Bike shut down--then ran fine.

'85 XJ700N-- after about 8 miles the bike began to act like it was starving for fuel and as I turned it the station it died. While rolling into the station I tried to start it a couple of times and it would start and then shut down, again like it was starving. Then it wouldn't start at all. Opened the cap but decided to try to get it home and see what was going on. Then it started and ran fine all the way home. I'm thinking a collapsing vacuum line, a plugged vent, or even a vapor lock. Last week I ran 12o miles with not issues. The gas cap was disassembled, cleaned and checked several months ago. I have an inline filter situated vertically, although the gas line always has a bubble of air in it. I have a thick fuel line installed as a vacuum hose. (I compared the vacuum hose and fuel line before I bought the line and the fuel line was much more difficult to compress than the vacuum line.) Is there a simple way to test the cap for venting and the vacuum line for collapsing? Any other suggestions. The bike starts instantly, runs great, and gets good mpg.

 

Plugged cap vent is my first thought.

 

^ +1

 

Can you guys post a picture or a link to where the plugged cap vent would be? I might be having the same problem.

 

did you buy gas at the station ? How much?
clean out the cap again to eliminate it as a problem.

when I had an air bubble in line i set to prime and it gets drawn into the tank.
make sure your clamps are tight

 

how about a link on fixing it
Your Gas Cap and You

 

I'm going to go through the gas cap again, but I shouldn't need a complete tear down just to check the vent, should I. I didn't add any gas--since I decided that I would go ahead and remove the tank and work on a small dent.

 

I don't think so -- as you can see from the writeup, two screws to take off the latch assembly/bottom plate, and the ball valve is accessible. Dump the ball out (if it even moves), and shoot some cleaner or poke a wire down the hole.

 

I think I accidentally discovered this same issue by having the not-so-clever idea of painting the gas cap black to match some other components. Nothing highlights ignorance of how something works better than a simple aesthetic upgrade (spray paint) that renders your bike unable to run (clogged vent). D'oh!