Mercruiser loosing fuel in filter in rough water

[lkn_boater]

I have a 2013 5.0L MPI engine that will not start after sitting in water that makes the boat rock. I have found taking off the fuel filter shows that the level of fuel has gone down about 1 inch. If I fill the fuel filter up and reattach, the engine will typically run fine. I later found that if I give it full throttle, it will clear up the problem (when the fuel is low in the fuel filter, the engine starts, but will only idle, and eventually dies). The last time out, things got worse. I had to fill the filter 3 times and full throttle before the engine started running correctly. I have installed a check valve in the supply line from the gas tank, thinking the gas was going back into the tank, but that did not help. This problem has been happening on and off for about 5 years. A month ago when I took the fuel filter off the part that the fuel filter screws onto came off with the fuel filter. I tried reattaching with thread sealant but that didn't make a difference either. Not sure what to try next. Thanks for any insight you may have!

 

[alldodge]

Either a weak pump, antisiphon valve is clogged or there is a air leak in the fuel system leading to the pump. With the filter being sucked down I would look between filter and tank, including the antisiphon valve and if its tight

Have a motor serial number?

 

[lkn_boater]

The serial number is 2A048404. So I have never smelled gasoline during this problem, if there was an air leak wouldn't I smell it (scary!) I just don't understand where the gas is disappearing to. It should not be going back into the tank since I have the check valve to stop it. Is it normal for the gas to disappear somewhere after the filter? And then I can see a weak fuel pump not being able to fix it. I can check the antisiphon valve as it may be stopping the filter from refilling. I've seen that the fuel pump is port side behind the front engine mount. It doesn't look easy to access. Is there repair instructions I can look at to see if this is something I'm capable of working on? Thanks!

 

[alldodge]

The filter should never empty out some unless there is an air leak, the tank pick up tube broke off or the tank is out of fuel

Take a gas can and a longer length of gas line and connect to the fuel filter and place the other end into the can. Then take for a run and see if same issue comes up

 

[lkn_boater]

I decided to look between the filter and tank like you suggested. When I took the anti-siphon valve off and tried to push in the ball, it stuck and then was free to move. Maybe that's been the problem. I also changed out my pickup tube just in case, although I couldn't see anything wrong with it. Hopefully that was my problem. Thanks alldodge!

 

[alldodge]

Use carb cleaner on the valve