Check Valves / Back flow preventers?

[BTexLBJ]

1985 Ski Nautique 2001....Question: is there a back flow / check valve in between the gas tank and the hose connected to the input to the gas filter / water separator?
I tried to blow through it to no avail...like zero. So either its very clogged or there is a back flow valve. TIA

[NautiqueJeff]

Yes, there is likely an anti-siphon valve. They are usually right by the gas tank.

[BTexLBJ]

Thanks. Any experience with how to ensure I’m getting good flow without taking out the tank or getting to that valve?

[bturner]

Draw a vacuum on the line and see if you can get fuel flow. Whatever you do don't remove the valve without putting another in. See my posts on boat fires for my reasoning on this topic.....

[BTexLBJ]

Thank you bturner.