Gas tank valve question

[rebars1]

I hope this is not too silly of a question...My boat has two gas tanks with fuel lines meeting at a "T" valve. Then a single line goes from the valve to the fuel pump. My question is how can one tell which tank is being used? The handle on the valve is pointing to the single line to the fuel pump. Do they both draw equally? Does the valve allow for using one tank at a time? Is it better to use one side for a while, then the other?

 

[ziggy]

Re: Gas tank valve question

i just bought me a t valve for my two tanks. yep, it allows for one tank at a time. there are three outlets. when ya turn the handle there is for all pratical ways of saying it. a L in the ball. so my valve can spin into 4 different posistions. 2 posistions do nothing as the feed to the fuel pump is blocked. the other two posistions are either port or starboard tanks. i don't see a good way of finding out yer question with out takeing the valve out and looking at it. or, find a posistion that it runs on. use that one. see what tank goes empty. when ya know one posision, then ya can deduece the other. right..... maybe??? hope someone else can help ya out better than that.

 

[Dunaruna]

Re: Gas tank valve question

The level in the tanks equalise, they draw equally. The valve would be there only to shut off flow to the pump. <br /><br />Aldo

 

[Don S]

Re: Gas tank valve question

If you look at the handle of the valve, the long part is the tail of an arrow, and on the other side of the screw that holds the handle is kind of a point or pointer. It points at the opening that is open.

 

[ziggy]

Re: Gas tank valve question

ya beat me with yer thread dunaruna. how do the tanks equalize. with a valve as i discribed above, one tank is on. the other three posistions are blocked. ??????(even though its a three outlet valve. there are 4 detents, the valve spins 360*....???<br />also, i've got feed line blues anyways, i have a t fitting right now. that kinda works like you discribed when i have both fuel tanks turned on at the shut off's. equalizing. i'm not happy with that arrangement at all. the t that is. <br /> i didnt read it well. no valve. just a t. yep, they did equallize in that arrangment... i stand corrected. always wondered what happens when one tank is empty. wont it at that point start sucking air and leave ya down???? i never let my tanks get that low to find out that answer, and am workin on the t-valve for my duel tanks.....

 

[ziggy]

Re: Gas tank valve question

after re reading (will be working on reading here soon)a few times. it does say a t-valve. back to my original question. how does that equalize?

 

[Dunaruna]

Re: Gas tank valve question

Rebars has got the 'T' of the valve pointing towards the pump, that leaves both tank lines open. He could (as Don eluded to) point the handle towards one tank or the other and it will draw from that particular tank. The shut off part of the valve is 180 degrees from the handle.<br /><br />Unless you have two seperate fuel gauges, it's probably best to leave the handle where it is.<br /><br />Some dual tank setups have two seperate fillers in which case they won't have an equalising hose, if it's got only one filler there will be an equalising hose down low, probably out of sight.<br /><br />Aldo

 

[rebars1]

Re: Gas tank valve question

Thanks for the input. I have two guages but only one works. One tank is original (steel , 1971) the other is plastic. The guy before me said he replaced previous tank because it had started leaking. The valve is in a difficult location to reach, up under the top of the transom. I have not turned it because I was not sure if I should. It's location leads me to believe it would be tough to switch tanks while out on the water. Also, I don't think there is enough clearance for the handle to rotate all the way up 180 degrees. I assume I could have left, right, or both, but not off.<br /><br />Since the tanks are ventilated, does the gas get sucked/siphoned out instead of pressure pumed?

 

[ziggy]

Re: Gas tank valve question

thanks, that does answer my question. 'rebars has got the T of the t-vale pointing twards the pump, that leaves both tank lines open." yep i can see it all, if his valve has a t in it. the one i just bought from iboats has a L in it, not a T. i guess we haven't discussed whether he has one fill or two. with one fill, i can dig the equalizer hose. and the equallizing. i had not thought of that set up. as i have two fillers. thanks..

