For Rodbolt 2002 F200 yamaha low idle stalling

[Fishhead1974]

I have same problem with having to prime the bulb at low speed after running.I have saw all the posts you have on the check valves,I checked all hoses with a vacume pump mine all check ok no leaks.air box check valve ok and the 10psi check valve checks ok.the question I have for you I put a clear line between the check valve (10psi) and the tee,when the LP pump is running the fuel is cavatating the pump stops the line is full of fuel.is this normal?

[rodbolt17]

if the LP check valve is NOT leaking. check the filter head for corrosion where the filter gasket meets the metal.
this will be on the hull mounted water separator.

[Fishhead1974]

F200

Rodbolt did vacuum check on water separator no leaks.Ran clear tubing between 1st filter and tee before LP pump no bubbles, Also reposition the primer bulb arrow up.Vacuum checked the line from LP pump through the tee and F filter to vst no leaks.I do not understand why there are air bubbles after LP check valve. I did notice I had to reprime it more when it was hotter in the summer. Thank you

[rodbolt17]

did you actually remove the lift pump check valve and test it to break at 10 PSI and seal on the vacuum side. it MUST break about 10 PSI AND it must NOT leak when closed.
means when you pressurize the valve it must build to 10 PSI then release but once it pops open it must seal and hold 10 PSI.
if it doesn't its leaking.