I have a 2003 LTZ400 I was riding the other day and all of a sudden the ATV cut off and would not crank back up, I took a fuel line loose and turned the gas to fuel on and no fuel came out the line, I then turned it to Reserve, again no fuel came out, but when I turned it to Prime fuel came running out, whatever this could be is definitely causing my ATV not to run, I was thinking maybe something is clogging the fuel line or something I really have no Idea, and would greatly appreciate any help. Thanks

 

I really think this is a petcock issue. drain the tank pull the petcock off and see if the screen or intakes are plugged. Seth 03

 

I second seth03 idea lol

 

The petcock will not flow fuel unless it is in the prime position. There is a diaphram in the carb that sucks the gas from the tank. When the petcok is in the on position fuel will only come out when the carb "asks" for it. This is why the Z carb does not have an "off" position. On is off (sort of).
I think you need to look elsewhere......sounds like the petcock is not your issue.

 

darn new fangled quads lol why cant every one just buy a 1987 lt500r the QUADZILLA haha

 

hmm! any new ideas then? lol! I appreciate the input from everybody!!

 

spark?

 

Thats a good idea lol I've had the ATV for a lil over a year now and haven't changed the plug yet maybe i'll try that thanks

 

I had actually typed out more then just spark not sure where it went. You may want to check the CDI. If you have access to another, known to work CDI, you could plug it in to see if that does the trick.

 

my son Z400 petcock was always on prime thats the only position that fuel would come out in. finally got rid of both of the junks the petcock and vacuum carb glad to have them off so much more power with an edelbrock carb on