engine sputtering in the rain

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not2shabby

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The last couple of days it's been coming down pretty hard when I left for work and it's sputtered when I get it some gas. Not wot, just normal keep up with traffic stuff. Yesterday I stopped and filled up thinking it might have a little moisture in the tank and it was on reserve. Went out at lunch and she ran fine, and on the way home it was good, but it wasn't raining. This morning...rain again...pretty hard, but nothing you can't ride in, and she's sputtering again. Anybody else have this happen? Think a shot of Seafoam will cure it, or is something electrical getting wet and shorting?

 
I had something like you're describing on a thumper I once owned, and it turned out to be the 'kill switch'. When it rained the kill switch was getting water in it, causing the bike to stumble or die... Just a thought.

 
I had something like you're describing on a thumper I once owned, and it turned out to be the 'kill switch'. When it rained the kill switch was getting water in it, causing the bike to stumble or die... Just a thought.
Interesting...I'm gonna give it some Seafoam when I get home from work. I went out for lunch a few hours ago and it was still raining (Ohio weather has sucked this spring!) and it wasn't as bad. If that doesn't work, I'll check out the kill switch...if that's not it, maybe the plug wires are next. Joy...

 
Odd. First I have ever heard of an FJR having any issues operating in the wet.

Damn POS Gen IIs!

 
I've ridden my GenII in the rain for a couple of hours and the only thing that really sputtered was the rider....

 
Hover your mouse pointer over any dotted underlined word.

The problem is almost certainly electrical. It is unusual for water to affect low voltage circuits (12 volts) but water can cause havoc with high voltage circuits -- think coils, plug wires and plug caps. It is very characteristic of high voltage problems to cause rough running and stalling at low rpm but let the engine run acceptably at higher rpms. This could be a difficult problem to track down.

Plug wires can crack, plug boots can get torn and coils do crack. When that happens the high voltage will jump from the defect to ground, bypassing the spark plug. One thing you can try is fairly easy. Raise the tank, take off the heat blanket, remove the rubber shield under the Tee bar (my Gen I has a rubber shield, dunno about the Gen II) and expose the valve cover. Inspect what you can see and reach, look for cracks and chaffing at wire contact points. Check that the plug caps are firmly attached and look for damage to boots. Find/buy a spray bottle that can make a fine mist. In the dark, with the engine running, use the bottle to mist the plugs, plug wires leading to the coils and the coils. If any of the high voltage components have a problem you will almost always see lightning bolts. Unfortunately, the way the coils attach it is possible for a coil to 'leak' high voltage to ground without your being able to see it. In any case, when you mist an area and cause an arc you should notice the engine speed or engine smoothness to change. Spraying one area at a time will help pinpoint the problem.

 
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S4 is in a bad place for wet weather riding. It sits right there in the air flow coming in around the steering head. In addition to what Alan has suggested, I'd take a close look at that connector.

 
S4 is in a bad place for wet weather riding. It sits right there in the air flow coming in around the steering head. In addition to what Alan has suggested, I'd take a close look at that connector.
Yes, for sure. It's low voltage but it is part of a known systemic problem. Great input Dan!

 
Not2,

Other than what was stated above, check out your Coil Tangs as seen here to see if they are not bent to a shorting position:

https://www.fjrforum.com/forum//index.php?showtopic=126721&view=findpost&p=714281

Also, while I was looking for electrical/intermittent gremlins, I went through all the Wires (and Spark Plug Wires) and cut Rubber Hoses as Insulators at All Areas where the Wires were Touching Metal areas. This is when I ended up Finding the Main Harness Connector and found the contamination in the Contacts... yours may be in the Spider Connectors.

Good Luck with your fix....

 
There have been a lot of great suggestions so far, but I'd start with the spark plug boots, ignition wires and coil boots. Thankfully the conditions are easy to reproduce. Get a spray bottle and get the high voltage ignition system wet. Odds are good that that is where the problem lies. If not, keep getting things wet until the problem surfaces.

Joe

 
Well, this morning it was raining much lighter and no stumbling was noticed. Guess I'd better look under the hood before I find myself sitting by the side of the road in the rain somewhere...Thanks for all the input!

 
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