97 200HP Johnson dies under load

[jdhNC]

Hi, I have a 1997 200HP Johnson. It currently bogs down under load and dies. It will work correctly for brief periods of time and it doesn't happen at low RPM's with no load so I've never been able to replicate any symptoms in the driveway.

Due to previous problems (seemed to be fuel starved at WOT, but ran fine if the primer was pumped), I have replaced all of the fuel hoses, filters, fittings, primer, the VRO and had the carbs cleaned by a local shop. The new VRO and/or fuel fittings seem to have cured the original problem but now it dies under load. After installing the new VRO and hoses, I put it back in the water and it ran great for about 5 miles. I turned around and headed home and it started with the new symptoms.

The gas had been in there over the winter so I drained it all and refilled with fresh fuel.

Any suggestions on where to start? I already paid the shop $400 to clean the carbs, but that was before this problem cropped up. I have drained all of the fuel from the tank, put in a new water separator, a new inline filter and replaced the plugs. The plugs the dealer put in were Champions, but gapped around 0.020 if that. It really looked like they were just fresh out of the box. All six plugs were wet with some carbon buildup (looked like all had been firing at some point).

I will be checking the compression and spark in the driveway, but I have no way to replicate a real load unless I put it back in the water.
Any directions for additional diagnostics will be greatly appreciated.

Thanks,
John

 

[CharlieB]

Re: 97 200HP Johnson dies under load

Drain the carb float bowls, both sides of each carb, one at a time, pump the primer bulb a couple of strokes for each drain to flush fresh fuel. Hopefully you may only have had a couple of drops of water in one of them from the old fuel.

Now tha you have fresh fuel and a new water separator filter, if it was a poor fuel issue you should see and feel a difference.

Retest on the hose, but the only real test is to launch it.

Regap the plugs ( .028 - .032), and it never hurts to always carry a spare set on the boat.

 

[daselbee]

Re: 97 200HP Johnson dies under load

He has six individual carb bowls, not the double bowl described.
But, the same advice applies. Drain by removing the brass drain screw to make sure all water is out of the bowls.
See my response to you over on MarineEngine.com.

 

[jdhNC]

Re: 97 200HP Johnson dies under load

I checked the compression. My gauge and method gave the following:
From the back:

Port Stbd
95 95
100 100
90 95

These are almost identical to what they were when I had the motor checked when I bought it 5 years ago.
Spark looked good on all six.
I drained all the carbs and removed the jets, nothing appeared to come out when flushing them.

I'm going to try to get it down to the boat ramp tomorrow, but I'm hesitant to take it out without a lot of daylight and little ramp traffic. The last two diagnostic outings have been pretty embarassing. Any reason I couldn't leave it on the trailer and put it under load while still at the ramp?

Anyone have any suggestions for what to try with it in the water? The only things that I've really changed are dumping the carbs and re-gapping the plugs. Would the .020 gapped plugs have caused this much trouble? Would it have caused intermittent problems?

John

 

[jtcarter]

Re: 97 200HP Johnson dies under load

If you have a manual, check the link and snyc. If its fuel starvation try hitting the primer/choke on you key switch when your trying to get it to plane. If that helps it.... fuel starvation it is. If neither works, probably need to go back through those carbs looking for any peice of trash that might have gotten into a jet somewhere. Does it lean sneeze at idle? Did you use the same plugs that where gapped wrong? Probably oil fouled a couple of those. You can check spark in the drive by removing each plug wire one at a time, you should notice a drop in rpm when removed and a increase when you get the plug wire close enough to jump the gap again. Maybe something here might help you. I had a similar problem with my motor, carbs where out of sync and i had a omc mechanic put a syncronizing guage on it, fixed mine.

 

[jdhNC]

Re: 97 200HP Johnson dies under load

I have an OEM manual on the way, but nothing at the moment. I have a Clymer manual somewhere, but it has not been very helpful in the past.
Using the primer while it is running badly didn't change anything. I never had a chance to try to get on plane. When you put it in gear and attempt to accelerate, it usually dies. Sometimes it will run around 1800-2000 RPM's at WOT. When it is in this mode, it shudders alot and will sometimes rev up for a few seconds.
I cleaned and regapped the existing plugs. They only had about 30 minutes on them.
I'll evaluate the sync/link instructions when I get the manual and see if I think it is something I can handle. I will not be returning to the previous shop so I will have to find someplace else if it is beyond my comfort level.

Thanks for the pointers.
John

 

[CharlieB]

Re: 97 200HP Johnson dies under load

Good spark at cranking and idle doesn't necessarily mean that the ignition is capable of higher RPM voltage required under load.

An old trick for a failing ignition system is to reduce the spark plug gap. Since you found short gapped plugs I suspect that the shop tried to get by without testing or repairing the ignition correctly.

Download the FREE CDI Outboard Ignition Troubleshooting Guide, look up your model and start testing, follow their directions to the letter.



http://www.rapair.com/LinkClick.aspx...language=en-US

 

[jdhNC]

Re: 97 200HP Johnson dies under load

Good spark at cranking and idle doesn't necessarily mean that the ignition is capable of higher RPM voltage required under load.

An old trick for a failing ignition system is to reduce the spark plug gap. Since you found short gapped plugs I suspect that the shop tried to get by without testing or repairing the ignition correctly.

