200 HP Black Max Troubles

[MWBROWN]

We have a 1989 200 HP Black Max. It runs well at WOT.
There is terrible transition from idle to WOT. No midrange speed to speak of.

Here are three pictures showing some things on the engine.
We think something is missing.

Please look at and help if you can.

A manual is soon on the way.

Thanks,

Mike

 

[2Smokinya]

Re: 200 HP Black Max Troubles

Hard for us to diagnose this problem, the manual you ordered is the best way to go right now.

 

[hkeiner]

Re: 200 HP Black Max Troubles

What is the serial number of your motor? That would help a lot.

 

[gss036]

Re: 200 HP Black Max Troubles

Somebody has removed the oil injection system from the engine. I am presuming that you pre-mix 50-1 gas/oil. The small inline fitler looks like it is really old, change it w/the correct filter. If you don't have a feual/water seperating filter, you really should install one.
It looks like your bleeder lines are in tact, so ok there.
I would only being taking a wild guess at this point, but here goes. First would be to rebuild the fuel pump, very cheap and only takes a few minutes, you may have a small hole in the diaphram. Instructions come with the kit so you don't need to wait of the anual to do that.
You run ok at idle/low speed, lean mixture on the carbs. You run good at high speed, again caused by a lean mixture. Continue running with a very learn mixture from the carbs and you will probably burn a hole in a piston or cause severe scoring on the cylinder walls.
The first step is a full rebuild/cleaning of the carbs. Then do a decarb(look at FAQ for mixture/method)
I have an OEM manual for that engine if I can be of help until you get yours.

 

[j_martin]

Re: 200 HP Black Max Troubles

I would get the manual, study it until you understand the linkage adjusement and synchronization (link n sync, as we call it) and be sure that is set up right. Tinker mechanics often get them totally out of wack, and it can't possibly run right through it's range unless it is right. About all you need is an induction timing light, some hand tools, and a couple of drill bits (for setting the throttle cam gaps.)

Also, if you have any replacement fuel connection or hose parts that aren't genuine Mercury, change them out. Mercury fuel bayonet parts are metal, and the hoses say Mercury. Many headaches are caused by substandard fuel parts on the big V6's. Parts that are fine on 3's and 4's just aren't up to snuff for the fuel flow needed by these things.

The regular maintenance items (fuel pump, filter, etc) apply.

Hope it helps
John

 

[red cobia 17']

Re: 200 HP Black Max Troubles

I have a 225 carbed engine and had a simular problem with my engine.It didn't want to run well at low speeds but ran good at high speed.I put my boat in the shop and they found 5 of the 6 check valves in my bleeder lines were clogged.They replaced them and it runs great now.I'm not sure if your engine has them or not but it's worth a look.There are 3 check valves on each side of the engine.Oh my engine is a 1996 model also.

 

[MWBROWN]

Re: 200 HP Black Max Troubles

Thanks for the feedback.
1989 200 hp Black Max OC199873 21ft Renken
I take it that the oil injector is sucking vacuum? If so, the two ends need plugged, correct.
We will change the inline filter and pump soon.
Yes we are mixing the oil correctly.

Again thanks. I will post any results as soon as we get to some water.

Mike

 

[gss036]

Re: 200 HP Black Max Troubles

No, the oil system is not a vaccum. Did you take it off? If so, did you install the kit required for the pump shaft to the grear on the crank shaft?
The oil is pressure fed from the lower starboard side of the block. It pressurizes the boat tank, flows to the engine tank, which if gravity fed to the oil pump, which then blends w/gas a fed to the carbs. Hopefully you understand the system and get it right before problems are created.

 

[MWBROWN]

Re: 200 HP Black Max Troubles

Nope, we did not take it off, it is just not connected. I thought it might be vacuum driven.
It is in the pictures.

I will wait until the manual gets here.

Thanks all.

Mike

 

[j_martin]

Re: 200 HP Black Max Troubles

The oil pump is mechanically driven by a plastic gear on the crank. (One of Murkery's more idiotic moves in most everyone's opinion.) They fail sometimes if you abuse them, like running cheap gummy oil, running out of oil, or extreme overrevving or overheat. Up to about 6500 rpm, they are usuallly just fine. When it is disconnected, it should be removed and a block off kit installed. That kit retains a bushing that might fall out into the motor with catastrophic results if it isn't retained.

It just dawned on me that the hack that disconnected the oil pump withoug actually removing it and replacing it with the proper plug off kit might have removed the advance module and retimed the engine. That's OK if you only run at idle and WOT, but if tends to make it run a little ragged in the midrange. Timing normally advances fully by mid throttle. The advance module changes the bias on the switchboxes and advances it a few degrees more, usually above 5000 rpm. Something worth investigating. You could check it out using the manual and looking up the parts at mercurypartsexpress.com using your serial number

hope it helps
John

 

[MWBROWN]

Re: 200 HP Black Max Troubles

J Martin,

Thanks for the information. We of course have no idea who disconnected the injector, but the symptoms you spoke of seem close to what we get.
Good idle, some low end acceleration, and the on to WOT. Little to no midrange.

Thanks again,

Mike