03 Viper High Idle and Backfiring

Find your TPS on your carbs follow the wire back their should be a two connectors disconnect and reconnect the wires together that lead into the harness and not the one on the carbs. This bypasses the TPS system so now you can determine if this is your problem or not . When it is active it will not let the machine rev past about 3000 so the primary can not engage. Just had to replace my ol lady's on her rx1 sounds very similar to what happened to hers.
 
Sorry that's the tors my bad! Just Google tps and will find step by step by step. My brain isn't working and have you the wrong info. But sure sounds like tps to me
 
So I called the old yammie dealership that pointed me to my viper years ago. As I told them manager what was happen in he said that he knew what I meant as he's heard them do that before. He was leaning toward my tps as well. He also pointed out that when I adjusted my fuel screws closer to 2 turns than just 1-7/8 turns I actually leaned it out not richened it up. So.... Off came the carbs again. Adjusted them between 1-3/4 and 1-7/8 turns and put them back on. Tors was bypassed. Got it running....still no change. It won't idle right. Keeps climbing. Even the last few times it was idling right it would begin to slowly climb toward 3k rpm and hang for a few seconds and come back down. If i full choke it, it dies, if I half choke it then the rpms climb, turn choke off and it dies. He was thinking that the tps was.starting to go and therefore advancing the cdi. Even if I do get another tps I can't find info on the tps specifically and just keep finding info on the tors which is fine on my sled. Would be great if I was a matter of take off and put on like my old pick up truck but i dont think the viper works like that.
 
I'm probably going to pull the carbs again either today or tomorrow as that seems to be the only thing I can really do short of having electrical pigtails for testing the tps and such.

after i cleaned the pilot circuit again a few times ago it idled good but with a little stumble. The stumble may have been simply from a fuel screw being just off from the others but now once again it wont idle for beans again. Im going to go through the circuit again but really what could be clogging up the pilots after they are cleaned? Not much fuel line length or room in there to pump some fuel into some baby food jars or the like but I think that's something I will have to attempt. It also bugs me that I can choke it and it climbs in the rpm range instead of dying down like its always done in the past.
 
Grimmy said:
So I called the old yammie dealership that pointed me to my viper years ago. As I told them manager what was happen in he said that he knew what I meant as he's heard them do that before. He was leaning toward my tps as well. He also pointed out that when I adjusted my fuel screws closer to 2 turns than just 1-7/8 turns I actually leaned it out not richened it up. So.... Off came the carbs again. Adjusted them between 1-3/4 and 1-7/8 turns and put them back on. Tors was bypassed. Got it running....still no change. It won't idle right. Keeps climbing. Even the last few times it was idling right it would begin to slowly climb toward 3k rpm and hang for a few seconds and come back down. If i full choke it, it dies, if I half choke it then the rpms climb, turn choke off and it dies. He was thinking that the tps was.starting to go and therefore advancing the cdi. Even if I do get another tps I can't find info on the tps specifically and just keep finding info on the tors which is fine on my sled. Would be great if I was a matter of take off and put on like my old pick up truck but i dont think the viper works like that.
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let me just say the guy who told you that you leaned out the fuel screws by moving them to 2 turns instead of 1 7/8 is highly mistaken!

You can go all the way out to 2 1/4 turns with tthe stock screws but they dont have much tension on the screws on them to keep from falling out but it would tell you real quick if thats your issue.
 
Grimmy said:
I'm probably going to pull the carbs again either today or tomorrow as that seems to be the only thing I can really do short of having electrical pigtails for testing the tps and such.

after i cleaned the pilot circuit again a few times ago it idled good but with a little stumble. The stumble may have been simply from a fuel screw being just off from the others but now once again it wont idle for beans again. Im going to go through the circuit again but really what could be clogging up the pilots after they are cleaned? Not much fuel line length or room in there to pump some fuel into some baby food jars or the like but I think that's something I will have to attempt. It also bugs me that I can choke it and it climbs in the rpm range instead of dying down like its always done in the past.
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While you should be able to clean the pilot circuit as Mr Viper suggests, I have had stuborn deposits that would not come out without backflushing or using 90 psi compressed air.

I would suggest the following: pull the carbs, bowls and pilot jets. Take the straw that comes with the carb cleaner and twist it around a pencil once. This will bend the straw into a 90 degree elbow which will allow easier positioning of the straw.

Then position the carbs as they would sit as installed on the sled and place a clean rag under them. Now find the tiny hole just in front (towards the engine) of the needle/jet main and place the cleaner straw at it. Make sure to wear eye protection and spray some cleaner into the hole. You should be able to see a good stream of cleaner leaving the hole that the pilot screws into. Inspect the rag for the culprit. See the photo below.

Another possible issue is an air leak at the carb boots given that your symptom seems to change when removing the carbs.

Finally, I'd suggest finding another dealer... or at least bypass the service manager and go right to the tech... unless he's under the age of 25. Your TPS may or not be faulty, but it isn't causing your idle issues nor is your fuel pump.
 

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Yah, I would be leery of a service guy that doesn't know the TM carbs have fuel screws instead of air screws like the VM carbs. The TY advice above is very good advice. This is one of the reasons why most of us don't take our sleds to dealers for any kind of service.

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This is why I became a VIP member of this site. Love being a part of such information flow and knowledge base.

Im going to be taking the carbs off again and going thru them as I stated earlier. I will also be using my air compressor to clear any passages. I thought of the air leak as well but couldn't find any when spraying carb cleaner around the boots.

