1988 Johnson 110 intermittent misfire

[AlTn]

far from an electrician by any measure, but I think if you're seeing 160 v. a/c on several electrical outlets in the house, I'd 1. change the battery in the tester and retest 2. call an electrician or test myself if I had the know how to determine what's going on. Google the 160 v. on household outlet and see if you agree.

 

[AEROCOOK]

Just to clarify, I was getting a reading of 167 DC volts with the DVA adapter plugged into the wall socket. I cant explain the weird science behind such a reading but somehow the capacitor is converting 120 AC into 160+ DC volts.

 

[Fed]

Google ... ac voltage peak vs. rms

 

[emdsapmgr]

Looking between the two factory parts lists between your engine and the donor engine seems that there are a lot of similarities. The flywheels are the same part number. That means the magnetic markers on the timing ring are in the same orientation. That also means that the timer bases will count rotational movement the same. All 4 coils are the same dual plug in type. Neither power pack has quickstart or SLOWfunctionality. . So they appear to have the same functionality. The swap should work.

 

[Fed]

spark jumps 1/2 inch and is bright blue

I think you're tying yourself into an electrical knot here, IMO it sounds like a blocked up intermediate jet.

 

[1983 ercoa 21']

I had a similar issue it turned out to be plug wires even though they ohmed out good the new ones fixed my issue. So if you have a spare set try them.

 

[emdsapmgr]

Visually checking the intermediate jets would be a good idea. Pull the carb bowls off and have a look.

 

[AEROCOOK]

The carbs have been removed,disassembled and cleaned, the jets were removed and cleaned as part of this process and I blew out all orifices with compressed air, I'm confident in the cleanliness of the carbs. As for the plug wires, I installed a new (aftermarket) set last season but in order to eliminate them as a possible cause, I replaced them with the set off of the parts motor along with the coils. I also replaced the VRO pump with the conventional pump off of the parts motor and installed a new fuel line from tank to motor.
At this point I'm waiting for a good day to put it back in the water and see if there's any improvement.
Back to the topic of carbs, can anyone tell me if the 88 hp carbs are the same as the 110 carbs? I know the jets are different, but just wondering about the rest of the parts? (catalog doesn't show a part number for the main body so I cant do a part match comparison)

 

[1983 ercoa 21']

There should be a bore size marked on the front of the carbs . You have to remove the silencer to see it.

 

[AEROCOOK]

There should be a bore size marked on the front of the carbs . You have to remove the silencer to see it.

As it turns out, the 88hp and 90hp carbs are 1 3/16 and the 110 uses 1 5/16

 

[1983 ercoa 21']

You have the same luck I do. Lol but there is plenty of other parts there to cover what you have in it and that's what counts.

 

[AEROCOOK]

Back to square one, weak to no spark on the 2 port cylinders, here's what I've done so far.
Swapped all 4 coils and wires from parts motor, no change.
Swapped coils side to side, no change.
Installed new CDI power pack, no change.
Disconnected black / yellow kill wire, no change.
Swapped plugs port to starboard, miss stays on port side.
By process of elimination, I figure it's down to the stator or timer base and since I have spares of each, I'll swap them in tomorrow and see what happens.

 

[Fed]

What happened to the spark jumps 1/2 inch and is bright blue?

Did something change or...?

 

[AEROCOOK]

Well I swapped over the stator and still no spark on the top port cylinder. Next I swapped the timer base with the same result. Scratched my head for a while and decided to try another coil and voila, spark returned. The only explanation I can come up with is that there was possibly a poor ground on that coil?
Anyhow, I took some sand paper and cleaned the ground tabs on all of the coils and as of now, I'm firing on all 4 in the driveway, I just hope it stays that way on the water. Just curious about my poor ground theory, does it make sense?

 

[Fed]

Makes sense to me but I would have thought when you swapped the coils (Post #32) you would have inadvertently fixed any poor ground connections.

 

[AEROCOOK]

Makes sense to me but I would have thought when you swapped the coils (Post #32) you would have inadvertently fixed any poor ground connections.

Yes, I would think so, I even bench tested the coil that wasn't firing and it ohmed out good. I have no other explanation.

 

[AEROCOOK]

I had the boat out on the water yesterday, the misfire issue seems to be resolved and the motor reved out to 5800 just like it used to.
An expensive and time consuming lesson on the importance of good clean grounds.
One thing I noticed while cleaning the grounds is that the port head had paint on the coil mounting surfaces while the starboard head did not. The port head was previously replaced so I can only assume that someone wanted it to look pretty and gave it a fresh coat of paint including the mounting surfaces that are supposed to be bare. Still don't understand why the bolts didn't provide ground though.
Thanks to all who helped out.