleshooting tests (to identify the failed component) to minimize the likelihood of unnecessarily replacing expensive good components on a failed hunch or educated guess.

Having said that, there are some effective troubleshooting steps that can be done by swapping around ignition parts to see what happens to the spark and then deducing what ignition part is bad. Do a search on this forum for more information on that.

Good luck

http://dolphinmarineservice.homestead.com/ign5.html
 
Top