1986 200 HP Black Max Vro still there - compression thoughts

[Jmhout]

First post go easy.
Well I am happy to say I got my first Ranger it's a 393v with tandem brakes and a Mercury 200 black Max.
Boat has been driven on canal and no wake areas for 5 years. The engine starts and runs well. No idle issues and seems to run at moderate speed just fine. Have not pushed it at all as we plan to do much maintenance...
New impeller has arrived and new fluids etc are for sure going in.
The major issue is we compression tested it and cylinder 2-6 are at 90. Cylinder 1 shows 60.
Before everyone jumps down the rebuild it now path I get those thoughts.
What I am wondering is should I decarbon first to see if it helps?
Key questions
1. Has anyone actually had an engine return to okay pressure?
2. Can I run it easy and get some use out of it as is?

Engine serial number is 0A980593.
I believe it is a
0A168044 THRU 0B290009 - MERC MAR 2.4L (EFI)
If yes should this post be in a different forum?

[SilverFox579]

This is correct forum for 2.4L. See the FAQ at top of this forum for correct procedure to test compression and ensure your test was done accordingly. A decarb might help but I'd wait for more experienced replies on your specific engine. Welcome to BBC.

[revlimiter]

I'd take a light and look inside the cylinder bores. If the cylinder with lower compression looks ok I'd go run the snot out of it and check compression again. If it's really idled that much in its life without being opened up it's due to run. You can also use some seafoam or a cleaner of your choice too.

[.44mag]

I had an issue with mine a few weeks ago, wouldn't get on plane and sounded like it was hitting a rev limiter while trying to plane out. It was idling rough as snot. One cylinder was at 105 psi the rest were 119 to 115 psi. I pulled the head off on the low side every thing looked fine. Put a new head gasket on and soaked all of the cylinders with carb cleaner for several days while I cleaned the carbs. It now runs a heck of a lot better and doesn't smoke any where as bad as it did prior to this work. Worth a try.

[Jmhout]

Thanks everyone for the respot so far!

[EuropeanAM]

If you've run the engine a bit, recheck the compression and see if there has been any change. Use caution- if there is a mechanical problem in there, it WILL get worse if you continue running it.

If the compression did not improve- might consider pulling that cylinder head for inspection (never know, might be as simple as a bad gasket).

[Jmhout]

Thanks. Waiting on title and paperwork to get her back in water again. Will post numbers again with an update.