Hi Everyone, I have an 01 LT80 Quadsport that has been sitting for about 1 year. I replaced the petcock valve because it was "stuck" (would not rotate to different positions). My problem is I can't get gas to flow to the carb. Seems like a "vacuum" issue. With petcock set to ON and I manually suck on the vacuum line connected to petcock valve, gas will flow from petcock to carb. However, when I try to start the ATV I get no gas flow through petcock valve.
I have since replaced the carb as it was pretty "gunked" up when I removed it. Still no gas flow. My question is should I have gas flow just by setting the petcock to PRI position? Or, do you still need to pull a vacuum? Any suggestions greatly appreciated.

 

You should have flow when set to prime, that is what it is for, however, no big deal if it doesn't, as you should be getting flow when on run, but it takes a while to fill the bowl. I recently did the main bearings on one which has this problem and just sucked the vac tube, held this for 30 seconds and then put the tube on the carb. Once started the vac in the inlet manifold provides the vacuum. Are you sure you put the pipe on the right carb fitting? Manifold side for vac pipe airbox side for breather pipe.

 

I disconnected the gas pipe from petcock to carb and left the vacuum pipe connected to petcock. When I try to start the ATV shouldn't I have gas flow out of petcock (gas pipe side)? My carb connections - The below pic I have vac pipe (black arrow), gas pipe (red arrow), beather pipe (green arrow). Correct?

 

The above picture is correct, but if you get flow when you suck the vac pipe you will get flow with engine running, but may not when just spinning on the starter. Fill the carb, get the bike running and take the fuel pipe off, my bet is it will be flowing freely.

I did get Chinese petcocks for a couple of LT80s and found the pri, run, res markings did not correspond with reality, had to mark the correct ones in white paint on the tank. May be worth experimenting with which position really is which, if you have been buying a Chinese cheapo petcock.