100 four stroke - fuel issue?

[Tango]

I have the F100X on a Novurania RIB with 40 gallon built in tank. When the motor began stalling at low speeds I changed the fuel/water seperator, in line filter, and all the spark plugs. Following the above changes the motor barely runs at all.

I then bypassed the fuel water seperator - no change. I then bypassed the fuel filter and tried to run directly from a line attached to a gas can which was eleveated above the motor. Still no change. Somehow the motor will now run from the boats normal fuel system but it runs very rough. Note; the fuel filter never fills up - looks like it is running dry. I have checked the lines from the built in tank and they appear to be fine. There is a check valve at the tank connection - can this go bad? Fuel will enter the filter when squeezing the primer ball but then slowly disapears down the line. I removed a line from one the fuel pumps (one at a time) and they pumped fuel when running. I am at a loss. When running the boat on the dock it will run (very roughly) forever with what appears to be just a slight trickle in the filter. Should this filter stay completely full of fuel at all times? Even when not running?

Where do go next?

[Ken]

Tango,
That valve at the fuel connection at the main tank is an anti-siphon valve. It is notorious for causing fuel starvation problems - will stick and not allow fuel to flow when demanded by fuel pump.
Remove and clean or replace - it is just a spring loaded valve.
The local fuel filter bowl should stay full after you prme the bulb and when running. On my 2000 C115 the fuel will slowly drain back to the main tank after motor shut down, but this takes a half a day or so, and the bowl will be almost empty.
Good luck [img]smile.gif[/img] ,
Ken K

[Tango]

Ken,

That did it!. Took me a week to find the part but once in the boat the issue is solved. Thanks for your help and happy boating!