Download the FREE CDI Outboard Ignition Troubleshooting Guide, look up your model and start testing, follow their directions to the letter.



http://www.rapair.com/LinkClick.aspx...language=en-US

That seems to be a very thorough diagnostic document. The following link should work if someone else wants to see it:
http://www.rapair.com/LinkClick.aspx?fileticket=OTMbPbGaMBs=&tabid=55&mid=384&language=en-US

Thanks for the information!
John

 

[modsrx]

Re: 97 200HP Johnson dies under load

pilot jets are maybe haft way clog ... main jet are for full throttle and pilot for 0 to 1/4 throttle if choke help u have something clog in your carb ..pilot jet are little jets hole that are easy to stock **** in it ....

 

[jdhNC]

Fixed? With recap [long]

Fixed? With recap [long]

The problem seems to be fixed now. I did a lot of small things without any real intermediate testing so it could be any or all of what I will list below. It also could be that it is just temporarily running well and the problem will return. There is another oddity with the alarms that might be the real problem. I only ran the boat about 5 miles, from the boat ramp to my marina where I left it in the slip. I will try to go run it again tomorrow. The engine ran perfectly during this trip, most of the time at WOT. I think the boat is over-propped in that it will only turn up 5000rpm. I think it should top out at 5500-5800?

Since the last time it failed, I have done the following:
Checked compression, seemed OK.
Checked spark at crank and fast idle, seemed ok.
Drained carb bowls, removed and flushed high speed jets.
Verified floats and needles seem to be functional. I tilted the motor all the way up so the floats would open the needle and flushed fuel through all 6 carbs. They all looked similar. Tilted it back down and no fuel came out. Not sure if this is a valid test, but it made me feel a little better.
Regapped the plugs. Shop had them at .020-.022, I set them to .030
Replaced the ignition switch. The detents in the old switch were not solid. The key could slightly turn counterclockwise and the engine would still be running, but the accessory power would be off. More about this later.
Decarb'ed the engine, mostly following the Dunk instructions. I did this in my driveway on the hose, with neighbors close by so I did not run it very long. Used 3/4 gallon of gas and about 12 oz of sea foam. After running it for a while to get it warm, I dumped the rest of the sea foam in the cylinders and let it sit for a while. Started it back up (took a while) and started to spray some in the carbs but thought better about it. Seems like spraying straight fuel into a 2-stroke would be bad due to lack of lube? I did a little, then mixed up some with premixed fuel and sprayed it into the carbs. I noticed that spraying it in to the #1 carb would make the engine rev up higher. Spraying it in 3 and 5 made it drop down a little like it was flooded. Oddly, spraying it in to 2,4,6 didn't produce either change. Is this a sign that the two sets of carbs are not properly set to each other? I took off the #1 carb, blew it out with air and WD40 (all I had that was sprayable). I fished a few strands of copper wire through the various holes, blew through the needle valve with WD40 (while the valve was open). Put everything back together and it no longer rev'ed up when spraying fuel in the carb.
At this point, I felt that I had made some positive changes (decarb and cleaning the #1 carb) so I took it down to the ramp and tried it out on the trailer. It seemed to have plenty of power trying to drive foward on the trailer so I launched it and ran it up to the marina.

Other oddities I noticed:
Alarm horn. While sitting with the key switch turned on, but the engine not running, the alarm horn would sound periodically and the warning lights would cycle, just like when you turn the key on. I checked all the wires at the controls but no change. I pulled the power pack off and when I did, the alarm would sound/cycle when I moved it. I tried isolating each wire and wiggled/pulled/twisted and reseated all the bullet connectors, but nothing was definitive. I put the pack back on, painfully getting all the wires back in safe locations. At this point, the alarm quit cycling by itself. It would beep when the key was switched on, but the spurious beep/lights cycling seem to have quit. This bothers me because I didn't 'fix' anything unless it was one of the connectors, so I assume it will happen again.
I also checked the temp, vacuum, and low oil sensor wires. Each one would light up the correct light on the console, but the alarm did not sound. I only tried this with the key on, but not running, but surely the horn should sound anyway? I bought and installed a new ignition switch to eliminate that side being a problem since it was suspect anyway due to the flaky detents.

I want to thank everyone for their suggestions, comments and insights. Every little bit helps. I still haven't received my OEM manual so the web was pretty much all I had for reference.

Does anyone have an explanation for why the hot/vacuum/oil sensors light up but don't alarm. Or for why the alarm/lights would cycle by themselves?

Could one bad carb have caused the entire engine to be effectively useless under load?

Thanks again,
John

 

[daselbee]

Re: Fixed? With recap [long]

Re: Fixed? With recap [long]

Does anyone have an explanation for why the hot/vacuum/oil sensors light up but don't alarm. Or for why the alarm/lights would cycle by themselves?

On 1996 and up Systems Check engines, the alarm DOES NOT SOUND unless the engine is running.
So, if you turn the key on, the alarm will chirp, and the lights will cycle. Then for instance, if you ground the tan overheat sensor wire at the head, the overheat light will come on, but the alarm will not sound.
The engine must be running for the alarms to sound.
The OMC manual states "The alarm will not sound while in diagnostic mode." on page 7-36. Diagnostic mode is "key on, engine not running".

The other problem sounds exactly like the purple switched +12v line to the tach is intermittent. I think you probably fixed it when you changed the ignition switch. The powerpack has nothing to do with the Systems Check warning system.