1987 Merc 200 hp Carb Basket of Warms! Warning Alarms, Mods, and deletes

[slpcamaross97]

Well i finally joined the S&F world. Ive had fun with my BBC Io pantera boats, But wanted something smaller but still capable of rough water and wanted OBS(yep Twins).

Boat is a 1987 24ft Aero (Klem Gem Similar to Pantera and all the other copies of the 24/7 design boats). With Twin 200Hp Merc Carb engines SN# 0B156538. On offshore gil mounts. Has low water pickup nose cone kits.

First off, Im very technical guy. But new to the 2 stroke ob world. So go easy on me.

Searching though the site, I see the first recommended mods would be to Delete the oil injection system and go pre-mix to save the motors. I like the idea of oil injection(boat is twin 200s).
-Has anyone just replaced the drive gear to keep the system running for another 30 years?
-Or just pull it all off and pre-mix it in a gas caddy?

Second mod i see is Deleting the Black boxes?
-If i had to guess this would be the idle stabilizer modules and locking the timing down at 22 Deg BTDC?
-But maybe i need to delete way more than that?


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Alarm issues.... I have both motors (starboard one more) that will sound the Solid BEEEEEEEPPPPPPP.
Happens at idle or while on plane. Comes and goes. Temp gauge(no actual degree indication) is below by one hash mark(Or below that mark when idling out of the channel). Comes and goes. but cant seem to pinpoint who is causing it... Ive searched around and seen that a oil injection issues should be a Beep-Beep-Beep... but other posters have found oil injection stuff causing the solid beeeeepppppp.
-Any good way of diag what sensor is causing the warning? -My idea was to go to the junction block for the tan wires and remove one at a time to see what one is causing the alarm? (kinda like input and output diagnosis to the warning module...)

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What else should I inspect and make sure is OK talking general ob stuff like Reed-valves, Mechanical timing, sensors?

[Motv18]

I can clear up beep beep beep vs beeeeeeep one is low oil other is no oil. Sensors and such are also solid beep. Normally.

Stock rpm the oil system is ok, cost to fix is main reason to delete. Same with switch boxes and idle stability also you control the oil and many like that.

Are both thoes rh?

Most you can disconnect the sensor and jump. A lot of ohm testing as well service manual is downloadable fairly cheep.

[flabum1017]

As said above, no oil can cause a solid horn; bad tank sender. A solid horn can also be caused by overheating. If you don't already have an IR temp gun, you should get one. Shoot the top of the block on both banks when the horn is blowing.... I think the alarm is supposed to sound over 200 degrees, you should be nowhere near that, should be 140 - 160 ish at idle maximum.

[slpcamaross97]

As said above, no oil can cause a solid horn; bad tank sender. A solid horn can also be caused by overheating. If you don't already have an IR temp gun, you should get one. Shoot the top of the block on both banks when the horn is blowing.... I think the alarm is supposed to sound over 200 degrees, you should be nowhere near that, should be 140 - 160 ish at idle maximum.

Thank you for clearing up the horn warnings. Makes more sense.

I do know that i have the 240 degree sensor/sensor location per the service manual. The engine could have either a 190 or 240 degree sensor.

I have decided to read though the complete service manual. I just finished the power head section and things are making more sense now.

As of right now. Im going to delete the oil system and go pre mix. Ill test the retard/advance module(its one on my boat) to verify its working as it should.

[Merc 2.5]

The timing advance/idle stabilizer need b throwed n river , then do full link&sync , have you done the basics ?? Compression ,fire,fuel? If all gud then start deleting oil and boxes, that black box can malfunction and send ur timin thru the roof or sumthin and boom,

[slpcamaross97]

The timing advance/idle stabilizer need b throwed n river , then do full link&sync , have you done the basics ?? Compression ,fire,fuel? If all gud then start deleting oil and boxes, that black box can malfunction and send ur timin thru the roof or sumthin and boom,

Simple answer is not yet. The carbs are leaking fuel from various places. And it was sitting for a year or 3. Last time I have proof of running good was 2015.
So working through the systems.

Now I found something interesting tonight... sometime between 2015 and now the t-stats were removed totally. No restrictors or anything. Could this cause the engine to run on the warm side?