2000 Johnson 150 Ocean Pro Will not rev past 1800 RPMs while under load

[nstocum]

I'm out of ideas on this one, need help bad. I recently purchased this boat and have had nothing but issues since. Boat compression checked out perfectly and ran great for about an hour the day I bought it. Second time out it bogged down and shook extremely bad @ around 1800 RPMs when leaving the ramp and has been doing so ever since. I can run it on the earmuffs and it will rev to around 2500-3000 for a short period (I haven't tried to hold it there out of the water). It also makes what sounds like a knocking sound when in gear at low speed. I can cruise around at idle without a problem. If I do not ease off the throttle while trying to get on plane it will stall out, but re-cranks without an issue.

So far I have checked/ replaced:

1. All six carb bowls were warped, replaced them all and did a carb kit on each.
2. Replaced all fuel lines including primer bulb.
3. Ran the motor off a separate gas tank and line system with brand new gas, same result.
4. Re-checked compression and spark- Perfect compression and spark on all 6 plugs.
5. Replaced Optical Sensor
6. Replaced Port Side Temperature Sensor
7. Replaced Power Pack

Side note- The VRO system has been cut off and plugged. It appears they did a good job plugging the line and cut the wires short enough that they shouldn't be causing an issue.

I have no idea where to go next.... any ideas?

 

[nstocum]

https://youtu.be/y2DYBmGfPtg

Here is a short video of what I am experiencing. The shake is visible, but doesn't do it justice. The whole boat RATTLES when I try to get on plane.

 

[Bosunsmate]

Whats the spark plugs look like now?
Have you checked timing? Made sure the flywheel is at 0 when #1cylinder is at TDC?

 

[Chris1956]

Is the motor overheating, allowing the SLOW system to kick in? Is the shift assist switch working?

 

[reiddo1]

https://youtu.be/y2DYBmGfPtg

Here is a short video of what I am experiencing. The shake is visible, but doesn't do it justice. The whole boat RATTLES when I try to get on plane.

For what it is worth, I have the same model and year of engine and experienced the same issue as you. Except for the carburetors, I checked timing, replaced spark plugs, and cleaned up the optical sensor with contact cleaner. Still the same problem persisted.. I read on either this site or another how the wires leading to your overheat sensors if run too closely to your spark plug wires could pick up a RF signal from them and trigger a condition such as you describe. I rerouted my sensor wires by even adding additional wire length through soldering so that these were as far away from the plug wires as possible. The problem disappeared. That was about four years ago and no issues since. Maybe it was coincidence but that is my experience.

 

[nstocum]

Bosunsmate- Plugs are oily and wet. I have not checked the timing, that may be above my head.

Chris- The overheat light has not come on once. I did think that it might be the SLOW system kicking in and shutting down cylinders. Do you know how to bypass the SLOW system to troubleshoot?

Someone else mentioned the shift assist switch on a forum. I did disconnect it and it actually made it worse. The motor would start fine, but then stall out after exiting the QuickStart mode while still in neutral.

Reiddo- My CDI Powerpack install instructions did mention that the sensor wires need to be moved as far away as possible from the Plug wires. I did the best I could, but I have not added any additional wiring.

 

[Bosunsmate]

Light those wet plugs- check it burns (ie no water in it). It should go pofff up in flame instantly.
Turn your flywheel to 0degs then check that your #1 cylinder is at top dead centre (ie closest point to the head)
You can do this by putting like a screwdriver through the spark plug hole and checking that the piston is changing its direction of travel at 0degs -ie it reaches full extension and then begins retracting.
And what gap are you spark testing at? It should be 7/16
Wet with fuel plugs to me indicates too much fuel or bad/ out of time spark

 

[nstocum]

Got out today and did some more testing. #1 cylinder seemed in line at top dead center. Spark Plugs are brand new and correct for the engine, so I skipped that test. Fuel burns as expected off the plugs. Checked all internal fuel lines/ Filters and there are no obstructions.

I did some electrical testing and noticed what I believe to be an indication of a bad stator. I am only getting a 4 volt peak off of the stator output when revving to 1500 RPMs ( Red lead to Orange/ Black lead to Orange/Black). The Troubleshooting guide calls for 11-24 V. If the powerpack is not getting the correct voltage from the stator, this could be the reason the timing is off, correct?

 

[racerone]

Does the spark jump a 3/8" gap or more , yes or no ?-----That would test your ignition for maximum output.-----A very worthwhile but misunderstood test !!

 

[nstocum]

It did just 3/8ths but looked very weak. Could not jump 7/16th or greater.

 

[Bosunsmate]

It did just 3/8ths but looked very weak. Could not jump 7/16th or greater.

Like i said that will cause wet sparks and your problem, go to cdielectronics.com for diagnostics