How to create vacuum in fuel tank

My xj could only run when it was set on the "PRI" position. I noticed that it would shut off when i switched it to one. How do I fix this problem?

 

The vacuum is not in the tank but to the back of the petcock. Make sure you have a vacuum line there and that it is connected to one of the nipples on the intake boots just before the head.

If that's there and working you may need to rebuild your petcock.

 

Carlos...I had the exact same problem and incidentally the petcock just needed a rebuild. Also, like iwingameover said, make sure you have a vacuum line and not a fuel hose on your vacuum nipple. Thought it didn't matter either. Fortunately my o-ring for the fuel lever gave out which gave me a chance to order a rebuild kit. Good luck.

 

I had the reverse problem on my GPz, but still basically the same cause: sticking diaphragm in the petcock. For the GPz, I didn't need a rebuild "kit"... just a new O-ring, cleaning of parts with carb cleaner, and a bit of silicone grease during reassembly.

That's all assuming the vacuum line is hooked up correctly, not leaking, and not collapsing. If the line is leaking, or disconnected, you'll get some pretty bad performance from your engine running on 3 1/2 cylinders instead of 4.

 

Mine was running on 3 cylinders....I thought it was just the ignition coil, because at the time, unbeknownst to me, my spark plug cap came loose off of the ignition coil wire to spark plug...I can't remember it was either the number 1 or 4 cylinder off of the left coil....ha anyway I got a new coil, started it up and the one header pipe was still cold while the other 3 were red hot. I guess I have a new triple now. Had to keep the rpms up while doing anything, but getting on it in a straight away. Sorry for the ranting and hijacking.

 

petcock tech: http://xjbikes.com/Forums/viewtopic/t=25058.html

 

Hey carlos. WHAT HAPPENED?