troubles with starting

[Striker]

Hey guys my 85 FJ1100 has quite suddenly developed an issue starting for me. She started up just fine to head to work yesterday. And shortly after work it started raining.  But she has had to be in the rain before and started fine so didn't worry to much. There is no covered parking at my work so no way to prevent being in rain. Anyway when I went out to start her she turns over just fine but refuses to light up. I was able to get a buddy of mine to come help me and by putting a little RC plane fuel in the line (has nitro) and a bit of working the throttle was finally able to get her started. While moving forward and keeping rpm's high at stops she did ok. I almost when I got home i let the rpm's drop a little to much I guess for a turn and she just died and would not start at all. So had to push it the rest of the way home. (i know long explanation) The battery is fine but engine won't light. It was suggested that it might be fouled plugs. So will change those. I am curious though as to what else it could be. Any suggestions or help would be appreciated immensely! Ideas that come to mind are fuel issue either in petcock or fuel line. Or it has something to do with the carbs, coils or plug wires. I am not sure where to start after plugs. So am in need of the collective experiences with this bike. I love it and this is the first major mechanical issue I've had with her. Thanks in advance for any help!

[Striker]

Oh and yes I did think of the fact it getting wet may have done something electrical to it. But it has been drying in my garage for a day now and no improvement in starting.

[fintip]

We've had a ton of rain (for Texas standards, anyways) combined with cold since the new year, and my bike is my only form of transportation, so I've gotten some experience starting it in cold/wet weather recently.

Short answer: the bike just doesn't seem to like moist air, as far as I can tell. It's really a bitch to start it in the cold+wet. The only time I absolutely couldn't get it started is when it was actively raining, and cold.

As far as it dying when you let the RPM's drop... Was it fully warmed up (how far is it from work to house?), and did you still have the choke on at all? Other than that, I am reminded of an issue that XJ's used to experience in rain, which is the coil housings getting cracked. Moisture gets in there, and then it won't fire and will just die. Later, when it dries out, it will be fine and show no symptoms. A test is to cover the coils with a plastic bag, and then spray the bike with a hose while the bike is running. Verify no effect. Then take the bag off and see if that kills it.

Don't know if these bikes ever have that problems, but more than one XJ developed it.

If I knew I'd have to deal with rain on a regular basis, I'd probably keep a can of starter fluid handy. Combustion engines are just air igniters, with a little gas to facilitate. It's really hard to get wet air to explode.

And new spark plugs can't hurt; I hadn't changed my spark plugs since I got the bike until just yesterday, for what it's worth. (Mine weren't fouled or malfunctioning, but there was some rust developing on the outside of them). That being said, I doubt they're fouled from wet weather.

Edit: Re: Electrical: When you press the starter button, it is trying to turn over, just not spark, right? Assuming so, have you pulled out a spark plug and verified that you have spark?

[Arnie]

Your bike is 28? years old.  Over the years you've probably gathered a bit of dust and grime under the tank.  Doesn't matter much while its dry, but if it gets wet that dust and grime becomes an electrically CONDUCTIVE paste.  Plus, it is also likely that your spark plug leads are original and may have dried and cracked insulation.
This has allowed a lower resistance pathway for your hi-voltage spark signal to get to ground than through your plugs.  There may or may not be a visible spark if you take the tank off and try to start the bike in the dark.
Check for carbon tracking on the coils and all along the spark plug leads.
Replace your spark plug leads if you find any cracking in the insulation.
Wipe all the hi-tension bits (coils and spark plug leads and boots) with alcohol, or acetone, or even gasolene.
Replacing the spark plugs may help as when new the resistance is lower AND the porcelain is clean.

Arnie 

[Arnie]

One other thing that may be the cause of your weak spark with rain conditions.
One or more of the connectors somewhere in the ignition circuit may be corroded. 
Pull them apart and re-connect each a couple of times.  That'll clean them.  If you want, you can also put some "dielectric grease" on the connector pins so it doesn't happen again soon.

Arnie

[RichBaker]

We've also had reports of the various "black boxes" filling with water... Might be worth pulling the ignition box apart.

[Pat Conlon]

The bike is pissed at you....leaving her out in the rain like that...tsk, tsk..

[FJmonkey]

I can second that, my beloved is kept under a bike cover year round in SoCal. Not proper but all I can do for now. But I use quality grade covers, not that cheap ass stuff of a single layer of nylon fabric. But I have been making more room in the garage even when struck with the nasty flu going around.

Corey, how soon are you gonna have your (RPM upgraded) forks on and getting your Kookaloo on? We need a ride report on your upgraded FJ...

[Striker]

Hey there thanks so much for the advice! I checked the plugs leads and coils, and seem to be ok. No cracks or carbon tracking. (side note how hard is it to replace those with upgraded ones?) I took out the uni filter and it was pretty moist from a bit of water seeping in a little, let that dry. May have been part of problem as stated can't ignite moist air. Took a heat gun on lowest setting and a good distance away and with tank off used that to dry connections and wires. Then miracle of all miracles she started!  Now starts and runs normally. I agree she was a little upset with me for how I treated her. So we had a talk (i will be getting a good cover) and she seems to be a little happier...  Though still a little cranky with me. Because now there is other issue. She starts and runs but now my headlight and dash lights don't come on.    All other lights work, just not headlight and lights that illuminate gauges. Check headlight fuse- good. If I remember those are connected to ignition switch so first thought is take that apart and clean contacts in case water caused issue there as well. Any other thoughts as to where to look or what might cause this problem? Thanks again guys! This forum has always been very helpful! 

[fintip]

Yeah, if the ignition switch isn't lined up just right (like isn't pulling out all the way), then the circuit for lighting up the dash and headlight will stay open. That was what I first thought of too. Pretty simple to pull apart and troubleshoot with a small jumper wire or such.

[Arnie]

What Kyle means when he says "ignition switch" is START switch.
Pretty sure the dash and gauges lights are on the "SIGNALS" fuse.

Arnie

[Dads_FJ]

My bike had issues starting in the rain or when wet.  That is until I replaced the plug wires and caps, that stopped the problem for me.  I inserted the new wires into the coils and used silicon to seal them up.  When I worked at a garage, we used to trouble shoot ignition problems with lights dimmed, shorts would light up like a thunder storm in the dark, much easier to see! 

[fintip]

What Kyle means when he says "ignition switch" is START switch.
Pretty sure the dash and gauges lights are on the "SIGNALS" fuse.

Arnie

Correct.

[RichBaker]

Starter switch gets gunked up with old lube and sticks in a bit. Pull out on the end and you'll know for sure. It's easy to take apart, clean and relube. I used white lithium.