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.

 

[Pete]

Curious, what is your work around that allows you to move on without dumping fuel?

Pete

 

[cb48lrc]

All valves are in my normal run position. Still can't figure way I dumped fuel, but all is well for now. Should be in Key West on time, 10/20.

 

[captddis]

FWIW, One of my fuel valve was leaking internaly and filling up the the keel tank even though the valve was set to the aft tank.

 

[JLR]

Did you ever find out what caused this?

 

[divert00]

I was called to a marina acquaintance’s new to him mid90’s 50 Convertible. He had bought and moved boat with both engines drawing and returning to forward tank (as he found them at time of purchase). He recently filled aft tank, but returned to slip with no changes to valve settings.

Owner comes at a later date and switches valves for both engines to draw and return aft tank. Starts starboard engine and in a few minutes, fuel gushing out aft tank vent. Shuts starboard down, starts port, no problem. Calls me (I have 13 years Hatt ownership), I walk over and verify above. Move starboard to return to forward tank and no problem. Change back to aft tank return and vent gushes. Change starboard supply to forward and back to aft tank; no change in symptoms. It was too hot to spend any more time in ER, so we left. Man, those Detroit 12V’s return a lot of fuel!

My theory is starboard engine is drawing from forward tank, no matter the position of its supply valve. Seems same as original poster. Thoughts?

John McCarley - USCG 100T Master
Water Colors
Wrightsville Beach NC

 

[Captain Ralph]

There may be 3+ different types of valves used thru the years. Can you post some close up pics of the valve body, stem and handle.
My first swag, a handle is not in the correct position on the shaft.

And yes, the larger 12V71 pump can really move some fuel.

 

[rsmith]

Return valve is bad leaking fuel to the other ports on the valve. There are oRings and seals in these valves that go bad I had to replace mine some years ago due to air leaking in under suction causing bubbles in the fuel system. Rubber parts don’t last forever

 

[tomfishn]

Hi, Now we are having a problem with the oil change pump.
This is the same valve that Hatteras used for the fuel lines so
I have rebuilt the Groco SPO 80 R 24volt pump rebuild kit that I received from Sams Marine.
I still can not pump the oil back into the engines. I have one more test to do and that is to
take the valve out of the picture. and see if the pump will pump the oil into the engines. I
talked to Sams Marine and they no longer have the valves at $400.00 each. I am told these
possibly have to be replaced does anyone have a idea of a replacement with out an major
modification. I have found a Groco 5 port valve that looks to work and then found a Conbroco
78-124-01 5 port valve 1/2 inch that looks closer that may work. I am not sure the bolt pattern
will fit. Please advise if you have had this problem and which valve you used. I have also been
told to replace the pump and valve system. Please provide any thought. Tom Crittenden 1993
50 ft Hatteras True Love 111