200 1998 oceanpro lost power

[interd0g]

The 1998 200 oceanpro has lost some power and no longer gets over 3750 rpm or so.
I replaced the plugs and filters - the plugs looked normal-ish. It starts, idles and runs great except wide open
I'm not sure about the full throttle advance screw which I may have lost position in an earlier fiasco.
I rung around Antigua and no one heard of a timing light, so that will have to wait a while till I go somewhere civilized.
Could any one give me an initial dimension for the gap from timing rotor in idle position,where the wot stop bears on, to the wot timing screw end cap when adjusted correctly. Or some other way to get in the ball park.
It seems to me that gap must cover around 18 degrees at the centre. Or maybe I am fos.
I realize this is not kosher, but I am 1200 miles from a competent tech.
I assume all responsibility!

 

[daselbee]

Re: 200 1998 oceanpro lost power

I will see if I can get down to the shop and do some measurements for you (today).
This will not be a good way to do the timing, because there are very small tolerance differences in the location of the timer magnet ring on the inner hub of the flywheel. Think of it this way....one turn of the WOT timing adj screw has the effect of one degree change. Pretty sensitive. And, the spec is 18* BTDC, plus or minus one degree....

I have two motors that I know are timed perfectly. I did them myself, and I will take measurements off them. If they measure the same, I will be surprised, but I will post the results anyway.

Get a timing light!!!

 

[interd0g]

Re: 200 1998 oceanpro lost power

Thanks - I appreciate your help and your time.
An added observation is, once in a while the motor surges up very briefly to something like full power for a moment.
Next time I go the The States I am going to pick up the compression tester and the timing light.
Meanwhile I will have to muddle through.
Its hard to believe how they get by here - it hasn't changed much since Nelson was around- its the same in all the trades.

 

[daselbee]

Re: 200 1998 oceanpro lost power

Ok here is the info you wanted, I think....

I was only able to do ONE MOTOR. I forgot that I had disassembled the other one that I wanted to include in these measurements. Sorry.

The measurements are to about 1/32" tolerance. I could not get them exact.

I did these measurements with the throttle linkage disconnected so that I could move the mechanism freely.
There are four measurements, basically all of them being screw thread lengths as they protrude through the threaded fixed point which, as they are screwed, allows adjustment. I measured to that threaded "boss" from the point where the rubber bumper ends, in other words, the total length from the rubber bumper contact surface back up to the threaded boss. Very hard to describe.
Make absolutely sure you understand what I am measuring.
The screws referenced are the descriptions as OMC named them in the OMC service manual for a 1996 200HP, starting around page 1-50.

Here we go....
1. The screw that locates the closed throttle position, "Throttle Arm Stop Screw (D)" has 1" of exposed thread to the contact end of the rubber bumper.
2. The Screw that stops throttle linkage travel at WOT "WOT Throttle Stop Screw (E)" has .5" of exposed thread to the contact end of the rubber bumper.
3. The screw that actually adjusts the timing; "Full Advance Timing Screw (C)" has .75" of exposed threads to the contact end of the rubber bumper.
4. As you open the throttle, a gap develops between the end of the "Throttle Arm Stop Screw (D)" and the boss it contacts. Simultaneously, the timer base lever rotates and approaches the "Full Advance Timing Screw (C)" rubber bumper. Exactly when the timer base lever hits the rubber bumper of the "Full Advance Timing Screw (C)", the gap that has opened up is 13/16".
The engine linkage is NOT at full throttle when the WOT Timing bumper is contacted.

I hope this is what you wanted, but I think this is a very risky way to get your timing set up. Watch your plugs very carefully, looking for a too hot condition, and listen carefully to see if you can hear pinging....good luck.

Post back with the results on what you did.....

 

[interd0g]

Re: 200 1998 oceanpro lost power

Fantastic. A million thanks. I think the wot timing screw situation is not far off from where I calculated for a 18 degree angle using schoolhouse trigonometry.
I will be back on the boat tomorrow and will post a full account fyi.

 

[SparkieBoat]

Re: 200 1998 oceanpro lost power

sounds like a possible fuel problem, have you checked all fuel lines and carbs?? also fuel pump could be going, they generally last a little over 10 years or so.

 

[interd0g]

Re: 200 1998 oceanpro lost power

Thanks Sparkie. Once I am sure the timing is at least close, I am going to do what I can to check the fuel situation.
Like I said, two plugs look quite dry and brown compared to the rest. They have all always looked a bit oily in the past when everything was good. I assume a carb is right next to the cylinder it services?

 

[SparkieBoat]

Re: 200 1998 oceanpro lost power

the carbs on that model are easy to remove and clean, pay special attention to the needle valves and that passage. it is bad to run a motor with partially clogged carbs, can cause real damage

 

[daselbee]

Re: 200 1998 oceanpro lost power

I assume a carb is right next to the cylinder it services?

NOT SO.....The intake is designed in such a way that there is a crossover effect.
#1 cylinder is the highest cylinder, and it is on the starboard side.
The carb for #1 cylinder is also the highest carb, BUT it is on the PORT side.

Same way with all the others.

#6 is the lower cyl, and is on the PORT side. The carb for #6 is the lowest carb, and is located on the Starboard side.

 

[SparkieBoat]

Re: 200 1998 oceanpro lost power

do the loopers 60 degree motors do that also???
I thought that was only on the 90 degree crossover motor.

 

[daselbee]

Re: 200 1998 oceanpro lost power

do the loopers 60 degree motors do that also???
I thought that was only on the 90 degree crossover motor.

You have some terms mixed up....
The engine that he has is a 1998 200, which is a 90* V6 looper.
The intake is designed with that crossover carb/cyl pattern.

I think you are referring to "crossflow" motors, which is not the same thing as the carb/cyl cross at all.

Loop charged and crossflow charged motors get those terms from the way the fuel/air ENTERS the combustion chamber, and the flow pattern it follows while "swirling" in the combustion chamber. Crossflow engines have a distinctive large dome covering only half of the piston top, while looper motors have a relatively flat piston top.

 

[SparkieBoat]

Re: 200 1998 oceanpro lost power

thanks for the edumication...now I know..LOL

 

[interd0g]

Re: 200 1998 oceanpro lost power

I inspected according to the daselbee measurements and adjusted the wot timing screw. It was not far off.
I wanted to be sure all 6 were firing. I removed the caps one by one while idling.
Surprising how little difference to the idle one missing cylinder makes to an uneducated ear. I see you could lose a cylinder and think you were fine at low rpm.
All I could notice is that when putting the cap back ON a firing cylinder there is a slight and momentary acceleration.
Well , on cylinder 5, there was no difference noticeable whatever. Also this plug was much wetter than the others.
It had a terrific spark when removing the cap - rubber gloves were an advantage. It was till jumping with the cap 1/2 inch away.
I put another plug in there but still the cap on/off test showed zero detectable difference at idle. I feel like this test is inconclusive.
This test works great on my car which only has 3 cylinders
I did my best to clean up the carbs short of dismantling, replaced filters and cleaned the collection tube and strainer in the tank.
Subsequent sea trial I got close to 4000 rpm at wot. I never had to get close to wot before for 28 knots so I think there is limited power.
I get the feeling I really need a compression tester.
Is this degree of power reduction consistent with one cylinder loss?

 

[jonesg]

Re: 200 1998 oceanpro lost power

.
Well , on cylinder 5, there was no difference noticeable whatever. Also this plug was much wetter than the others.
It had a terrific spark when removing the cap - rubber gloves were an advantage. It was till jumping with the cap 1/2 inch away.




I get the feeling I really need a compression tester.
Is this degree of power reduction consistent with one cylinder loss?

I'd say yes, they will run with a dead cyl but be down on power.
Odd that it has strong spark ( it should jump almost 1/2 inch), but doesn't seem to be firing. Did you put your hand on that cyl head to see if it is hot as the others? The only thing I can think of is low compression or water.
Sounds like you have the right idea with the compression guage.
Compression is usually at the top of the list when diagnosing.

