89 black max v200's

[halibob]

Ok, i'm impressed with the knowledge that some of you guy's have on my particular engines, and it seems like you like a challenge so here it is. I have twin 89 200 hp carbureted black maxes with about 1100 hrs on them. The compression is great and consistant on both, and they generally run great but do have some quirks that bug the heck out of me. The port engine tach drops off completely but intermittantly. One mechanic said it probably has something to do with the voltage regulator. I forget how he explained it , but to the effect that when the batteries are chaged, it dumps the charge someplace else and the tach stops. It's understandably hard to diagnose an intermittant problem, but the tach comes back within seconds, never out for more than about 20. The other thing is with the water pressure guage. I get enough pressure, but it always wavers between 10 and 20 psi. I have replaced the pump asy., poppet asy., thermostats, and it still does it. It never overheats and there's always water coming from the telltale. Know for the starboard, the water pressure guage psi increases with the rpm's but tops out at about 25 psi which i believe is normal, but again, no overheating or any water flow problem. The main concern with this engine is at about 4400 rpm, it acts and sounds like it either 4 strokes or is being choked. It loses power and gets a deeper or throatier sound and vibrates a bit, so i only run at no more than 4200 rpm. At that , i'm running at about 27 -30 knots and get about 1.17 nmpg. The problem is that i can't get a mechanic to come out with me to diagnose it and it has to be under load to see the problem. I don't know if its a fuel or electrical thing, but i would like to find out, and if anybody can help, it would be greatly appreciated. The hp doesn't change from 4400 rpm on up to 5600. Other than that, they work great and i have learned to just leave well enough alone and with reg. maintenance and care , i have gotten 4 yrs. and 500 hrs. of otherwise trouble free use out of them.

 

[bigshrimpin]

Re: 89 black max v200's

Get rid of the Spark Advance Modules. I bet that is your problem. You don't need them and you find out what those motors have been holding back for many years.

You will also extend the life of those engines by removing the oil injection and propping the engines so they turn at least 5800rpm

I'm still running a 1981 v225 and 1979 v200. I love them both and run them hard.

 

[WillyBWright]

Re: 89 black max v200's

You might have a carb main jet restriction, or you might be losing spark at higher RPMs. Both are about equally likely. The carb issue could be a tiny piece of hose, or varnish. The spark issue could be a bad stator, or a bad switchbox. The carb possibility concerns me most because it could lead to some serious damage. The spark possibility is more annoying than damaging. The carb possibility would keep the motor running fairly smoothly. The spark possibility would make it run a bit rough above 3/4 throttle or so.

I believe the spark advance modules referred to are the idle stabilizers. They can cause problems and you can live without them.

The water pressure problem may be debris wandering around in the hose to the gauge. Pop it off of the gauge and blow back to the motor with some compressed air.

The tach issue could be a bad connection. I'd suggest cleaning and tightening the battery connections, and removing and reinstalling the voltage regulators which may correct a loose or corroded connection there.

Also, make sure there is a hefty jumper between the negatives of the batteries. I don't think that lack of one would cause the problems you mention. But make sure there is one to avoid other problems. If those water pressure gauges are electric instead of mechanical (wire instead of hose), that could be causing your gauge problem. Probably not the tach problem, but gauges act funny without the jumper.

 

[halibob]

Re: 89 black max v200's

Thanks guys, i'll give those suggestions a try. I'm leaning towards the electrical side as being the culprit, as the carbs have been rebuilt and serviced by three different mechanics, and i would think that if there was a problem with them, they would have been discovered, but you never know. I was thinking of the main jets also, and will check them and make sure that they are the right ones and clean. As far as propping goes, they are propped down, and will easily rev to over 6000, because these engines will push the boat to over 55 mph, but the hull is not designed to go that fast, but once i get the problem sorted out, i will definetly cruise at a faster engine speed, say 48 to 5000. As far as dumping the oil injection system goes, i would need to install a good fuel metering system in order to mix accurately. The boat (stamas 255 tarpon) has a 158 ga. fuel tank. As soon as the weather cooperates, i will give these a try and post the results , thanks again. Bob

 

[gss036]

Re: 89 black max v200's

Have you checked a Mercury OEM manual for your engines on the water pressure in psi? I ask because I run a 1989 200 hp Black Max, (since new) and my OEM says 12 psi at (WOT) 5500 RPM. That is about what I run at 42-4400RPM. Maybe, somewhere along the line someone installed a high pressure water pump to get you those pressure readings. Do you have 2 seperate guages (1 for each engine) for water pressure?
My manual says it is for 1989-1990 Models 200/ 200XRi w/ sr# 0C100861 thru 0C291519.

 

[halibob]

Re: 89 black max v200's

I have the mercury manual and the specs read a MINIMUM of 12 psi. @ 5500, but no mention of a maximum, and they are two seperate guages with lines directly to the guages, however, the hose setup is a little bit different on engines and the lines going to the guages are a bit different. The port is a little larger in diameter and of a softer rubber type hose while the starboard hose is a harder plastic type hose, and my manual covers engines with ser. #'s C100861 and up for models v-135 thru v-200. The water pressure is proportionate to the engine speed. At idle, i don't get a reading, at 4500 rpm i have about 20-25 psi.