 

[Dunaruna]

Re: Gas tank valve question

Rebars, the plot thickens!<br /><br />Have you got two fillers? (I suspect - yes)<br /><br />What motors are you running?<br /><br />Where are the tanks? (Both under the bow, one under the bow and one under floor.........)<br /><br />Aldo

 

[Don S]

Re: Gas tank valve question

Those tanks are not going to siphon back and forth, what do you think they put anti siphon valves in the system to prevent. <br />The only reason a Tee works between the tanks is the tank with the least amount of fuel in it has the most resistance and the fuel pump will pull from the fullest tank first. If that tank drops below the other tank it pulls again from the fullest.<br />No siphoning back and forth.<br />If you have one tank full and one empty, and the boat just sits there, that tank will remain full, and not transfer over.

 

[ziggy]

Re: Gas tank valve question

rebars, themz fuel gauages are a bummer to get to work. can't tell ya how many times dad(he had the boat before me) had themz stupid gauges worked on. i got two gauges too. both are working at this point. check for a loose ground wire, thats what mine was. loose like, not connected. as for the placement of yer valve. that's why dad had the remote baitwell valve installed. don't think he got what he wanted, and i can't belive a merc dealer did that for him either, but that's beside the point. it did work good, but bet the uscg would not be happy about his setup. <br />so do ya have one fill or two? <br />i thought that the fuel pump sucked fuel into it(out of the fuel tanks), and pumped it out(to the carb in my case)...a diaphram type pump, self primeing.....real mechs??

 

[Dunaruna]

Re: Gas tank valve question

I bow to your experience Don. You see a lot more of these setups than me.<br /><br />All I can say is that my boat was built mid seventies and it has two tanks, one filler, one guage, an equalising hose AND an anti-syphon valve in the feed line. The tanks equalise via a 2" connecting hose down low.<br /><br />I don't see what an anti-syphon valve has to do with equalisation.<br /><br />Aldo

 

[rebars1]

Re: Gas tank valve question

Hey ziggystardust, I have a 1971 Trisonic 18' trihull, Merc 888, Ford 302 188hp. Both tanks are next to the transom, one on each side. I have two fillers. I've been restoring the boat and have not been able to run it long enough to see if both tanks get used. I should be able to get it out this weekend (finally)<br /><br />I got the guage on the new plastic tank to work. But it looks like the sender on the old tank needs replacing (thanks to testing proceedures given to me in the forum!) as it always reads 1/4 full, even when it is completly full.

 

[ziggy]

Re: Gas tank valve question

cool man, i was starting to think i had the only trisoinc around, i know of no one else. seems like a good enough boat to me. i had the port tank out of mine when i was a kid. sure wasnt fun to get out, and i got a straight 6, so had some room. same as you, needed a sender. bummer to hear ya had one rust out. hope i don't get that, lol. <br />yeah that yer getting out this weekend. i got a few things to do to my trisonic before i get it out though. did get out on the pwc yesterday though, ..<br />anyways i got a question for you. seems like yer set up is most likely just like mine. where exactly is your 3 way valve located? whats it mounted to, a block of wood, special bracket? someone got to my fuel system and clustered it up. seems like i remember when i was a kid that the fuel tanks had copper lines, going to the fuel valve, but i cant rembember where the valve was located, but rembember it being hard to reach and discreetly located as you say. seems like it was on the port side, but that don't seem logical to me since my fuel pump is on the starboard side of i IL6. can ya help me out???

 

[Don S]

Re: Gas tank valve question

The tanks equalise via a 2" connecting hose down low.<br />

ALDO<br /><br />Man, I don't know about Australia, but here in the US, you have NEVER (Well, for as long as I can remember) been allowed to have connections on a "GAS" tank except at the top of the tank, never at the bottom......especially 2". Diesel tanks yes, but not on gas. Are you sure your boat has a factory setup and not an owner modification????

 

[Dunaruna]

Re: Gas tank valve question

It looks 'factory' and I gotta say, it's a sweet looking job. <br /><br />Your diesel comment has me thinking, my boat had a diesel option back in the seventies <br /><br />Aldo