'87 232 Gulfstream with twins and dual fuel tanks

[tbell45219]

I have an older GW gulfstream with a main and aux fuel tank. When I acquired the boat I was told that the tanks were working "together" and I didn't have to switch to either tank. I've been out on it enough to refill a couple times and it seems as if one tank stays full (the forward gas port, I assume the smaller Aux tank) and I have to keep refilling the back gas port (I assume the main). My issue is that the aux gas is not being used and I don't want to run the main dry to see if it "switches over'. I have 2 fuel valves (see attached) near by oil reservoirs but no clear understanding. Any thoughts?

 

[wspitler]

Assuming you have two engines, one fuel valve for each engine, it appears you have each engine selected to both tanks. When one tank runs out the engines may suck air so I would not count on it automatically shifting over to the fuller tank. I run each engine off a separate tank unless I want to change the load balance on the boat. Also be aware that if one of the tanks has not been used in a long time that may have contaminated fuel in the bottom. It should not be too hard to trace the fuel lines that run back to the engines to determine how the valves work. Normally the pointer on the valve handle indicates tank selection.

 

[tbell45219]

Yes, I do have twin motors. I just questioned how these valves work. Do they have 3 positions Main, Aux and both or Main, Aux and Off? I just found it hard to believe that each motor can pull from both tanks at the same time or automagically.
I do know that it's been pulling from the main tank because 35 goals only gives me about 1/3 of a tank and my aux tank stays full.

 

[kirk a]

I’m viewing the pictures on a phone, but how many lines are on each manifold? I see only 3 each. If that is the case you likely have two lines coming from the tanks and then one line to a motor.

setting it in the middle could be both or could be neither. I’ve never set the valves on my express to the middle. Normally run one motor on main, the other on aux. if I get really low and run out on the aux I’ll then run both on the main.

as another poster mentioned it is a good idea to watch out for old fuel if that is possible.

 

[seasick]

Those look like Moeller gas selector valves. I assume that since your motors run with the handle in the middle position that support the both function. Apparently some do and some don't. I would have assumed also that if there is both selection, that could cause a dry suction condition but that would depend a few factors such as strength of anti-siphon valves, functionality of tank vents, condition of the gas lines, tank pickup screen etc.
Does your fuel gauge selector and display work? If so, I would try running one engine on main and the other engine on Aux and see if the motors work. If the valves are working, the gas levels in both tanks should change.

 

[Hookup1]

I use the valves quite a bit in the winter when I'm actively using the boat. I fill both of my tanks up (72 and 134 gallon) and run one motor off of each tank. Keep an eye on the fuel levels and make sure the fuel gauges work properly. As my trip progresses I turn the fuel over in the aux tank a few times - then I put 20 gallons in it (this is my reserve fuel) and switch over to both motors on the main tank. I try not to cut it too close before filling up but at least I have reserve.

By the way - don't let the engines run dry - switch tanks before that happens. If they suck the filter cans dry you will have a heck of a time getting prime back using the bulbs. Alway fill the cans up and put them back up - then pump the bulb.

 

[tbell45219]

Those look like Moeller gas selector valves. I assume that since your motors run with the handle in the middle position that support the both function. Apparently some do and some don't. I would have assumed also that if there is both selection, that could cause a dry suction condition but that would depend a few factors such as strength of anti-siphon valves, functionality of tank vents, condition of the gas lines, tank pickup screen etc.
Does your fuel gauge selector and display work? If so, I would try running one engine on main and the other engine on Aux and see if the motors work. If the valves are working, the gas levels in both tanks should change.

The gas gauge works that's how I know it's only pulling from the main. I've only put gas in it 2 times.
The Main is now at 1/8 a tank and the Aux is still full. I want to see if it will start using the Aux when the Main is empty but I dont want to chance it on the water. I may just take a 5gal tank in case it doesnt switch.
It will take to long to run the left over gas at the dock (and I dont want to waste the money).

 

[tbell45219]

@wspitler, there are 3 hoses to each valve. From what I understand, eavh valve has 1 hose for each tank and 1hose to the motor.
The center position that it is in is either for the main tank or for both tanks.
I'm really trying to understand how many positions the valves have and if it's possible for them to be set to use both tanks at the same time.

 

[Hookup1]

The gas gauge works that's how I know it's only pulling from the main. I've only put gas in it 2 times.
The Main is now at 1/8 a tank and the Aux is still full.

Have you tried putting fuel in the Aux tank? Are you sure it's full? You could be having a problem with that gauge.

I want to see if it will start using the Aux when the Main is empty but I don't want to chance it on the water.

The valve in the middle will pull "air" from the empty tank. It's has no way of knowing that it should pull from the other tank.

I may just take a 5gal tank in case it doesn't switch.

Do you have SeaTow or BoatUS? If you run them dry you will have a difficult time priming them on the water. 5-gallons in your how many gallon tank probably isn't enough to get the pickups to work. When you are running the fuel flows to the back of the tank where the pickup is. When you stop the fuel levels out and will not be reachable by the pickup when tanks are low.

Priming the filter and engine is a pain to do. If you haven't done this before you really don't want to figure this out on the water.

It will take to long to run the left over gas at the dock (and I don't want to waste the money).

My guess is your Aux fuel gauge isn't working. I would top off the Aux tank, put one engine on each tank with the valves and use the boat. Verify the fuel gauges are working.

As for running with the valves in the middle or both position - I don't recall anyone responding to your post that they do it that way. Maybe if both tanks were the same size which I doubt they are. But eventually you will be sucking air from the empty tank and loose both engines. Best advice is to learn to use your fuel valves and be aware of how much fuel you have in each tank.

