'00 2.5L 150 Merc Missing check-valves?

[scyc]

I'm doing an overhaul for the spring on my '00 150 Carb'd Merc, (#0T145971), new reeds, carb kits, bleed hoses, etc... Pretty much the entire fuel system.
I noticed when looking at a parts diagram for my motor, that it's supposed to contain the check valves... but mine are missing??

I've read here about what the bleed lines do, and how the check-valves work, but are the valves really necessary? My motor seemingly runs fine without them (sometimes).

I also saw a post where someone mentioned rerouting the bleed lines back into the main fuel tank? Is is worth it?

I do idle a lot and it does seem to flood once in a while when trying to start it back up sometimes.. but I'm thinking it could also be a myriad of other things going wrong with my fuel system.

I don't mind installing them since they're not that expensive.

Thoughts, ideas?

Thanks in advance!

[TEXAS20225]

the check valves are the bleed line bibs themselves they only work one way , if you have bleed lines then you most likely have check valves its the little nipple where the line plugs in to the block (6 of them 3 each side) try blowing and sucking on one of them, you just dont know it, people who need to reroute fuel to tank are the efi boys that are either horn motor or laser with vst removed and fuel pump is in the boat, your carbs probaly need a good cleaning or rebuilt or it could be a need of an experienced carb man adjusting them