I have a 2004 DVX 400 Has been an awesome machine far greater than my last machine (87) Yamaha Warrior. Wow what a difference, anyway i rode it for a while until i was comfortable with it and since then jetted it with a dynojet stage 1 jet kit, i have the stock air filter but have a pro circuit t4 slip on. It runs killa but recently i couldnt get it started and then the battery when dead/shot so i brought the limp kitty to a local bike shop and let him check it out, (i put a new battery in it before i brought it to him) he started it in PRI and warmed it up and said it was good to go..Well its not, it will run in pri and dies in the on postion. There is a line off of the petcock (right side that goes to no where!! at least that is how i found it? The left side obviously goes to the carb1!! 1. Is this line supposed to go to something? 2. Is the petcock clogged? 3 Is there a screen in that thing? 4. or is it something entirely different? Any help would be greatly appreciated. Riding with the North Quabbin Gang in Central Massachusetts Boyeee

 

Well i think it could be your Spark Plugs or your wiring in it, But so far my DVX is great i seen this happen to people before..

 

Not sure I follow you on that one, It starts every time in "pri" or 'on" but if it is left in "on" it dies due to lack of gas, I'm sure it only runs on the residual fuel that is left. I dont think it is a spark plug issue.

 

when my brother got his 04 DVX we wentout riding and his died after screwing around he switched it to pri and ot started rode for a little bite swiched it back to run and hasnt had a problem with it sence.
I remember a post here awhile back on this

 

I don't know why Suzuki has stuck with the "Prime" and "Run" type petcock, seems redundant to me, the Pri, or Prime position,lets fuel flow directly to the carb, just like all the regular "on/off" type petcock, while the "Run" will only pull fuel when the engine is running, using vacuum from the carb to pull in the fuel, possibly some kind of safety valve set up to prevent fuel from running into the carb in case of a needle and seat failure. I would check all your hoses, chances are one that goes to the carb vacuum is off or pinched, and not pulling fuel into your carb. Not having seen a DVX up close, I can't say where to look.

 

I had the same issue on my Eiger. I added a clear fuel filter after I rebuilt the carb. After starting it in thr pri position, I switched it to on. After riding 30 or so minutes it died. I repeated the process, pri, then on and it shortly died again. I now run it in the prime position. Question: does the vacuum line from the petcock connect to the vacuum port on the carb?

 

If I had to guess I'd say the problem is in the petcock.....

There is a known issue with the z400 where the petcock itself gets clogged, so it will only run on PRI ...... I've heard people take them apart and there was debris in the petcock that was stopping the gas from flowing. Which is why it runs fine on PRI.

 

I have a 04 z400 and I have to run it on prime all the time.

 

I haven't worked on an atv like yours but what 95wolv says sounds right or the petcock itself could be clogged. On older model Suzuki 250s they have the petcock with the off- on-pri settings. The petcock has a fuel line to the fuel pump and a fuel line out of the pump to the carb. There is also a vacuum line from the petcock(right side) and the fuel pump to a carb suction port. When the motor isn't running a diaphram shuts off fuel so the crankcase will not fill with fuel if the needle doesn't seat. The pri setting lets fuel bypass the diaphram and gravity flow to the fuel pump for cold starting. Hope this helps.