fuel system issues

I have a problem keeping and engine running from my starboard gas tank. This problem came about after there was a list in the boat, so i decided to run both tank of the starboard gas tank, they ran fine, but with further investigation i wasn't pulling from the starboard tank and assumed my gauges were lying to me.

starboard engine to starboard tank and port engine to starboard tank= port engine shuts down

starboard engine to starboard tank and port engine to port tank = starboard dies

starboard engine to port tank and port engine to port tank = both engines run well

i haven't tried putting port engine to starboard tank and starboard engine to port tank yet, but i can fail the engine with the test.

I went from thinking i had a cooling issue to a fuel issue. problems started after i changed a thermostat, so i assumed it was a cooling issue. poked around in the engine tracing all the way through the cooling system and finding no problems to concluding it was a fuel supply issue. i traced through the fuel system with everything good but the problem with the engines running from the starboard tank. proper ventalation to the tank so they are breathing fine. i am not too sure how the system draws from the tank when i move the selector valves around. what is the common factor between the engines since i can get the both to fail when i want as long as they are taking gas from my starboard tank.

I'm not sure how this fuel system works with twin engines and i am unable to find a diagram to explain what i may have to replace.

Re: fuel system issues

You may not find a diagram for your boat.

There's frequently an anti-siphon valve on fuel tanks to prevent fuel from siphoning out if there's a leak in the fuel system downstream of (and lower than) the tank.

If that anti-siphon valve (which is just a weak spring-loaded check valve) gets debris in it or gets a little corroded, the ball can stick and the fuel pump will not have enough suction to pull fuel through it.

Same thing can happen if your fuel pick-up screen becomes clogged with debris.

There's not much to an anti-siphon valve and they're usually fairly easy to replace.



If you have the tank out you can easily flush out the tank and inspect both.


Regards,


Rick

Re: fuel system issues

I will check the anti-syphon valve out along with checking the screen. thank you