Weak spark? '98 Johnson Venom 200 j200stl

[Dentpusher]

Background. Engine has really never run perfect, it's always been a bit "lopey" @ fast idle and an occasional "lean sneeze" since I bought the boat in 2000 (a mechanic early on said that the sneeze was HARD to fix and suggested living with the sneeze), EXCEPT for one week, 2 summers ago. I had done my annual decarb with Berryman's instead of Seafoam and the thing ran GREAT all week. We get back down to the lake a couple weeks later for a weekend and it's running as usual again. Then last summer it ran similar, on our last weekend out until I could definitely feel a miss even underway for the first time ever and it would not rev normally like it usually does. Now I am trying to diagnose. Cold compression test revealed 95 in #6, 105 in #1 and 100 in the other 4 cylinders (lower than what I would like but no visible scuffing and cross hatching is still visible with a scope). I had some of the cheap "in line" spark testers and found #1 cylinder had WEAK visible spark so I swapped 1&3 coils and the weakness stayed on #1 so I have put it through some paces since it seemed to be more involved than the ignition coil.

I acquired an OE manual on top of my SELOC ( hate that thing ) and grabbed my multi-meter. I jumped to the flow chart and went to "No Spark on One Cylinder" and went to STEP 4. My charge coils were 120V each side but passed the resistance and ground tests. STEP 5 - Sensor coil passed the Ground Test. On the Output Test #13 I got P - .194, .183,.186 S - .193, .195, .187. On test #14, P- .852, .251, 1.021 S- 1.015, .940, 1.066. Testing resistance in Sensor Coil #16, I got readings of between 350 for the low, 2@357 on P side and 2@365 to 382 Ohms on Starboard, with my Chinese "Fluke" meter. Test #17 was 233 Ohms and there was no ground in test #18.

With the poor results I had received so far, pointing to something in the Stator, Timer base or flywheel, I wanted to confirm how poor of spark I had so I got a couple, more sophisticated, adjustable spark testers and set them to 7/16 of an inch, as suggested in some of the other threads, and found weak, intermittent spark just about everywhere at that setting, hardly any sharp snapping, blue arcing at all while cranking with the other plugs disconnected.

I am preparing to pull the flywheel. What would the gurus here look for? Are there any other tests I should do before firing the parts cannon? Will a DVA make a difference in any of my readings (my meter has built in Min/Max button)?

PS: I had a new Stator put on about 10 years ago for overcharging condition. I understand it could be bad now too, especially since I just found out how bad it was to run with wing nuts on the main battery. This is a clean looking, fresh water only motor. I have seen some ugly, crusty stuff in photos online and mine looks nothing like those salty things.

Thanks in Advance!

Edit: I'm a believer in OE parts but curious if CDI makes good aftermarket stuff (like MOOG). The optional 5 year warranty is appealing if they make quality stuff.

 

[Bosunsmate]

i like cdi. Id be ohmn testing your stator at least

 

[Dentpusher]

OK, I acquired a couple adjustable spark testers. I removed all spark plugs and went through another spark test. All holes showed a pretty good spark at 5/16 gap so I wanted to confirm whether or not they could do 7/16 ( a measurement some other guys recommend ) which they also did very well with white/blue on ends spark.

While testing, I noticed #5 cylinder, lowest on Starboard side, was puffing significantly more fuel than the other 5 cylinders. I had not pumped the primer bulb as I was not expecting to try and start the motor. I held my hand over the plug holes, there was lots of fuel on my hand when placed over that cylinder and virtually nothing coming out of the rest. I have always monitored my plugs and never really noticed any significant difference between cylinders, I usually change them annually as we do a lot of idling for skiing and I run premix so they get kind of fouled. The set of plugs that is currently in it are pretty new (I changed them in the fall hoping that might fix my issue) and they don't seem to vary much in color to my semi-trained eye. Can a single cylinder get so much fuel that it acts like a spark miss? That is how the boat sounded and felt last fall, like there was a distinct consistent miss?

Unfortunately, all of our lakes around here are flooded and we can't put boats on them and I don't have a very large tank to put the motor in to put it in gear to try some load testing. I am limited to small speed restricted local lakes but can throttle up while strapped to the trailer.

Any suggestions?

 

[dingbat]

The set of plugs that is currently in it are pretty new (I changed them in the fall hoping that might fix my issue) and they don't seem to vary much in color to my semi-trained eye. Can a single cylinder get so much fuel that it acts like a spark miss? That is how the boat sounded and felt last fall, like there was a distinct consistent miss??

when was the last time you cleaned the carbs and adjusted the floats?

A sticky needle valve and or /float will cause symptoms like that

 

[Dentpusher]

Long time. 10 years. Also, this evening I did some work for a boat mechanic....imagine that. He was leaning toward a ruptured/worn VRO. He tried to explain it to me how it could result in loading up #5 cylinder all by itself but I was in a rush to get my work done and home.

 

[Dentpusher]

If I clean my carbs to check for dirt and gunk, I HAVE to use all new gaskets/carb kits, correct or do some of you clean carbs without using new gaskets. Seems dangerous not to.

 

[Bosunsmate]

i do reuse