Fj 1200 stalling at stops

[stroscoach]

I recently purchased a 1986 fj 1200 rode for a week no probs today it stalled at a light while I was trying to take off, tried to restart no turn over pushed to parkin lot jump started rode 2 miles cut out while riding this time would turn over but wouldnt start . loaded on truck got it back home put charger on battery cranked it over started right up let battery charge for 2 hrs went for a ride ran great for twenty minutes came to light and could feel it starting to break up stalled at light turned over wouldn't start tried reserve started. felt like it was breaking down under slight acceleration on the way back . It doesn't do it at every stop and runs very well most of the time. carbs recently rebuilt . any help would be greatly appreciated

[WestOzFJ]

Well if it were me I'd be suspecting either a fuel blockage or some other fault at the vacuum operated fuel tap.

Perhaps the plastic gauze like filter on the valve that sits inside the tank is partially plugged, or the tap is not opening fully/correctly - the diaphram in the valve may be split/perished and leaking vacuum or the fuel cap is not venting correctly and not allowing air in to the tank to displace the fuel useage.

Try running it with the cap un-latched, try attaching a length of small diameter vacuum hose to the small connection port on the valve and suck on the tube - simulating vacuum from the cylinder opening the valve - fuel should run out of the tap's fuel outlet. If you can't hold a vacuum on that little hose, the diaphram is unserviceable.


Interesting little thing about that valve...

In 1985 a Japanese reality TV show got 25 motorcycle engineers onto the show who each proceeded to drink 2 bottles of Sake' and then they had to design and build their best idea whilst the other contestants shot beebee gun pellets at each others' genitalia.

The winner was the guy who invented this valve.....

[andyb]

...no turn over...

Electrical.

[Dan Filetti]

I'm with Andy.  Sounds electrical. 

How long are you running before this happens, how long are you sitting at the light?  Does it stall all at once, or sputter some before stalling?  Do you get the sense that it would start again if you just wait a bit?  If you can get it going, does it get better one moving?  Do you know what running on less than 4 cylinders sounds like?  Does it sound like that at all? 

I ask because for my '85, it my would start to cough, and choke, and sputter when sitting at a light for more than say 45 seconds, but really only after it was hot enough.  It turned out to be a bad coil, that when sitting at a light, the engine heat would radiate up, and the coil would fail.  It would start right up for me though. Maybe yours is closer to catastrophic failure?

It can be tested fairly simply with a timing light shined against the spinning rotor as it shoes the symptoms.

Then again, it could be something entirely different.  Be patient, you'll solve it.

Dan

[TRoy]

replace battery 

[stroscoach]

Thanks everyone for your imput at first I thought electrical because the first time it happened it would not turn over and started with a jump after the jump i only got a few miles down the road and it quit while is was moving felt like like i was loosing electrical power as I riding it stalled and it wouldnt turn over at first while I was waiting to be rescued I tried several times to start it was now turning over but wouldnt start. after charging the battery I tested the alt output an at idle I get battery voltage but as I rev it goes up to 14.5 volts.  I test drove after that and it ran good for twenty min then as i was coming to a light I could feel It starting to break down when I got to the light it stalled would turn over but wouldnt start I pulled the choke up a bit hit the reserve and it fired up rode it aprox 3 mile home .  took tank off check petcock for debris looked clean seems to have good fuel flow found a bad conection at battery repaired that went for a test ride ran great for 6 blocks stalled at first light had to pull choke up for it to restart. As for the pet cock can I run the bike on the prime setting? Thanks again

[Marsh White]

After reading everything - I think WestOZ has the right idea when he said it may be a gas cap venting problem.  You never said that you tried what he said - try riding with the gas cap cracked open.  At least rule that out.

Your battery is probably screwed up too - could be a combination of both.  A new battery is cheap at Wal-Mart - $35 or so...

[andyb]

+1

More than one thing is probably wrong here.  Start with a known good battery.  If it's cranking slow when hot, you'll need to R&R the starter as well.

The other problem with it trying to die after it's good and warm could be a bunch of things, but the gas cap deciding not to vent is a common problem and an easy fix, so start there on that.

[stroscoach]

Hey guys I may have solved my problem (fingers crossed ) I noticed my fuel gauge  is not working properly and I read somewhere most likely here that this could cause some running issues so I unplugged the gauge and went for a ride rode for an hour with no problems . What do you all think?