1999 Johnson 200, erratic RPM

[Cricket Too]

I have twin Johnson 200's on my boat. The starboard motor runs fine and I have no problems with it. The port motor runs fine at idle and does not miss, but at about 3700 rpm when i'm planed off every now and then this motor will all of a sudden kick up to about 41 or 4200 rpm for anywhere from 30 seconds to a minute and then go back down to 3700 where it was before. Also I tried using each motor by itself to get on plane and the starboard motor will do it, the port motor struggles and I can't get the speed out of it. Someone told me it is because the port motor is a counter rotating motor and it will always run lower rpm's but I don't but that, beacuse I can get the revs out of it when it decides to kick up. Any help on where to start troubleshooting would be appreciated.

 

[Hooty]

Re: 1999 Johnson 200, erratic RPM

I think you have a cylinder in the port engine that's not firing. Occasionally, when the engine goes up too 41 - 4200rpm is when that cylinder does fires. Could be something easy like a loose sparkplug wire but my guess is it's an ignition breakdown somewhere.<br /><br />c/6<br /><br />Hooty

 

[Cricket Too]

Re: 1999 Johnson 200, erratic RPM

Hooty... wouldn't that also cause either hard starting or rough idle? Because this motor does neither.

 

[ob]

Re: 1999 Johnson 200, erratic RPM

There are several issues including intermittent spark loss that could cause the symptoms you describe.I tend to feel that you have one or more caburetors on that engine that have fuel restrictions in the fixed orifices or porting.The only way to be sure is to remove and clean each carb.Probably a good idea to install new kits.Was this power loss a sudden occurrence or had boat not been run for a spell?

 

[Cricket Too]

Re: 1999 Johnson 200, erratic RPM

ob...no, the boat gets run every weekend without fail. It has been doing this all season though, and since I just bought the boat this season I don't know if it was doing this for the previous owner. I was thinking carbs also, because it starts very easily, even after sitting all week, and idles very smoothly. It is just every now and then under way when I am criusing that it does this and it also won't open up as much as my starboard motor. Most likely the carbs have never been decarbed or rebuilt so I guess it is about time anyway, I'll give that a shot and hopefully it will work. Thanks.

 

[ob]

Re: 1999 Johnson 200, erratic RPM

mmcpeck,If you have a reputable dealer nearby have him connect a dynomometer to that engine and run it up under load to insure you are not experiencing spark problems.Do all of the sparkplugs on that engine look consistent in color and oil wetness?

 

[Cricket Too]

Re: 1999 Johnson 200, erratic RPM

ob...I will check the plugs and let you know what they look like. As for the dealer idea it's pretty good. I have a very good Johnrude dealer right by me and I will check if they have a dyno. I think I'm gonna try some decarb and see if I get any noticeable results. Thanks.

 

[Hooty]

Re: 1999 Johnson 200, erratic RPM

I once ran my V6 for two weeks with a sparkplug wire off and didn't know it until I pulled the cowl off. I was proping at the time and knew something was hookie but I thought I just couldn't spin the props I was trying. <br /><br />c/6<br /><br />Hooty

 

[Cricket Too]

Re: 1999 Johnson 200, erratic RPM

Hooty....I will definetely try looking at those wires first, it would be nice if that was the problem. There's no sense in looking for anything else if you don't look at the easy fixes first. Thanks.

 

[Hooty]

Re: 1999 Johnson 200, erratic RPM

Check the wires but you can also use a timing light on each different wire to be sure each one is firing. A non-contact thermometer, (the one with the laser pointer) will also tell you which cylinder is not firing by the low temperature of the sparkplug.<br /><br />c/6<br /><br />Hooty

 

[pdspeh]

Re: 1999 Johnson 200, erratic RPM

hi, I also experienced a similar problem...w/ my 2001 70 Evinrude( Suzuki)...wouldn't go full , kept bakin' doen...changed all the spark plugs...fixed...like you said ...start with the simple things...<br /><br />where on LI are u?

 

[Cricket Too]

Re: 1999 Johnson 200, erratic RPM

Hooty...where would I get one of those non contact thermometers from, just any automotive store or marine store?

 

[Cricket Too]

Re: 1999 Johnson 200, erratic RPM

pdspeh....I am from Stony Brook as well small world huh. <br /><br />P.S. What is an Evinrude(Suzuki)? Those are two different engines.

 

[Hooty]

Re: 1999 Johnson 200, erratic RPM

NAPA has one for about $80. One of the handiest tools in my box. <br /><br />c/6<br /><br />Hooty

 

[Cricket Too]

Re: 1999 Johnson 200, erratic RPM

Hooty....Tried your timing light idea and it worked like a charm. Found my bottom right cylinder getting no spark at idle and then when you rev it up a little bit it starts firing but fires spiratically then dies when you go back to idle. Checked the ignition coil to see if it was loose and maybe not grounded good, but it was nice and tight so I'm gonna switch it with another coil and see if the problem moves to a different cylinder, then I will know it is the coil. Thanks for the help, I really appreciate it.

 

[Hooty]

Re: 1999 Johnson 200, erratic RPM

Por nada.<br />Keep us posted.<br /><br />c/6<br /><br />Hooty

 

[Cricket Too]

Re: 1999 Johnson 200, erratic RPM

Hooty....Switched the coil from the dead cylinder with the one right above it that I know is working, and nothing changed. I still have the same cylinder getting no spark even with a coil that I know is good. Tried swithcing the wires and that didn't work either. <br /><br /> Talked to a local Johnnyrude mechanic that I know is good and he suggested that the next logical step would be to check the power pack and he also suggested that since I have twin 200's I should just swap the power pack from the motor with no problem rather than buy one from him and not be able to return it if it was not the problem. So I did that and that didn't work either. I swapped the power packs and both motors run exactly the same as before, starboard no problem at all, and port still has that same one dead cylinder.<br /><br />I'm running out of ideas here and really don't want to take it to him, I have not looked into any of the sensors yet because I believe that would affect more than one cylinder. Someone also mentined that the magnets sometimes move under the flywheel and that the stator could go bad, but I also doubt that this would only affect one cylinder and I can see that the magnets have not moved. Any other suggetsions that could help would be appreciated, from anybody out there, so that I don't have to pay this guy 90 bucks and hour in labor to pull this thing down and figure it out. Thanks.

 

[Bluefish]

Re: 1999 Johnson 200, erratic RPM

I assume when you said you switched wires you talking about the ignition wires, did you do both in and out of coil? Under the boots there not that great of a setup just a spring, that pierces wire. In addition, try running temporary trigger and ground wires you could have a bad our corroded connection at the crimp.

 

[Cricket Too]

Re: 1999 Johnson 200, erratic RPM

Bluefish....Thanks for the respnose, but I replaced the entire power pack so that takes care of the trigger wire and as for ground, the coil is grounded directly to the block with a clip and through the bolt that holds it on so there is no wire for ground. Thanks.

 

[Cricket Too]

Re: 1999 Johnson 200, erratic RPM