Running problem at idle --on the road

[markmartin]

Hi all,
Well, I'm half way through an epic trip through Virginia, to Memphis and now I'm in Chattanooga, and headed to Asheville in the morning.  The FJ has been running fine until this morning.

It is intermittently cutting off and dying at idle. It'll then start right up and if I keep it revved up, it will run and then runs fine at highway speed,( although I think it sputtered a couple of times at speed)  It will go back to idling just fine and running well like nothing ever happened,  then all of a sudden it will die at idle--just drops off and dies.

I ran sea foam through two tank fulls since it started acting up this morning.
I also stopped at an Autozone parts store and checked the battery--12.8 V off.  13.1 V at idle and 13.8 V at 3-4000 RPM.
I installed a new fuel filter in Chattanooga this afternoon but I'm still getting the issue.
I changed the fuel pump about 1500 miles ago.  Carbs have been balanced, and new plugs installed this spring.


Does anyone have any ideas to what is causing this drop off to dead at idle?

Thanks

Mark M

[FJmonkey]

It dying suddenly and only at idle does not sound like a fuel issue. Air and Fire (spark) are the two possibilities left. Check the air filter, it is easy to check and will cost nothing. If the filter seems fine then you have an electrical/ignition issue.

[Flynt]

It dying suddenly and only at idle does not sound like a fuel issue. Air and Fire (spark) are the two possibilities left. Check the air filter, it is easy to check and will cost nothing. If the filter seems fine then you have an electrical/ignition issue.

I'm betting electrical...  have you cycled the kill switch?  Sounds like a vibration inducted "kill" signal is most likely cause.

Frank

[aviationfred]

I am going to agree with Frank..... Sounds electrical.

I checked my voltage with a warm engine. 13v @ 1100 rpms and 14.5v @ 2000 rpms and holds steady all the way up the rev range.

The Haynes manual states with an unloaded engine, rpm at 5000 should be 14.2v-14.8v. Loaded engine 14v @ 5000 rpm.

Could be a battery or charging issue.


Fred

[FJ_Hooligan]

Possibly a bad coil?

[simi_ed]

This sound a bit like Capn Ron's ignition problem he had on The Great Adventure a few years ago.  
Ron, care to chime in?

Ed

[Firehawk068]

This also sounds like the gremlin that Erich V had with his '84 on our way up to Willits in 2010.
It ended up that his kill-switch was the issue.
Corrosion, or faulty connection here will give you a bunch of headaches.

[oldktmdude]

   Replace the spark plugs before you do anything major. Not uncommon for plugs to act up and cause bad running at low revs.
Also a cheap place to start trouble shooting. May not be the problem but it's a good place to start.
                                                                                                                                              Regards, Pete. 

[markmartin]

Thanks for all the quick responses.  I'm going to check my air filter and cycle the kill switch then head out to Asheville.  If it continues, I'll try to service the kill switch.  I'll keep checking this site through the day.

thanks guys!

[fj1289]

   Replace the spark plugs before you do anything major. Not uncommon for plugs to act up and cause bad running at low revs.
Also a cheap place to start trouble shooting. May not be the problem but it's a good place to start.
                                                                                                                                              Regards, Pete. 

+1 on the plugs.  I was taught early on (and relearned the lesson when I've ignored it) that spark plugs are "consumables" for motorcycle engines.   I've had several "ignition", "electrical", or even "fuel" issues cleared up with a new set of plugs. 

Good old "basic" NGK's - no need to spend a lot of $$$ on platinum or multiple this or that. 

Of course, if that doesn't work - try draining the float bowls - you may have picked up some water in a bad tank of gas.   

[markmartin]

Thanks for he input.  Monkey Mark, I checked my air filter first thing this morning.  No problem there but definitely was worth looking into.

I changed the plugs with a new set of NGK's this spring.  Found and fixed a bad wire from the generator a few weeks ago also...thought I had my problems licked.  Oh well, I'm still suspicious of my kill switch and have never service it--I'm hesitant to open a can of worms if I service it in the parking lot, never have been in the switch.

I turned the idle up this morning to mask the problem, but it's still there--it wants to cut out every once in a while when I'm at idle--once in a great while at speed.

I've got my old (functioning) fuel pump being shipped to me when I get to Charlottesville , Va on Monday afternoon.  I'm guessing it's electrical with the way it just cuts off and the input from the FJ brethren but, I'll eliminate my the fuel supply theory when I get the old fuel pump re- installed.

That said, we made Asheville today and are headed to Blacksburg VA via the Blue Ridge parkway tomorrow.   It's beautiful country.  You folks in Tennessee, NC, and Virginia are very lucky.  I'll be posting a trip report in the next few weeks.

Again, thanks for the input and advice.  It helps!!

[Pat Conlon]

Hey Mark, sorry to hear you're having problems on your trip. Intermittent electrical problems are maddening.

I agree with the others re: stop/run switch on the handle bar....but (what I found) it could be anywhere in that circuit, not necessarily the switch itself. This circuit (which runs through the run/stop switch) supplies the 12v power to your ignightor box. The start of the circuit is the fuse box, through the key switch, through the run/stop switch and then down to the ignightor.

I checked the wiring diagram for your '89 and you have a red wire/white stripe that supplies power to your ignightor. Try running a temporary jumper wire from the + side of your battery or if your worried about fuse protection, run the jumper from a switched side of the fuse block....skin back the original wire's insulation and terminate this jumper wire on the red/white stripe wire about 2" from the plug at the ignightor.

Could it be a bad ground? It could. The same can be done on the (negative) grounding side. Run a jumper from the - side of the battery to the black wire at the plug. The black wires on the FJ are always the grounded conductor.

This will assure you that your ignition is getting a full 12 volts with no interruption or guessing.

Hope this helps. Pat

[JPaganel]

Try this. It's only 6 inches of wire, real cheap an easy. It's the red one (yes, I know it should be black) from the negative terminal to frame.



This cured intermittent no-starts and weak spark by providing a solid ground to battery.

[Sabre093]

I was just in Deals Gap and hat 2-3 occasions where my bike died and happen when i was rolling out...I'm going to watch this thread closely...I thought my problem was due to the monsoons i got caught in.

[markmartin]

We made it back to the truck yesterday safe and sound.  Aside from the bike intermittently dropping off and dying at idle, it ran perfectly.  I'm going to investigate the issue when I get back home.  I'll be checking the kill switch first and then other connections including grounds.   I've got to learn more about the ignitor and how to test it.  Also how to test the coils.. ??