Gas Tank Vacuum Sealed?

Your talking about the purge valve that's part of the evap system correct? Has the electrical connection?
Yes, it sits directly below the canister. It has a line on both ends (one going to the three throttle bodies and one to the canister), with an electrical connector on one side. It shuttles open and close to pull stored fuel vapor from the charcoal canister and is controlled by the engine management system. The canister also has another vacuum line from the #3 throttle body that controls the outlet line to the fuel purge valve via an internal vacuum switch. It opens when you start the bike and stays open while running. My thought is if the fuel purge valve is stuck open, the throttle bodies will pull excessive vacuum in the tank, once you shut down, the canister internal valve closes and keeps the tank in vacuum. If you are not keen into blowing through the valve, try running the bike until you build up vacuum, then unplug the line from the canister side of the fuel purge valve and it should relieve the vacuum. The bike must be running as the internal vacuum switch must be open.
 
well i am going to take an educated guess at this problem. because most evap systems return the fuel and burn it i suspect there is a defective evap system so the vacuum of the engine is sucking through the evap system and then the tank.
u might try to find the vacuum line going from engine to the evap and temporary disconnect and plug it for test purposes.
 
well i am going to take an educated guess at this problem. because most evap systems return the fuel and burn it i suspect there is a defective evap system so the vacuum of the engine is sucking through the evap system and then the tank.
u might try to find the vacuum line going from engine to the evap and temporary disconnect and plug it for test purposes.
Yeah, thanks. My plan was to remove the whole thing anyway so this just give me even more reason.
 
leatal explained it much better than me.
also it might be interesting to see how long the engine has to be off before the vacuum goes away on the tank. for example 30 seconds or 10 minutes.
 
leatal explained it much better than me.
also it might be interesting to see how long the engine has to be off before the vacuum goes away on the tank. for example 30 seconds or 10 minutes.
This time my bike sat 10 hours and I remembered to check it before I rode home and that's when it was sealed shut. But as I said earlier, I could tell it was running off a little like the first time I noticed it so that was in my head to check the tank again.
 
leatal explained it much better than me.
also it might be interesting to see how long the engine has to be off before the vacuum goes away on the tank. for example 30 seconds or 10 minutes.
I would think the vacuum would not go away unless you had a leak in filler neck seal or one of the lines. The vacuum switch inside the canister opens and closes from suction in #3 throttle body- no suction, switch closes, system remains as set at shutdown. Your best bet is pull all that junk off, cap the throttle bodies and enjoy. UNLESS Delaware has a method of checking the emissions.
 
i was just thinking that if it was broke it might release the vacuum but i guess not.
 
I would think the vacuum would not go away unless you had a leak in filler neck seal or one of the lines. The vacuum switch inside the canister opens and closes from suction in #3 throttle body- no suction, switch closes, system remains as set at shutdown. Your best bet is pull all that junk off, cap the throttle bodies and enjoy. UNLESS Delaware has a method of checking the emissions.
I'm good without all that emissions crap in Delaware. I was actually surprised to see all the emissions stuff on the bike when I started looking into this problem.
 
I would think the vacuum would not go away unless you had a leak in filler neck seal or one of the lines. The vacuum switch inside the canister opens and closes from suction in #3 throttle body- no suction, switch closes, system remains as set at shutdown. Your best bet is pull all that junk off, cap the throttle bodies and enjoy. UNLESS Delaware has a method of checking the emissions.
I just studied my canister. I think the fuel tank is always vented to the outside ambient air through the canister. The fuel tank vent line goes through the rollover valve into the right side of the canister, then out (or in, depending on which has higher pressure) through the large vent line on left side of the canister. The canister prevents fuel vapor from escaping by the use of the charcoal discs and the trapped fuel vapor is recovered back to the engine as explained above. That give us two areas of concern. The big vent hose on the left side of the canister may have something blocking it (remove it and check for insect nests) or the canister may be clogged up preventing it to vent. So your problem probably will not be the valves, rather problem with canister not venting to the outside air.
 
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I just studied my canister. I think the fuel tank is always vented to the outside ambient air through the canister. The large hose on the left side of the canister is the vent hose. The canister prevents fuel vapor from escaping by the use of the charcoal discs and the trapped fuel vapor is recovered back to the engine as explained above. That give us two areas of concern. The big vent hose on the left side of the canister may have something blocking it (remove it and check for insect nests) or the canister may be clogged up preventing it to vent. So your problem probably will not be the valves, rather problem with canister venting.
Thanks Leatal!!
 
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