Replaced stater and rectifier, still no spark in one cyl

[Cady8special]

I’m at a loss here. Just picked up a boat with 40hp merc 3 cyl 4 stroke. It bogged under load, but did get up on plane once. Any time I gave gas after that it would slow or die. Batteries weren’t charging either, same voltage running or not. So I got a new stater and regulator/rectifier and it still seems like I’m not getting spark in the second cyl. When I spray gas in cyl 1 or 3 it bogs. Cyl 2 there’s almost no affect by it. Same if I cover the manifold and cut the air- cyl 1 and 3 slow down, cyl 2 is not really affected. What else could be causing this issue? It’s not plugs or wires I tested that.

 

[Sugo]

Did you test the compression?

 

[Cady8special]

Did you test the compression?

Yes it was 115-130 on all. 210 each at wot

 

[roscoe]

210 each at wot

What ?

"seems like I’m not getting spark"

Have you actually tested for spark?

Model/serial number

 

[Cady8special]

What ?

"seems like I’m not getting spark"

Have you actually tested for spark?

Model/serial number

Serial 0t42660

I tested spark a few days ago and it wouldn’t jump a 30 kilo gap while the #1 cyl would. Today I put a timing light on, and all 3 make have spark according to the timing light. But when it’s at idle on muffs and I spray gas into the manifold, it Boggs on #1 and 3 but almost no affect on 2. Same if I cover the manifold and starve it for air. 1 and 3 bog, 2 not so much

 

[Cady8special]

What ?

"seems like I’m not getting spark"

Have you actually tested for spark?

Model/serial number

The compression went up to 210 on each cyl when I opened the throttle all the way

 

[gpfishingdude]

Might have to run a better ground to the coils for those cylinders. That was what I had to do to get spark on two out of four on mine.

 

[Cady8special]

Might have to run a better ground to the coils for those cylinders. That was what I had to do to get spark on two out of four on mine.

It just ran good for about 10 seconds- good throttle response. then back to running crappy. So it’s some kind of intermittent issue

 

[roscoe]

If the spark would not jump a .030 gap, there is the issue.
I would swap your # 1 coil assembly with your #2 coil assembly.
Then check for spark again.
If the issue moved to #1 cylinder, then you need a new coil.

I'm pretty sure the plug wire is part of the coil, so don't try pulling them apart.

 

[Cady8special]

If the spark would not jump a .030 gap, there is the issue.
I would swap your # 1 coil assembly with your #2 coil assembly.
Then check for spark again.
If the issue moved to #1 cylinder, then you need a new coil.

I'm pretty sure the plug wire is part of the coil, so don't try pulling them apart.

Not a .30 gap- about a one inch gap on the spark tester. 30 kilovolt gap

 

[Cady8special]

Not a .30 gap- about a one inch gap on the spark tester. 30 kilovolt gap

Messing with carbs now. Evened out the suction on each carb -they all draw the same amount of air in now. Before it was like cyl 1 was doing all the work, now it’s more even, but still bad throttle response

 

[Cady8special]

Just water tested after getting carbs synced. Idles great, bogs at 2k rpm. Nothing I can do. Compression is good, spark is good, carbs seem good.