Vector runs out of fuel @ WOT

[Metallicat]

I removed and cleaned the carbs this fall. Floats looked fine. Jets were cleaned and put back in. Had the fuel tank off and drained after having old fuel sit in it all summer.

It runs fine at all throttle positions except at sustained WOT (10+seconds) it seems like it sucks all of the fuel out of the carbs. It will lose power and die unless I back off the throttle for a few seconds.

It acts like it is running out of fuel. This only happens at full throttle on a very long run. Full throttle for shorter runs it is fine. Tank seems to be vented properly. I loosened the gas cap and it still bogged down. Seems fine running at 3/4 throttle for miles and miles.

Could clogged fuel filters in the tank cause this? Or something else? I believe the float bowls aren't filling up fast enough to keep up with the engine's fuel demand with prolonged throttle to bar usage.

 

[Srxspec]

Fuel filters, part number 8H5-24560-00-00 and you'll need 2 of them. The other thing it could be is vacuum hose going from the carb intake boot to the fuel pump, but I'd try the fuel filters first.

 

[Metallicat]

Fuel filters, part number 8H5-24560-00-00 and you'll need 2 of them. The other thing it could be is vacuum hose going from the carb intake boot to the fuel pump, but I'd try the fuel filters first.

Thank you Allen. I will check the vacuum hoses and order the filters too. At least I could still ride it this week, very thankful for that! Just no prolonged lake racing.

 

[kirkswim]

Under the needle and seat in the carburetor there is a filter screen check this and see if the screen is gummy/partially plugged. I have this happen on a bike once up to 3/4 throttle fine but full throttle over 10 sec bike would stall wait 5 sec and bike would restart. If the pumps are not pumping then it would not run on the cylinders being fed. If your in tank filters are coming apart then it would plug the screen in the carb under the floats.

 

[Metallicat]

When I had my carbs apart I did not notice any type of filter screen. What do you mean by undet the needle and seat? I've had the pilots, fuel screws, and main jets out and have had the slide valves out too. Just not sure what you are refering to.

I have new filters on order. Hoping to get them out through the filler opening. But I will take the whole tank off again if I need to.

I'll look for a pinched fuel line as well.
I just don't want it to get worse.

Rode from St. Ignace to Tequamenon on Weds and Ignace to Grand Marais on Thursday. 500 miles of mostly good trails. I'd give it a 7.5 / 10 overall.

 

[kirkswim]

With the carbs flipped upside down, if you remove the floats, then the needle and seat(these are what control to fuel flow into the carbs) under the seat part #8 in the fiche https://partstream.arinet.com/Mobil...NwebrESbGipZ3VxZAZfZnAq4LGZThJVXE_TlQI41.html

Check if there is a screen in there. When my bike did this the screen looked like it was covered in cotton, it would let the fuel flow but not fast enough to keep the bowl full at wide open throttle.

You can change the filters through the filler opening they will just fit length wise. Use a wire coat hanger to fish them out but be careful of your fuel level sensor. If I am remembering correctly when you pull the filter up you can get an inch or two of the hose out. I used special pliers that clip onto the line to stop fuel flow with a string tied to them to keep the hose from falling back in. You can use needle nose vice grips if your put rubber hose on the jaws so that they do not cut through your fuel line(just don't clamp to tight)

Change the filters in tank first to see if it gets better. If not you could unhook the fuel lines to the carbs and put them into seperate jars and see if they are pumping similar amounts (engine would have to be running) or pull the vacuum lines plug one end and try blowing into them after you coat them with soapy water. This will cause bubbles to form around the air leaks. Don't just spray soapy water onto them with motor running as it will not blow bubbles, it would actually suck the soap in to your fuel pump/intake track. Let them fully dry before reinstalling. If nothin shows through all of this then you need to look in the carbs under the floats/needle/seat.

 

[Metallicat]

Thank you for that explanation kirkswim, that helps immensely. I'll start with the filters first and inspect the vacuum lines. I had the lines off to sync the carbs recently. I have a call into Port Yamaha about filter screens in the carbs, see if they know about them. The first time my sled died at wot was one of those "oh sht" moments. Maybe it is more of an idiot fuel shutoff safety feature to tell me I'm going too fast!

 

[kirkswim]

I have never had the carbs apart for a vector so I don't know if it has the screens or not, if everything else is good then by logic it must be something in the carb that has the ability to limit or restrict fuel flow. I also noticed that you cleaned the carbs(from your original post) it is possible that you may have bumped the float/s during the process and have bent the tab out of spec so that the needle is not opening far enough to provide the fuel flow needed at wot. But you would have to have bent all 3 to have it totally cut out so I think the likelihood is small. But is is something that can be checked. I don't know what the spec is for the floats though so hopefully someone else will chime in.

 

[Metallicat]

I try not to disturb the floats at all and have never removed them when cleaning. But I've also never checked the specs on them to see if they are sitting at the appropriate height.

 

[grizztracks]

How do you properly clean the carbs without removing the floats? The floats need to come out, needle and seat cleaned then float height checked when reassembled. The carbs also should be sync'd after cleaning. If filter and hoses are good I'd pull the carbs again.

 

[Metallicat]

I changed the fuel filters this evening. That was easy, about 15 minutes to change both. Old filters looked ok. Vacuum lines and fuel lines looked good. So I pulled the carbs again and removes the float assemblies. The needle valves looked great. Two of the floats were out of spec so I adjusted them. They were 1-2mm too high @ 17-18mm. They are all even now at 16mm or close to it. We shall see how it runs now.

 

[nickleuci]

Interesting. My 06 nytro did the same thing. Happened around 75-85mph. It would bog until i backed off and slowed down then would be fine. I cleaned the carbs this year, so far so good but have not had lots of seat time.

Did not clean them last year.

 

[kirkswim]

Let us know if it solves it. Sounds like you are on the right track through.

 

[Metallicat]

Let us know if it solves it. Sounds like you are on the right track through.

There is indeed a fine mesh screen under the float valves. They are barely visible. I sprayed carb cleaner through them.

I feel like I didn't find a significant issue but maybe everything together adds up. It may have been that way for a number of years. I mean, how often do I hold it wide open at 100mph for more than 5 seconds? It took about 10 seconds to run dry at those speeds.

 

[FLRNR]

I would definitely say it was the float height. If sled runs great and only looses it after more than a few seconds at WOT, the carbs are out of gas. If you plan on doing this more often, readjust the float height to the lowest spec setting, so the floats sit higher in the bowls, allowing a little more gas for the long runs.