Help with carb problem

[QuadRacer041]

A freind of mine has an 04 yfz. It sat all winter and when he took it out for a quick spin last week it started up and idled fine. He went up his block and then it just died and he couldnt restart it. It cranked but wouldnt turn over. So he brought it over to my house yesterday and we messed around with it a little bit. I pulled the air filter off, and sprayed some carb cleaner in there while hit tried to start it and it kicked over. So i pulled the 17mm plug off the bottom of the bowl and no fuel come out. By the way we checked and it DOES have spark. When i saw there was no fuel in the bowl i thought i had it figured out, he had a problem last season after the quad sat for a while where the needle for the float froze. So pulled the carb and sure enough it was frozen. I freed it up put i back together and tried to start it. It would only start if i held the throttle open slightly. As soon as i let go of the throttle it would die. If i try to rev it up i back fires sometimes. I took carb back off and cleaned inside the bowl cover as best as i could. I took the jets out, spray carb cleaner, blew air through, etc.... I put it back together and the same thing...starts only when you hold the throttle open, back fires sometimes when you rev it and as soon as you let go of the throttle it shuts righ off.
Any ideas? Think it is still a carb problem?or could something have happened where the timing chain jumped? He said when it shut off it didnt make any strange noise or anything, just stalled.

[CTmxyfz]

i had a problem like that with my red bike last year. It would not idle. It ended up beaing that stupid tps or whatever it is. The wires that ran to the stock thumb throttle. We cut em, spliced em, and it ran fine after that. Before, we had to hold it open some so it would run like you have to now.

[QuadRacer041]

did yours back fire too

[CTmxyfz]

Yes it back fired and would not idle. It was the throttle position sensor. 2 wires that ran into the throttle. Their is a clip that clips togegher. Disconnect it and if it runs like normal then splice them together.

[QuadRacer041]

Originally posted by CTmxyfz
Yes it back fired and would not idle. It was the throttle position sensor. 2 wires that ran into the throttle. Their is a clip that clips togegher. Disconnect it and if it runs like normal then splice them together.


thats not the tps, the tps is on the other side of the carb that has the 2 plugs comming off it that plug into the wirehareness. your talking about the saftey micro switch i think. its just a saftey feature.
i will try it and see what happens.
thanks justin

[SRH]

nooo tors not tps, leave the tps alone tors= throttle over ride system, tie those ytogether and try it...possible when something froze in the carb it cracked???

[brink400]

Try the needle valve. It is the little thing that is connected to the floats and it regulates the fuel coming into the float bowl. I have had 2 separeate yfzs that have had the needle valve stick from sitting there all winter. Just take the float bowl off and pull the actual floats out and loosen up the needle valve and reinstall everything. Its quite simple to fix but it took me forever and a day to diagnose the problem both times i had it.

[CTmxyfz]

Originally posted by QuadRacer041
thats not the tps, the tps is on the other side of the carb that has the 2 plugs comming off it that plug into the wirehareness. your talking about the saftey micro switch i think. its just a saftey feature.
i will try it and see what happens.
thanks justin


I'm sorry you are correct. The wires in question come right into the throttle.

[CTmxyfz]

First post was from me(justin) the rest was pa dukes:D

[QuadRacer041]

Originally posted by brink400
Try the needle valve. It is the little thing that is connected to the floats and it regulates the fuel coming into the float bowl. I have had 2 separeate yfzs that have had the needle valve stick from sitting there all winter. Just take the float bowl off and pull the actual floats out and loosen up the needle valve and reinstall everything. Its quite simple to fix but it took me forever and a day to diagnose the problem both times i had it.


yea he had that problem before so that was the first thing i checked. Thats was part of the problem.

[QuadRacer041]

Ok,
Here is where it stands, lol. I think its ok now. When I removed the carb the other day cleaned and put it back in we tried to start it but had forgot to plug in the TPS plugs. Thtas when it started but wouldnt idle and was back firing. We shut it off and pluged them in as soon as we saw that they were unpluged but it still ran the same. So what we did was disconnected the battery until the next day when my freind tried disconnecting the TORS. He called me and said it started right up and ran and idled fine. So I told him(just out of curiousity) to reconnect the TORS and see what happens. Sure enough it was fine.
Is it possable that trying to start it with out the TPS connected threw them or something else out of wack even after plugging them back in? And disconnecting the battery reset everything? Kind of what you do with a car to reset the computer.
One thing I would like to mention is he did this all last night when it was dark out. When it started back up and was running fine he said that the head pipe was glowing red????? I know this means a lean condition but is it possable that its always been like this and he only noticed it because it was dark outside?

[mountaineer]

It is normal. The first day I bought mine that night I went for a ride and the head pipe glowed cherry red thought I was making a horse shoe:eek2: