Fuel Selectors

[Bulldog]

I just bought a 1990 Sabre Fast Trawler with 8.2 Liter Detroits. The fuel seems to be migrating from my port tank to my starboard tank (vice versa). Usually resulting in an overly full tank on one side and a near empty on the other.

I checked the schematic in the original owners manual and found that there are 3 on/off valves. One for the port tank, one for the starboard tank and one in the middle. Currently all of the valves are open. I am thinking that the middle valve in the "off" position would dedicate the port fuel to the port engine and starboard fuel to the starboard engine.

Does anybody have any thoughts on this?

Thanks!

 

[psneeld]

what sbout the fuel return lines and valve(s)?

 

[OldDan1943]

Look for the return valves. Sounds like you have it returning to opposite tank that is providing fuel.

 

[Bulldog]

Not sure. How are the returns supposed to be set?

 

[OldDan1943]

Not sure. How are the returns supposed to be set?

The return should be set the the supply tank unless transferring fuel.
Hunt around and look for the return valve manifold. It should be at or near the top of the fuel tanks

 

[Bulldog]

The return should be set the the supply tank unless transferring fuel.
Hunt around and look for the return valve manifold. It should be at or near the top of the fuel tanks

Should the return valves be open?

 

[OldDan1943]

You will find values one to return to the port tank and the other to starboard. If you are drawing fuel from the port tank, the return to the starboard fuel tank should be closed and the valve to the port tank open. If your fuel tanks are cross connected, then, folks will cross connect their returns.

I understand your excitement and desire to get underway but take some time, trace the fuel lines and other systems.
Get a knowledge person or employ a captain to spend time with you, going through the "systems" so you feel more comfortable.

 

[markpierce]

The return should be set the the supply tank unless transferring fuel.
Hunt around and look for the return valve manifold. It should be at or near the top of the fuel tanks

I totally agree. If piping doesn't allow that, correct the situation.

 

[dhays]

I understand your excitement and desire to get underway but take some time, trace the fuel lines and other systems.
Get a knowledge person or employ a captain to spend time with you, going through the "systems" so you feel more comfortable.

I second this. This can be really important for a couple reasons. First, spilling fuel out of an overfull tank is not only an environmental no-no, it can get really expensive in a hurry. Fines are serious.

Also, if you inadvertently close off the fuel return lines and the engine is running, you can do some serious damage to fuel system or engines if you have a high pressure fuel system.

 

[The Other Gary]

My fuel selector panel is easy to manage. There is no crossover between tanks, fuel transfer is managed by selecting the draw and return for each engine and the generator. Bad fuel in one tank cannot be transferred to the other except by going through a filter.

 

[Conrad]

My understanding of Detroit diesels is that they have a high return flow rate vs other diesels so that should be considered as well.

Mind you. that may only apply to their two strokes; not sure.

 

[Sailor of Fortune]

My understanding of Detroit diesels is that they have a high return flow rate vs other diesels so that should be considered as well.

Mind you. that may only apply to their two strokes; not sure.

2 stroke Detroits have a high rate of return. The OP has 8.2's, which are 4 stroke Detroits. I don't think they circulate fuel as the 2 strokes do.

 

[Captain Ron D]

I just bought a 1990 Sabre Fast Trawler with 8.2 Liter Detroits. The fuel seems to be migrating from my port tank to my starboard tank (vice versa). Usually resulting in an overly full tank on one side and a near empty on the other.

I checked the schematic in the original owners manual and found that there are 3 on/off valves. One for the port tank, one for the starboard tank and one in the middle. Currently all of the valves are open. I am thinking that the middle valve in the "off" position would dedicate the port fuel to the port engine and starboard fuel to the starboard engine.

Does anybody have any thoughts on this?

Thanks!

In my prior boat, a 38' sportfisher, it had the lovely 8.2 Detroits. I had a single tank but here is what your problem is. Those engines have fuel pumps that over supply the injector gallery, and the excess is routed back to the fuel tank. Depending upon how the plumbing is, the excess could be routed from both engines to only one of the two tanks. You need to have the 'cross over' valve that plumbs the two tanks together, OPEN. That will keep the fuel balanced between tanks. This will should up if you have the cross over valve closed, and one engine uses more fuel than the other, which is common with those motors. Then the tank supplying the engine that draws less, will result in being higher level than the one supplying the engine that uses slightly more fuel. When that happens to excess you will begin to list to one side or the other. That is why the cross over valve is there. My current trawler has dual tanks and a crossover to supply only a single diesel, and when I got the boat that valve was also closed and the supply came from one tank and the return went to the other ?? Go figure that one out !!! Hope this helps. Captain Ron D.