VENT LINE CHECK VALVE circuit

[BC3]

to help me understand....on a 97 xp

a properly functioning vent line check valve allows air INTO the gas tank but not out so that the tank will be allowed to be slightly pressurized to allow positive fuel flow to the supply lines (a closed loop if you will) If that check valve fails (as mine seems to be under a test)...would it weaken the fuel delivery system(?) How would this faulty check valve show under a running condition?

Also - re- the vent drain on the port side..is that supposed to vent easily under normal pressure (i.e. it doesnt vent when I blow into the line, but will if I use an air gun nozzle). On my stand ups..the inlet hose goes to a drainable water seperator tank. I am assuming that this just an external water drain and yet I can NOT blow through it. Isnt that just going to hold water in the line? Is it servicable? Thanks bc3

 

[seadoosnipe]

Cleaning........

It's time for you to go through your tank lines (hoping they are not grey) and clean them out.

YOu should have no pressure build up on that tank, none what so ever. The fuel pump of the carb moves fuel and returns it to the tank. If there is pressure on that tank, your carbs will have a problem functioning properly.............:cheers:

 

[BC3]

so.. the check valve lets air in, but it IS NOT working properly (it also lets air in the opposite direction- hence not doing its job)

I am replacing all lines etc now and found that this ck valve appearts defective..is that going to cause any problem?

 

[Dennis]

Check Valves

There are two ckeck valves for your fuel tank. There is one that let's air into the tank but not out. The other one is a pressure relief valve. It let's pressure out but not air in. The "pop off'' pressure of this valve is approx 1.5 psi . That explains why you needed air pressure to get air thru the valve. No air should be allowed to go the other way( into tank ). That is the other valves job. I'm not sure but I can see these valves causing running problems if defective. If the one valve fails to open it could cause your fuel tank to come under a vacuum and that could cause fuel starvation to the carbs. If the pressure valve would not release pressure then the tank could over pressurize causing carb problems and possible fuel leaks.
DAWG