[24770]

I have an 02 400ex and it hasnt been running right, it seems like its starving for fuel but i cant figure out whats wrong. It had a cobra pipe on it but it broke off and I ran it w/o a pipe for a couple days and it started acting up a day before it broke off...it will run decent if i turn the choke on 1/2 way to 2/3 of the way...i can putz but if i give it probably 1/4 throttle or more it will act like it doesnt have any gas and die out and stall if i keep the throttle held down...My buddy had a stock pipe off his so we put it on mine, took the carb. apart and cleaned it thoroughly and everything was stock, jetting, needle, etc. put it back together and on the 400ex w/ stock pipe and it ran great good a new...but while i was cleaning the carb. i broke the little plastic Y piece that connects the hoses on the carb...when I ran it we put my buddies on...I took it home thinking all i had to do was get the little Y and I'd be all set...well I rode it again the next day and it ran good for a minute and then started doing the same thing...so I took the gas tank off emptied it out to see if there was any dirt, there was some but I dont know if it could even get threw the screen on the petcock, but I cleaned it all out and cleaned the petcock and blew out the fuel line...i havent put it back together yet to see how it is but....

anyone have any other idea's of what it could be?
or other things I can try to fix it?
Please help!
Thanks,
Dan
(sry its so long, just wanted to give all the details)

 

[24770]

anyone have any idea's???

 

[28551]

well about the pipes stay away from cobras they are cheap for a reason

it sounds like your main jet keeps getting clogged
be shure your air filter is on correctly and that its clean

get a feul filter that goes on the gas line after the petcock to collect dirt from that if its still a problem

give me more info and i will try to help you out

 

[24770]

I got rid of that pipe because it broke and got a stock one from my buddy cheap so Ive got that on it, the carb has stock jetting and everything else. I ended up taring the carb apart, didn't really find anything, but tore it completely apart cleaned it and put it back on, it ran great that day, the next day I went and rode it for about 5 minutes and it started doing the same thing. So I tore the carb apart again and found a chunk of something on the end of the jett and in the bowl, it looked like chew. So again I cleaned it good. I also took the tank off, and dumped it into a gas can and used paper towel as a filter to see if there was junk in my tank, there was some but nothing that looked like what was in my carb. I flushed the tank out good, and took the petcock off the tank and cleaned that up, blew out the gas line and then put it all back together. Again, it ran great for a couple days and then started doing the same thing AGAIN! Took the carb apart for a 3rd time, samething, it looked like someone took their chew and put pieces of it in the bowl of the carb. so i cleaned it again along with the tank (which was clean) and the petcock. I filled the four wheeler up at the gas station w/ premium and ive rode it once and its been fine. I just dont understand where this stuff is coming from, my air filter is clean, my air box is clean.

Any ideas are greatly appreciated!

 

[28551]

ok soo we know that it is the main jet getting clogged. now we need to find where the dirt (chew) is comeing from.

hmm very weird
u should (just to be extra safe) put a fuel filter (like 3-5 bucks) on ur gas line right after is comes out of the petcock.

u say your air filter is clean. well make shure that it is not falling apart from the inside (it will disolve if its old and worn) (just go buy a new uni air filter if it is)
another i have found on my 400ex is that the crank breather hose that connects to the intake boot right after the filter might be loose or off. then letting dirt in the boot right pass the air filter (if ther is a random hole on the side of the intake boot that is where your crank breather hose should be)

the chew like stuff might be mice getting in your quad some how (you would be surprised) and bringing some stuff with them and then it gets sucked in with gas and looks moist like chew. also check to see if they are getting your filter and chewing that.

if u still are getting stuff in your main jet then mabey some rubber hose from a feul line is disolveing and small chunks are getting in there. (replace any worn hose lines)
after that i really dont know. keep me informed because id like to know whats the deal lol

 

[24770]

I have been thinking about the fuel filter, but would that restrict it from getting enough gas to the gas since it doesnt usually have a fuel filter on it?

I know the air filter is clean, I took it off, checked it all out, washed it real good and everything and put it back on. Where exactly is the crank breather hose located?

Im pretty sure there aren't any mice getting into it. It is always stored inside and there is a ton of activity in the shed its stored in. I also, mess around with it or ride it dang near every weekend.

I have looked at the fuel line as well, it looks good as new, no cracks, or debris in it, not deteriorated at all. There is one hose on the carb, I think its just a overflow, not the one on the bottom of the bowl, but its got 2 that come out of the carb and go into the Y piece and then one comes off of that and i think its an overflow for incase you flip the quad. But anyways one of those little hoses has a little crack where it slides onto the little Y piece.

This is definitely a tough one. I really appreciate your help.

Thanks,
Dan

 

[28551]

oh no the filter WILL NOT in no way restrict the gas flow at all unless it is filled with debris (easy to see most are made with clear plastic)and if it is filled that means u got dirt in your tank somehow. i run a filter on my 400ex my buddys banshee. and all the mashines i have ever owned (quite a few)

as for the over flow hoses dont worry about those u dont even need them they just direct the gas off your engine if your needle vavle is leaking. but its still good to replce the damaged ones if u have gas line around.
oh be shure to oil your filter with air filter oil or the dirt will have nothing to stick to and go right through. whitch will result in a dirty carb if u ride in dusty conditions. remember every filter (even K&N)must be oiled (other than paper filters found in cars and some polaris's)


your crank breather is found one end up in the intake hose (big black rubbery plastic boot after filter) it goes in right on the side so that the crank has clean air to breath. and the other end is below the carburator going in the cases to the crank (if the hose is not secured to the bottem point u would notice oil splatter and im shuire u would notice if it was disconnected) but with the 400ex it has a white plastic "bubble" or chamber before going into the intake boot. if u notice its not hooked on the small hole or not there then thats your problem (imshure u can see pics on google) i have it come off every once and a while with mine.

 

[24770]

Ok. this weekend I bought a piece of fuel line and a filter but I have not put them on yet. I also checked my crank breather...looks fine...no cracks, its clean...and attached correctly.

I didn't really get a chance to ride it much this weekend but for the short time I did, it ran great.

i will let you know when i put the new line and filter on and whether or not it stays running good or if it clogs again.

 

[28551]

ok sounds good
glad to help

 

[24770]

So far it has been great. I haven't had anymore clogging of the carb (knock on wood). I bought a fuel filter and new fuel line for it but I'm only going to put them on if I have more trouble. Well, maybe the new fuel line but not the filter till more problems...
Thanks for the help

 

[24770]

For some reason now it seems like it doesnt get enough fuel when I start it up when its cold. I rolls over alot longer than it used to. But when its warm and I turn it off and start it again it fires right up. Could this be my pilot jet partially clogged or what?

 

[28551]

well with the new cold weather of winter it will do that

when u use the choke does it help?

also before u start cranking it over , push the throttle a few times because the 400ex has an accelerator pump and it will squirt a little gas in the intake everytime u hit the throttle (this helps for throttle response) but just holding down the throttle wont do it

if those both dont solve the cold starts than, idk cause u say once its warm it starts right away so i dont think its your pilot

after i replied to this (this is an edit) i went to go fire my 400ex up
i dont have the choke in so there is less resistence. i had to push the throttle a good 20 times before it fired up

all carburated quads will have a little tuffer time starting in the cold.

 

[24770]

yeah, I know that. The only thing is though, last year I don't remember it doing this. I mean its not bad, it starts and goes fine so. But I was just curious.

Honda's have always been cold blooded machines...