Mercury firing in 2 cylinders same time

[Davidpkl]

I have been trying to figure out my mercury 40hp 4 cylinder 2 stroke for a wile now And I can't seam to figure it out I have replaced stator, trigger and switch box so far motor starts up and idles great but now it bogs down and acts like it has no power so checked timing and noticed when I hook light up to #3 I don't get much of a flash it pretty much just stays on when I hook up to 1 2 4 they all flash good. So I marked Top dead center on my flywheel for all 4 cylinders and checked each cylinder individualy and 1 2 4 all only show it firing on the cylinder I am hooked to but when I hook to 3 it showes to be firing on 3 and 4 at the same time. Is this normal? And if not what do I do now?

[Davidpkl]

Could a bad rectifer regulator cause this issue? It is the only thing I have not reaced. I did unhook it from the stator and ran it on a water hose but still was firing 3 and 4 at the same time.

[capnzee]

Got to be in the switch box.wires hooked up properly in accordance with color code? I don't believe it could possibly be the rectifier.

[R.grover]

What 40hp do you have? late model jap one?

[Davidpkl]

Got to be in the switch box.wires hooked up properly in accordance with color code? I don't believe it could possibly be the rectifier.

It is a new switch box and it is all hooked up right.

[Davidpkl]

What 40hp do you have? late model jap one?

It is a 1997 40hp 2 stroke 4 cylinder it is the mercury style not the old yamaha style.

[Tripps]

Swap out flywheel i had one go bad. Drove me nutz

[Davidpkl]

Is there any way to see if it is a bad flywheel? As I don't have one to try

[davemvegas]

Is there any way to see if it is a bad flywheel? As I don't have one to try

pull flywheel and check for even spacing between magnets. if two are slid together that would cause a problem like you have.

[Davidpkl]

Pulled flywheel and all magnets look good with no chips or cracks.

[Davidpkl]

Ok I figured it out had a old switch box laying around so I stuck it on there and what do you know it fires just as it should. Hopfully it runs good but wont know for sure untill I take it to the lake. Can't believe I had 2 bad brand new switch boxes what are the chances.

[FMP]

WHat brand boxes ?

[Davidpkl]

WHat brand boxes ?

Im not sure I will need to look. I bought them off eBay which I will never do again.

[FMP]

CDI , which makes a great product told me a couple years ago to be careful of knock off components that very closley resembled the original . Even some of the packaging was near the original with style and colour.

[Davidpkl]

CDI , which makes a great product told me a couple years ago to be careful of knock off components that very closley resembled the original . Even some of the packaging was near the original with style and colour.

Yea from now on CDI and OEM electric parts is the only thing I am ever going to buy.