After reading through various posts/forums, I thought it may help to put the screws between 1-7/8 and 2 turns, as I would rather be slightly rich than lean. In lieu of that I did think it was odd I was being told that I was leaning it out by going out to 2 turns. Remote fuel screws and heat in my garage...2 more things to add to the wish list. :-) Thank you all
 
OK, with carbs off and all jets out..... when I spray cleaner into the brass slotted orifice in the airbox side of the carb, through the main jet location, etc... where should the spray be coming out of? Whenever I spray cleaner in any of the orifices it comes out thru multiple places in the carb. Is the flow of the cleaner modified only when some jets are in their respective locations?

the question is in regards to the following...
2.) while the pilot jets are out, do or did you squirt some carb clean or brake clean up into where the pilot jet threads in and it comes out the throat in the idle orfice hole in the FRONT side of the carb?

and what is the "idle orifice hole?" the orifice with the brass piece in it or the hole next to it?
 
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Grimmy said:
OK, with carbs off and all jets out..... when I spray cleaner into the brass slotted orifice in the airbox side of the carb, through the main jet location, etc... where should the spray be coming out of? Whenever I spray cleaner in any of the orifices it comes out thru multiple places in the carb. Is the flow of the cleaner modified only when some jets are in their respective locations?

the question is in regards to the following...
2.) while the pilot jets are out, do or did you squirt some carb clean or brake clean up into where the pilot jet threads in and it comes out the throat in the idle orfice hole in the FRONT side of the carb?

and what is the "idle orifice hole?" the orifice with the brass piece in it or the hole next to it?
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the small idle orfice is in front of the brass nozzle, the cleaner needs to come out of the orfice in the bare aluminum, it should not come out of the brass nozzle.
 
i would like to backflow compressed air through the circuit so I am wondering if I should have all the jets in with the exception of the pilot and then feed air in to blow out whatever may be in there. In doing so, put main jets and fuel screws back in then ??? Should I be trying to blow air into the hole in the aluminum nest to that brass piece in the back of the carb or blow it through the pilot jet loaction and hope it blows out the bare aluminum hole?
 
on a side note, oddly enough, when your response came through to my email on my phone there was an extra sentance on that message that wasnt included in the post on the site. about that being where my problem is in your opinion.

I know my jets themselves are as clean as they can be and everything else is fairly consistent in it's behavior to be a low speed issue.....reading through various posts of yours and others throughout the forums regarding high idling and carbs I'm seeing what you are with regards to the prob being in those carbs. Just not sure why whatever it is isn't coming out, but it will!
 
The pilot circuit, starter circuit and main circuit are all separate. Of course they all get fuel from the bowl. Just clean each circuit separately. I would be surprised if your main or starter circuits are plugged, so I would just focus on the pilot circuit. Basically air in the opening in the air horn, fuel from the bowl through the pilot jet these 2 connect with passages to the venturi (under and just behind the slide). All are connected and need to be free from any debris. Some carbs don't have the orifice under the slide, but I think the TM carbs still do. Don't have one in front of me but Don would know for sure. Anyhow I would just zero in on the pilot circuit. Also make sure the pilot jet tower is not cracked or otherwise compromised.

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mrviper700 said:
the small idle orfice is in front of the brass nozzle, the cleaner needs to come out of the orfice in the bare aluminum, it should not come out of the brass nozzle.
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I dont get this... The air hole in the back of the carb...airbox side....has a small brass piece in it and a hole next to it that is countersunk but goes nowhere and there's a larger hole at the top of the carb. I can't remove that brass piece I'm referring to so I dont know what u mean by in from of the brass nozzle
 
same sled. my sled was doing very similar issues, IT WAS till now, melted right side piston on lake half throtle. Im guessing were sucking air in from some where. will be folllowing this thread. my carbs were clean
 
I think I may pick up some new boots from airbox to carbs and some new clamps. When I blew out the carbs with air a sliver of white came out of one f the carbs. It was some paint that came off a golf tee I was using as a plug... Note to self...use plastic tees as plugs, not painted. Otherwise, these carbs r clean as can be. I certainly dont need air leaks. Besides the carb boots I can't think of any other place air would be getting in. Once I get these carbs back on and get it running, I'll c f I can find any leaks.
 
The pic in my previous post doesn't show exactly where the cleaner straw is being located (I only had two hands and one was holding the camera). Just behind the main jet nozzle (the brass tube the needle slides up and down in) is the tiny pilot orifice (engine side of the needle). With the pilot jet removed, spraying through the tiny pilot orifice should show a good stream of cleaner out of where the pilot screws into. Cleaner will also flow out of the fuel screw hole if the screw isn't in place. In the pic, I did manage to get cleaner flowing out of the pilot jet hole even with one hand and I also have the throttle wired open. While not as common, spray around the PTO crank seal as well as the boots which are also not very common... on a Yamaha that is.
 
I saw the stream coming out the bottom when sprayed through that orifice. When MrViper700 responded with what he did, I presumed he was referring to the front of the carb at the air jet not the inside of the throat which is why that threw me. I went through the carbs last night and cant find any obstructions. While shining a flashlight through the front of the carb (with throttle wide open) I can see light just fine through the pilot jet orifice on all three and spray comes out where the pilot jet threads into as well. Ill get them back on the sled this afternoon and see if I can get it fired up. Im also going to see if I can pick up 3 new boots and 6 clamps.....boots from airbox to carbs and all clamps necessary for front and back of carbs. Some of the clamps are stripped a bit and on one of the boots, I did just fins a small tear underneath where the clamp rests....i think that area would technically be the outside of the carb so I dont see that being where a leak would come from. I was going to be replacing them this summer anyway, might as well do it now to assist with piece of mind.
 
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