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OK, so I have a 1987 20' Revenge WT with a 1987 Johnson 200 HP VRO. It's had a new water pump and cables installed. It's also been looked at by an outboard shop or two. It runs great out of the water with the water hose clam shell, and gets up to 6500 RPM. However, it performs terribly in the water. It spurts and smokes and cuts out because it runs so poorly. Under load it will not go further than 4000 RPM and it goes up to 29 MPH. I'm thinking that I should be able to reach the 6500 RPM and exceed 35 MPH. Any ideas out there?

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It is a very bad practice to run any outboard above 1500 rpm's while on a hose flushing device. Please don't do that again, you risk serious damage.

I would suggest your motor has a wide open throttle (WOT) range of 4500-5500. A owners manual and shop manual are good to have.

With no load, any engine can sound fine. Under load is a different story. A general guess is you have dirty carburators and they are not synchronized.

What is the history on the motor? When did the problems start? Last maintenance performed?

As for speed, we need more information about the engine mounting position and propeller brand and size.

Let's stick to the engine running problem first before discussing performance.

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The coil packs could be breaking down under load or there is a fuel flow problem. If you continue running the engine at 6500 RPMs on a water hose the problems might well become a moot point.
Zap

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On all the out outboards I've owned, whenever I had a problem such that you've described, the issue almost always turned out to be a dirty carb.

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No, it does not run great out of water if it is being pushed to 6500 RPM, it is being seriously abused and there is nothing great about that.

Do NOT under any circumstances, ever, ever allow an outboard to rev higher than 2000 RPM if it is not under load. A 1500 RPM limit is even safer.

That motor has a 6000 RPM redline under load so you may have already thrown a rod revving it to 6500 on a hose.

*If* you have not already caused serious damage by seriously over-revving the motor on a hose, you WILL cause damage if you continue that insane practice.

The obvious reason the motor will achieve high RPM on the hose and in neutral is precisely because there IS NO LOAD ON THE MOTOR so of course it going to rev high with nothing to stop it. That, in no way, tells you it "runs great".

If the boat runs poorly in the water then that tells you it is not running correctly. At 4000 RPM @ 29 MPH, I bet you have a 17" OMC prop, and the 4000 RPM at WOT tells us the motor is not generating anywhere near its full power. Given the age and brand of the motor I strongly suspect a bad power pack. Your 200 has two of them and they often cause a loss of power that does not necessarily prevent the motor from running at all.

It could also be as simple as one or two or three cylinders not firing due to loose spark plug wires or fouled plugs and fouled plugs themselves could be a symptom of a VRO pump gone bad which will dump excess oil into the fuel mixture.

Start with the simple, obvious and inexpensive stuff first: Check to see of the motor is firing on all cylinders, Check for loose spark plug wires, change the spark plugs. If no improvement after that, try swapping out a power pack one at a time to see if that fixes things.

Your boat should be good for speeds in excess of 40 MPH so something is very wrong and I'm sticking with my bad power pack theory. I've seen to too may times on OMC motors of that vintage.

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great info every one. I hear the words of warning about the over revving on the water hose. Thanks I wont do it again. It was not however a practice. just the once and very quickly to see if the rpm,s went up there and that was it.
is the fact that the motor is lowered into the water cause a load? is it that the water creates a back pressure on the exhaust port?
okay, tomorrow I will check the spark plugs and wires. then the power packs. Is there a test procedure for checking the power packs?
thanks,
RobertoCB

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When you talked about the motor running poorly in the water I believe the assumption was that the propeller was turning. It is the turning propeller that creats the load.

One procedure for testing the motors spark is, with the engine in the water and the propeller turning, to disconnect the spark plugs one at a time and listen for changes in the performance. Reconnect the plug wire and go to the next spark plug...... Others may have a safer way to perform this test.

Zap

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Actually....with having the motor in the water versus running it on a hose puts a greater load on the motor. A motor that runs well on a hose at idle may not run well at idle when the lower unit is submerged.

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my experience with this particular problem is either power pack or compression. the lower unit actually spinning the prop in the water places the load on the motor. if you have bad compression, your motor will not develop the advertised HP.

i just fixed pwerpack issues on my 90 = one powerpack went, and though the motor seemed to idle fine, would not turn over 2000 RPM ... quickly strained the other power pack to the point that i needed to replace both.

i think your motor is shot ... but i hope i am wrong and you simply have a fuel issue with your carbs, cleaning or rebuilding is an option. i go with a rebuild personally.

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Check for spark with a load (prop spinning) in the water, not on a hose. You won't feel a difference with just idle in the water if it's a spark issue.

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well, just changed the vro /fuel pump and the boat is running great and with out as much surging but still not reaching full rpm's. although it starts and runs so much nicer. so to date its gotten the new water pump, lower end serviced, carbs have all been rebuilt, new vro/fuel pump, new sparks new spark wires, new temp sensor, new cooling water pressure gauge, new fuel/ water filter.
still surging but not as much and still wont see 5500 rpm's! 4,000 only! compression is good on all cylinders and very close all within 3 to 5 psi. sparks came out and where a bit oil fouled but not terribly. perhaps the new vro pump will take care of that. next shes getting the new power packs. we shall see what happens!

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All, not tryingto hijack the thread, but what about testing with the lower unit submerged in a 55 gallon drum? Is that ok to go above 2000 RPM? Or does the water pump need the ram speed of the boat moving to provide enough cooling. Is it the prop spinning against water load issue, or the water cooling issue? Just trying to learn something here.

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The issue is the lack of load on the engine, not cooling

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I too am learning from this thread.
I have a 1997 Mercury 40 hp 2-stroke that I usually warm up at my house on the hose prior to heading to the boat ramp. When I first get it going, it is usually idling in the neighborhood of 2500 to 3000 rpm.
Based on the upthread responses, is this a bad practice?
If the issue is load on the motor, then waiting until it is in the water (but still in neutral) would pose the same problems, right?
What is the correct method for starting the motor cold?