offthefront

the outlets for the fuel lines have check Valves ... could that be an issue going from 365 to 600 hp ? I assume they are there to keep the pickups primed. Mechanical fuel pumps .. ......m

MOBILEMERCMAN

Those are anti syphon valves. It is intended to keep fuel from running out of the tank if fuel line to motor leaks. Boats are required to use them to get coast guard certification. The are responsible for flow problems when you modify your motors. 600 hp should have 1/2 inch fuel lines. If you remove that valve it should be replaced with a shut off valve.
Jim

tobin

Can these valves go bad? I have had trouble with my pump being able to pull the gas from the tank to the pump to the carb. I think this check valve has left me floating around one too many times. I wonder if they come in different strengths?

When I pulled mine off, I could barely get any air through the correct way, no less backwards. So I wonder, if I can't get air through the proper way, how can my pump pull gas through when it needs it?

I have done no motor mods (besides changing the mechanical fuel pump with an electric one) and for some reason the mechanical, and electric one had trouble pulling gas from the tank to the carb.

thoughts?

MOBILEMERCMAN

Well they are there for safety, they are not the greatest thing for a motor to deal with. They don't really go bad as much as they clog up, you should also check your pick up tube they often have a screen hidden in them that also clogs. Discard the screen. I shouldn't tell you to remove the syphon valve but if you do its a good idea to replace with a shut off valve. Also you should have a water separating filter before you pump.
Jim

offthefront

Mcmaster-Carr has them .. "Cracking Pressure" from 1lb to .3lbs ... "check Valves" but I assume they are the same thing .. mine are 3/8" at the tank but then neck down to about 1/4" at the barbed end ...I'm going to check what the bigger HP formula's use ....m

http://www.mcmaster.com/ctlg/DisplCt...MMainWidth=812