I've run out of fuel on my boat twice. The first time was when the boat was new to me. Gauges were not working properly and I ran out of fuel on the reef in FL. SeaTow came out and delivered 10-gallons. Took forever to pump the bulb and get an engine to prime. Same with the other engine.

The second time I ran out was earlier this year. Fortunately it happed at the fuel dock. Had a interesting problem the other day getting fuel. Running off one tank to each engine. Both tanks low but had at least 1/8 tank. Ran to the marina that has a 1/4 mile long no-wake zone. Fueled the boat and went to start the engines back up. No start on either one - both crank fine. After short panic and then thinking about it I pumped the fuel bulbs for a while. Took engine out of neutral, tried starting, got them to sputter and then start running. My guess is moving at a slow speed with some extra weight up forward and low on fuel the remaining fuel ran forward and was not in contact with the pickups.

Running out of fuel

Had a interesting problem the other day getting fuel. Running off one tank to each engine. Both tanks low but had at least 1/8 tank. Ran to the marina that has a 1/4 mile long no-wake zone. Fueled the boat and went to start the engines back up. No start on either one - both crank fine. After...

www.greatgrady.com

 

[Legend]

There are many opinions on how to utiltize two tanks - since my tanks have 150 in one tan and 70 in the other I prefer to rub them both on one and then both on the second. To me it is too confusing to be monitoring 2 tanks at the same time .

 

[tbell45219]

I do have BoatUS but I will take your advice, I'm too knew to the boat to be figuring it out on the water..
Each time I put gas in I put some in both tanks and the last time, the Aux tank seemed to be topped off so I know it is full and the gauge reflects that. The valves have a bit of corrosion so I was a little hesitant to try and turn them. I will fill my main tank and run one motor off the Aux.

 

[Hookup1]

I do have BoatUS but I will take your advice, I'm too knew to the boat to be figuring it out on the water..
Each time I put gas in I put some in both tanks and the last time, the Aux tank seemed to be topped off so I know it is full and the gauge reflects that. The valves have a bit of corrosion so I was a little hesitant to try and turn them. I will fill my main tank and run one motor off the Aux.

The tank valves on mine look crapped up too. Give them a WD-40 spray and wipe them down. Use them a bit. They should be fine.

 

[glacierbaze]

Never had a boat with fuel valves, but from a practical point, and a safety point, it should have a shut-off position, not just 2 in, one out. Otherwise, it sees to me that once a tank is empty, the motor would continue to pull from the line with the least resistance, which would be air.
Hookup, when your selector is in the middle, does that shut off the supply line? Are there 2 middle positions, handle at 6, and at 12 o'clock?

edit: Looking at your red decal, middle position is off. If OP had the same valves, his motors would not run in that position.
Next thought is that the pick up tube in the aux tank could be the problem, clogged or disconnected.

 

[tbell45219]

So I still haven't figured out the issue yet. I've just been filling up the main tank.
I have been hesitant to change the fuel valves in order to feed from the aux tank (which is full of fuel).
My issue is that I don't know what position to change the valve so that it will pick up from the Aux tank. The valve will spin 360 degrees.
Does anyone have a similar setup?

 

[tbell45219]

Never had a boat with fuel valves, but from a practical point, and a safety point, it should have a shut-off position, not just 2 in, one out. Otherwise, it sees to me that once a tank is empty, the motor would continue to pull from the line with the least resistance, which would be air.
Hookup, when your selector is in the middle, does that shut off the supply line? Are there 2 middle positions, handle at 6, and at 12 o'clock?

edit: Looking at your red decal, middle position is off. If OP had the same valves, his motors would not run in that position.
Next thought is that the pick up tube in the aux tank could be the problem, clogged or disconnected.

It seams that my valves have 4 positions. From what I was told, the current (6:00) position feeds automagically from both tanks. I would assume that the 12:00 position would be the shutoff. I'm not sure which tank feeds the 9:00 and 3:00 positions. I can just as well keep filling the main 100 gal tank and forget about the Aux... but that's not me. I need to understand what's going on here. But not at the risk of safety (or having the boat down for a significant amount of time).

 

[seasick]

I found multiple reviews about this valve, It may be a 3 position or a 4. You can't easily tell. In addition several reviews mentioned that you can't rely on the pointed end of the handle to tell you which port is selected. Those folks had to figure out which tank was selected and then mark the valve body where the pointer was pointing.

 

[OceanSun]

Here is a diagram of your fuel system from the owners manual for your boat (available free at GradyWhite.com). If you're so worried about that valve being sketchy that you don't want to try to switch tanks then you should replace them ($32 Amazon x2) with new ones and start using both tanks purposefully. There is no automatic switching that will happen with that system and it's not pulling from both tanks at once unless a previous owner gutted the valve. Here's a video on Grady's website about best practice for using your tanks. 232 with twins is an awesome boat and I am in love with mine (2008 2x200's but single 150 gal tank).

 

[seasick]

Part of the OP issue is that the diagram shows the plumbing but not what the valve handle looks like when a specific tank is selected. As mentioned by several reviewers of the Moeller valve,, the pointed end of the handle does not necessarily tell you what tank is selected. One might assume that if a tank is selected, the valve would have to be turned 180 degrees to switch to the other tank. That is how I think it is but the reviewers disagree. Perhaps the confusion is caused by there being two versions of the valve, the 3 position and the 4 position. Th user manual shows the valve as a three way. Th Moeller web site offers no help or description of how the valves work