it just dies after an hour of seat time -- help!!

[huffdaddy_400EX]

OK. this is weird. I have a 2004 z400. The only mods are yoshi full exhaust, KN filter, EHS airbox lid. The problem is that after about an hour of riding the quad dies. It sort of acts like its out of gas ( have half a tank). When I try to restart it it won't. If I let it sit for 5 minutes, it starts. So I thought with that mentioned that it might be over heating. But the coolant level is fine. I checked the thermostat and all the sensors and they check out. The fan is fine too.

Has anyone ever had the same issue? Any thoughts on where to look? This is driving me nuts!!!!

[bradrenea]

Could possibly be something in the electrical system starting to go out. (stator, rev box, coil) I have had it happen in cars before. An electric component was going out and it would only act up after the vehicle was warm and sitting while running for a while. The heat build up under the hood was causing the part to get hot and then it would fail. After it cooled off it was fine. It was a booger to find it since I would always wait for it to cool off to test everything, and then it would test fine.
May be a long shot, but I thought I would throw it out there.:(

[ex kid]

check for dirt in the carb and fuel tank. alot of times when dirt is in either the machine will run for a few mins then shut off once the dirt is stirred up.

[bradrenea]

in reference to my reply above, I just remebered that the same thing happened a while back on a honda trx200 that I was working on. Finally figured out that the cdi box was failing after it got warm. Replaced it and the problem was fixed.

[huffdaddy_400EX]

I'll check the CDI. The carb and fuel tank are ok. The quad will run fine for 45-60 minutes. Power is fine. Then, without warning, the power goes away...like it is running out of gas....then it just dies. The motor will turn but not fire. If I let it sit for a few minutes it will start right back up and run fine. It's the craziest thing. I've never had an issue like this with my ex.

[bwamos]

After checking the CDI.. make sure non of the screws/bolts backed out of your stator plate. Happens more often than you'd think. ;) Especially if you've worked on the stator. It causes the stator to loose it's ground.

[huffdaddy_400EX]

I'll check the screws, but I haven't worked on anything in that area. Thanks for the info

[underpowered]

sounds dumb, but check the gas tank vent hose and make sure it isnt clogged. i have had one on a polaris melt shut and cause the same prblem. it would run fine for about an hour and then the vacume in the tank was too much and it would shut down, let it sit and release vacume and it would run again.

[huffdaddy_400EX]

interesting....I did replace the old hose not too long ago...I'll check that too. Thanks

[wilkin250r]

Ok, so it dies after 45 minutes, and won't start right away.

You let it sit for 5 minutes, and it starts.

What happens after that? Do you get another 45 minutes out of it? Or does it die after 5-10 minutes?

[huffdaddy_400EX]

I took it out over the weekand and rode for an hour straight. I was on an MX track going down into a tight turn. The motor sputtered, I gave it a little gas, it sputtered more and then died. It felt like I ran out of gas. I coasted off the track, checked the gas, it was fine. Checked the fuel switch to makes sure it was in the ON position...it was. I tried to start it and it cranked but did not fire. I tried 3-4 more times and nothing. I check the plug, the battery...all fine. I got back on and it cranked right up. I rode it back to the truck (3/4mile away), checked it over and found nothing wrong. I let it sit maybe 10 minutes and then went out again. I guess I was out maybe 30-45 minutes and it did it again. I had just came off a trail and it sputtered and died. I tried 3-4 times and nothing. I sat there a few minutes and it started right up. I then went back to the truck and packed up. This is criving me nuts...everything "seems" ok...but something isn't!!!

[bradrenea]

When it would not start, did you check to see if it had spark? That needs to be determined to know if it is electrical ot fuel. If it does not have spark, then your going to have to test everything when it is acting up or you'll never find it. If you have a riding buddy that as the same bike you can swap CDI's and go riding and see if you still have the problem or he does. That's how I finally figured out the problem on the trx200. I had a buddy with one and I snagged it and started swapping parts. I had checked everything with the multimeter but it was not when it was hot so the problem would not show up.

[duke416ex]

Have you taken the fuel hose off the carb when it dies to see if fuel is coming out, thought it might be the tank vent hose.

[huffdaddy_400EX]

Originally posted by bradrenea
When it would not start, did you check to see if it had spark? That needs to be determined to know if it is electrical ot fuel. If it does not have spark, then your going to have to test everything when it is acting up or you'll never find it. If you have a riding buddy that as the same bike you can swap CDI's and go riding and see if you still have the problem or he does. That's how I finally figured out the problem on the trx200. I had a buddy with one and I snagged it and started swapping parts. I had checked everything with the multimeter but it was not when it was hot so the problem would not show up.

I'm the only one on a Z. I did not check the plug because it didn't seem like that was the issue. I can check it if ( or when ) it happens again

[huffdaddy_400EX]

Originally posted by duke416ex
Have you taken the fuel hose off the carb when it dies to see if fuel is coming out, thought it might be the tank vent hose.

No, I am a little scared about taking the hose off so close to a "hot" motor (fire fire!!!). It might be the vent hose, as I mentioned early in the thread, it was replaced very recently.

[huffdaddy_400EX]

I swapped out the CDI, replaced the fuel vent hose, emptied the fuel tank and added fresh gas (checked for dirt and debris inside...none), checked the stator was secure, cleaned the air filter, pulled the card apart and cleaned it.....too a long nap :D

Then took it out...and guess what...it is still happening...what the $#!$#!!!!!!!!!

It was 53 minutes into it...I was in 3rd and it just sputtered and died. :grr:

[bradrenea]

When it died, did you check to see if it had spark?

[huffdaddy_400EX]

forgot to add that to the list, yes I did....and i also checked the wiring, and kill switch. Looks like I am going to need to strip it down and go peice by peice. :scary:

[wilkin250r]

Ok, here is my thoughts.

It runs for an hour, dies, you let it sit for 5 minutes, and it runs again.

If it runs again for another hour, the problem is fuel-related. Somehow, your gas tank can't keep up with fuel flow. Either your vent hose, gas cap, petcock, fuel line, or fuel intake on your carb is messed up. That 5 minutes gives it enough time to equalize pressure and run for another hour.

If it you start it up after 5 minutes, and it only runs for another 10 minutes, the problem is HEAT related. CDI, coil, stator, even your spark plug wire, possibly even your regulator.

[bradrenea]

Well, did it have spark?

[huffdaddy_400EX]

Originally posted by bradrenea
Well, did it have spark?

yes

[huffdaddy_400EX]

Originally posted by wilkin250r
Ok, here is my thoughts.

It runs for an hour, dies, you let it sit for 5 minutes, and it runs again.

If it runs again for another hour, the problem is fuel-related. Somehow, your gas tank can't keep up with fuel flow. Either your vent hose, gas cap, petcock, fuel line, or fuel intake on your carb is messed up. That 5 minutes gives it enough time to equalize pressure and run for another hour.

If it you start it up after 5 minutes, and it only runs for another 10 minutes, the problem is HEAT related. CDI, coil, stator, even your spark plug wire, possibly even your regulator.

I was sort of leaning towards the fuel system myself. I plan on taking the fuel system part tonight.

[huffdaddy_400EX]

OK...this is weird.

I removed the fuel tank and cleaned it, change the oil and filter, pull off all the electrical and cleaned the connections, and flushed the radiator. I took it out over the weekend and it ran fine, no issue. I ran for 2 hours staight and it never died or even sputtered.

One of those did it...but I have not idea which on...oh well...at least it works now!! :D