 

[interd0g]

Re: 200 1998 oceanpro lost power

Thanks for all the advise so far - the saga continues;-

I found a compression tester on the island but still no timing light.
People don't believe me, but our yellow pages are A5 size and 90 pages. The only o/b agency is Yamaha but they seem to get by without any test equipment.
Oh well, don't stop the carnival.
So, my compressions range from 100 to 120. Cold.
After a short session at wot I checked the head temperature using the time/discomfort method. They were all much the same except I could tell the bottom two (3 and 6?) were a little cooler. Maybe they get the first water.
The time -to - discomfort period (DTD) was 10/15 seconds. I was surprised how cool the engine was - not like the average car.

All the plugs looked similar after the run - quite damp but the run back from the entrance to the harbor has to be done at 1200 rpm and then docking at idle.


The power is low ( 3750 rpm at wot) but perfectly steady and consistent.
Cleaning the pick up hose and tank strainer got rid of my check engine light which I understand is just an excessive suction indicator for fuel.
Looking at the manual, the item "low wot rpm" ticks off almost everything so this may take a while.

What would you look at next?

 

[interd0g]

Re: 200 1998 oceanpro lost power

Replying to self ( meet a better class of person).
This thread is going on a bit, but the mystery is still with us.
Having checked the compression (not that bad) and having strong sparks some one suggested try to see if main jets spraying all and equal.
I can't check anything under way as once out of the harbor its the open Atlantic. You hang on -its almost never calmish.
So I moored bows to the dock with stong lines and opened up astern for a minute or two.
I observed what I imagine is the main jets, spraying. I then bunged up each throttle opening with the hand in turn for a second.
Buckets of fuel accumulated in the throats and the motor sputtered until the excess gas cleared.I'd say they are all getting a good feed.
I had a Honda 2 cylinder generator once. One cylinder would stop after 5 minutes. The mechanic failed but wanted $1500 anyway ( thought it was a compression problem , did the wrong stuff - has no gauge - no light). Cylinder had gas and spark when failing.
What was it? In the end i found out by substitution the coil concerned produced a good spark but at the WRONG time!
Tricky, I admit, but I always worked 'no fix no fee" myself ( electronics - mega charter yachts))

 

[daselbee]

Re: 200 1998 oceanpro lost power

Well it is certainly possible for the engine to be firing at the wrong time...

Your flywheel has a magnet ring around the center hub. They are known to come loose, the glue deteriorates, heat, etc.

If it moves 1/4" then your timing will be way off, and you won't get full power.
Sometimes they move around, and the engine runs great, then bad, then great...

Here is a way to tell....Get a timing light!....(Joke)

Or, pull the flywheel, inspect the center magnet ring. Sometimes the original manufacturing paint marks that they used to align the center ring are still there. Someone on this site once posted pics of the correct magnet position. It is positioned with regard to the thin slots that are made into the magnet. I think it was Ezeke that had the pics, but I am not sure.

 

[interd0g]

Re: 200 1998 oceanpro lost power

I found a bloke with a timing light, so he says. I will have to pay to have him use it, as he is supposed to be the local o/b specialist.
I hope it works out - he doesn't believe in having books and his back yard is a graveyard of o/bs with vines growing through them!
I will be there breathing down his neck.
I won't have a chance to get one until my next trip to the US.
Are there marks for the other 5 cylinders in the flywheel - I didn't notice?

 

[daselbee]

Re: 200 1998 oceanpro lost power

No other marks. You have to make your own. Pull the plug for each cyl, rotate the engine by hand, place a screwdriver in the plug hole touching the top of the piston. Rock the flywheel back and forth feeling the movement of the screwdriver, and locate TDC for each cylinder that way. The screwdriver will come out, and then go back in as the piston travels thru TDC.
It takes a very fine touch to get TDC this way, but it works.

Put a white paint mark on the flywheel at the timing indicator loc. That is TDC. Remember, the 18* mark is not there for those cyls, just #1.

I describe this method simply because I suspect you do not have a piston stop tool to do it by the book.

 

[interd0g]

Re: 200 1998 oceanpro lost power

Your suspicions are well founded.
If I could pester you a little more.
Does the firing mark go in order 1-2-3......
round the flywheel CCW?
What is the firing order?