No Compression, Big Leakdown, and No Power 200 EFI

[bmcclain]

Let me start out by saying I have dealt with engines most of my life, but this is the first 2 stoke I have messed with.

I have a 1999 200 EFI serial #0G939416. Making noise last time out, wasn't sure where from, but knew it wasn't right. Checked it out while on the water and found yellow wires going to the top rectifier had come unplugged, due to getting hot and expansion. The terminals on both sides, male and female, were burnt.
After plugging the wires back in, the motor started up, idled fine, but was low on power and took 20 sec to plane out.
Once I got it home I found the 2 coils on the stator burnt out, totally black, so iI replaced it along with 2 voltage regulators (rectifiers).

Took the boat out yesterday for the first time since repair and same thing. It starts up quick and idles fine, but low on power and takes forever to plane out. Couldn't get it to run over 4800 rpm

Checked compression tonight and found cylinders 1-5, between 110 and 115 psi. #6 cylinder is zero. Leakdown on #6 checked at over 90%. It sounded like air was going out both the exhaust and intake but not sure

Wondering what to do next? I know issue is #6 cylinder, but what is the symptoms of a broken reed?
Should bite the bullet and go ahead and pull the head?

Also, what is a good service manual to purchase? Sounds like I'm going to need one.

[grybrd]

A broken reed would not give you the compression or lack that you are seeing. Time to pull the head and be prepared for the worst. Likely a blown cylinder: severely damaged piston and cylinder wall. Rebuild would remove the cylinder sleeve and install a new one, replace bearings, rings, pistons, gaskets, etc. BUT the reason for the damage will need to be determined with certainty to avoid a repeat.
Sorry, but I think you are in for a rebuild from the way you described the symptoms.

[JOE54]

^^^^ indeed

[Rip Bass]

Hard to get a zero reading without serious cylinder damage.

[bmcclain]

Removed head tonight. #6 piston had a hole on the exhaust side. Looks like ring gap was hanging up on port and ring finally broke. Beat the head too. All the other cylinders look new and can still see the cross hatch in the bores.
Now have to decide to rebuild or just buy a powerhead. Planning on pulling it off this weekend either way.

[EuropeanAM]

Pictures would be a good idea.

You can also find more engine-specific info here:

Mercury - 2.0/ 2.4/ 2.5 Liter High Performance
For discussions related to 2.0/ 2.4/ 2.5L motors (Carb, EFI, Optimax or Racing).

[bmcclain]

Yeah, I'd like to post pictures, but could not get them to load. Even after resizing.
I'm going to take the boat to Paul Nichlos next week and let him fix it.

[EuropeanAM]

He'll get you fixed up.