Weak spark new components

[bennysku]

OK, I've been fighting this issue for awhile now. When I remove the spark plugs I get spark (not always consistent). With spark plugs in I get no spark. I bought a new stator, rectifier, and power pack. Minus the key switch and timerbase/sensor coils that should make up the ignition. Key switch and sensors must be working if I get spark w/o plugs. While cranking I get 300rpms. Got a service manual and all test readings are good.

Any ideas or thoughts would be appreciated. I'm not sure where to go from here.........

 

[bennysku]

Re: Weak spark new components

This is on a 1977 Evinrude 140hp.

My issue sounds very similar to post:
http://forums.iboats.com/bbBoard.cgi?a=viewthread;fid=28;gtid=1264197

 

[F_R]

Re: Weak spark new components

300 rpm while cranking when? Plugs in or out? Spark with plugs out but no spark with plugs in is very indicitive of either slow cranking (plugs in) or bad stator or sensor coils. What are we missing here?

 

[bennysku]

Re: Weak spark new components

Well let me give a little background.....when I got this boat it started w/o problem. At the time I couldn't go faster than maybe 20mph and idled like crap. Come to find out someone installed ignition coils 1& 3 backwards, which caused the head gasket to blow. Once I replaced the gasket and an ignition coil that was arcing. The compression now matched all cylinders. It cranked and started twice, but then fried the red wire from the rectifier. Replaced that, and have been having issues since. So I figured maybe I had collateral damage to stator, while at it replaced the power pack. With plugs in and out - cranking speed is strong.

 

[perkdp]

Re: Weak spark new components

You get spark when pulgs are out ? How, with the plug attached to the plugwire laying on the head or spark jumps from the plug wire to the head ?

With the plugs in, how do you know you're not getting a spark ? Are you attaching a spark indicator to the wire or something ?

 

[bennysku]

Re: Weak spark new components

I am using a spark tester with the plugs out. Also with plugs in I've used the spark tester and tried timing light.

 

[perkdp]

Re: Weak spark new components

i didn't see it mentioned, but assume that you're using the ignition key / start position in both cases. it sounds like a wiring / grounding problem to me. wish i could give you better info on where to head for a diagnosis.

 

[ezeke]

Re: Weak spark new components

Benny, are you able to turn 300 RPM with the spark plugs in?

Are you keeping the chokes closed all through the attempt to cold start the engine?

QL77JC4 @ .03?

Solid Core plug wires?

 

[bennysku]

Re: Weak spark new components

I am using the ignition key switch while testing. I would of suspected that if I didn't get spark with plugs out. I also tested with black/yellow wire removed from power pack. No diff.

I am getting 300 rpm with plugs in. I'd say 70% of the time I do have choke on - figured it'd help keep cylnder walls lubed with all this cranking.

I did try adjusting the sensor coils closer to the flywheel - a bit more spark, but still inconsistent. Now that I've moved them is there a good rule to set them? I know they shouldn't touch the flywheel but how far off should they be? Voltmeter test matches expected values from the service manual.