Fuel selector switch gone bad?

Hello all...here is the gremlin I am chasing:

The boat overall runs great. I have occasional to frequent issues of it bogging and acting like it is running out of gas, mostly on one of my two tank. I have done my best to trace down the problem:

Details
2003 50hp ELPTO
Two 6gal Mercury fuel tanks (fairly old)
One brass fuel selector switch (4 positions, 2 connected)
Two separate fuel lines from tanks to switch
One fuel filter just before the motor (that both tanks/lines share in common.)

I have a few more things to try, but I think the problem is either the switch or line from #1 tank (which I just replaced.)

Tank 1 and fuel line
- old tank, new line
- While it is really hard to ID with complete certainty, the problem seems to happen mainly on tank 1.
- Recently replace line from tank to selector switch, no improvement
- Last trip out, when the problem happened, I moved #2 fuel line to tank 1 and it ran fine all the way home.

Tank 2 and fuel line
- old tank, fairly new line
-More reliable than tank 1, but if I remember correctly, I still have an occasional issue with this tank.
- Next time out, I want to switch lines to see if problem moves.

More and more, I question the fuel selector switch. Anyone heard of a brass type "going bad?"

KRS

Re: Fuel selector switch gone bad?

Be sure the vent is not clogged up as it will not let fuel flow if there is not sufficient air flow

Re: Fuel selector switch gone bad?

It's very possible the valve has an air leak and will suck air and not fuel, or a clamp is loose on a hose and sucking air.
Easy to check, just plug the fuel line from the motor, directly into the tank and bypass all the extra valves, fittings, and hoses etc, and see how it runs.

Re: Fuel selector switch gone bad?

Since both tanks are fairly old, check the pickup tubes in the tank for pin holes or possibly that they have broken off. As long as the fuel level is high enough to cover the end of the tube or pin holes, the engine will run ok. Once the pin holes are uncovered or if fuel falls below the level of the pickup tube, yes, the engine acts like it is running out of fuel -- because it is.