Fuel valves

[cb48lrc]

See if you can get your head around this one.
48LRC, 4 fuel tanks, stb,port,forward,and aft. I normally run stb supply from stb tank and stb return to stb tank, port supply from port tank port return to port tank. All tanks were full. A friend stopped me and said that I had fuel coming out a vent. He was correct, fuel was comming out the aft tank vent. All fuel valves were in the normal run position ( confirmed 2 times). By switching the all valves to the aft it stopped. Had a mechanic remove all valves and confirmed that they were working correctly and the handles were correct. Changed back to the normal run position, 6 miles later here it goes fuel comming out of the aft vent. Mechanic came back spent 4 hrs and we still cannot see how I am over filling the aft tank.
I am open to suggestions but not criticism.

[Avenger]

Where is the generator drawing/returning?

[cb48lrc]

Should have said that, 15kw from and to forward tank. 9kW from and to aft tank. That said when the problem happened I was not running ether generator.

[JLR]

I had a somewhat similar situation. Although I was never quite sure what the fix was, it appears that the position of the handles being turned to exactly the right spots cured the problem. In my situation, it turned out that both engines were pulling and returning to the same tank. Each engine should have been pulling and returning to different tanks just like your handles were set to do. You are obviously pulling from one tank and returning to the aft tank. I even went so far as to buy the new valves from SAMS but seemed to fix the problem before needing to install them. I know that job is a time consuming and crappy one. Although it should not matter with these valves, it appears as if they line up better with the actual holes when turned in one direction to get there rather than the other. I am anxious to hear what you find to be the problem.

[Finalee]

At least one of the side tanks is returning to the aft tank. I really can't see another answer.

[cb48lrc]

The port tank is down more than the stb, telling me that the port engine was returning to the aft. But after disconnecting the aft return lines from the valves we had no flow out of the valve ports.

[MikeP]

Was it working properly for days/weeks/months and then just began doing that "on it's own" with no changes to valve position or fuel line replacement, or other maintenance to the fuel supply system, etc?

[cb48lrc]

Before going into the boatyard, I was running the port from and to the aft tank and the stb from and to the forward tank. After filling up all tank I went back to my normal. Port from and to port, stb from and to stb.

[JLR]

Did you find the problem?

[cb48lrc]

I have been running with port on port and stb on stb. Have not switched the valves. We disconnected the return valves, everything was as it should be. The mechanic and I were and are confused. I will post again when the valves are changed.
It has been a trying time since we left N.C. this year. Problems with the new Balmar regulator, and smart gage, not to mention a AC blower motor going bad. All seems good today, time to keep heading to Key West.
When I can I need to give a full report on the Balmar problems, interesting but aggregating.