I have (2) gas tanks that I want to connect as one.. My ?'s are If I put a T to connect both tanks (5/16) will they both work as one.. and me a correct gas guage reading.... Second ? is when I have to fill them up will I have to fill both separately because of the 5/16 gas line.. Thank-you for the help.....
Connect the line between the tanks low or on the bottom of each tank, be sure that the line does not go above the bottom of either tank and they will act like one tank. Any place that the line goes above the bottom of one of the tanks will set the level of the fuel that you can get out of that tank. With the 5/16 line when you fill it up the tank that is filling through the 5/16 line will fill very slowly. Make the line bigger. Rex
I've never plumbed dual gastanks on a car, but I have two heating oil tanks in my house with one gauge that works accurately. The key is to have a "T" connector at the lowest level for crossover and another at the highest level for venting. The liquid will settle to it's own level, the same in each tank. When filling you have to fill it slowly enough for the crossover to bleed over to the second tank. 5/16 sounds kind of tight to me.
I had a 1967 Sunbeam Alpine with 2 small tanks, one on each side of the trunk with a 2 inch or so pipe/rubber hoses connecting them. only one filler, this was factory. as stated your planned line to connect the 2 seems way too small.
since ther are only 5/16 barb hose fittings on both tanks (on th ebottom) I can only use that..... But as long as it will self center and give me a correct gas readding( I had none at thi point) It sounds as if I can still fill both tanks from there orginal fill caps I do not mind doing that if thats all the trouble I will have.. Thanks again......
I have used one inch crossover with large 3/8 vents on both tanks. You still have to fill one tank, wait a minute, top up...wait a miunte and top a last time.....bigger crossover tube the better
Or just use dual senders and a diverter valve that switches the senders as well as fuel line. Doing one right now on my Toyota turbo diesel powered '57 Land Rover SW....I can post the pn for a quality valve if you want
Hooking 2 tanks like you originally suggested could cause the back tank to feed correctly, but over flow the front tank, if you have a return line on the fuel delivery system.
Mike 51 Merc has the right idea. "T" the vent lines from the 2 tanks. The 5/16 line will equalize the fuel level faster than you think. As long as the vent line T is below the fill pipes, the vent can help cross flow from the tank you are filling into. Just make sure the vent T is level with the top of the tanks, and the vent hose (open end) is above the fill pipes.
Connect the Two tanks together with a reasonable size hose between them at the lowest point. Then connect them together with a breather hose at the highest point so you will only need one filler. Now you can get really creative! [ optional ] In the lower hose between the tanks fit a one-way check valve so fuel stays in the auxillary tank [ the one without the filler ] Use two electric pumps plumbed into a "Y" for the fuel line and two fuel gauge sender units Use a 6 post "on-off-on" switch to divert the sender units to the fuel guage and also to switch on the appropriate fuel pump
You guys are making this WAY too complicated. Buy a simple diverter valve from Pollak. They have several models, and will switch your tanks and sending unit, even a return if you have it. Yes, both tanks need to be vented and the vent outlet needs to be high, as in the overflow tube on your fill tube like factory. You cannot use the vent to supplement fuel transfer as it will hydrolock. The vent has to be vented to atmosphere at a high point or it will pour fuel out on a hill or fast turns.....IF your filler is low, as in a bumper fill(I have a '70 Nova tank in my '54 chevy truck which fills below the tailgate )..then your vent needs to be routed to a high spot with a small filter on it as it will be sucking air in as your fuel is consumed. These have non-vented caps....your filler tubes that are way up on the qtr panel or cab have vented caps usually since your tank vent is tapped into the filler tube...Google or search Ebay for Pollak, you will ind a nice fuel/electric diagram...one simple toggle switch on the dash does everything and its a high quality part Hans
The pollak valve is a high quality motorized valve, not a solenoid valve that will burn out... Diagram: http://www.ebay.com/itm/POLLAK-FUEL...Parts_Accessories&vxp=mtr&hash=item2eb7e06106 3-port for non-return fuel systems: http://www.ebay.com/itm/Pollak-3-Po...arts&vxp=mtr&hash=item20c31f9156#ht_500wt_922 6 port for FI or Diesel: http://www.ebay.com/itm/POLLAK-6-PO...Parts_Accessories&vxp=mtr&hash=item2eb7e061e9 I got my 6 port for $65 . There are several brands that are similar, most are made by Pollak and re-badged... Hans
Add the valve. We have an Int'l dump truck with two side tanks plumbed together. If parked on a side hill gas runs to the tank without the pickup and you run out of gas.
It should work OK. You can fill the tanks separately no problem. The fuel will find its own level and the one gauge will give you an accurate reading on the level. The small line will prevent the fuel sloshing around on corners and hills. On a long grade the fuel will all run into the back tank or the front tank depending if you are going up or down but as long as you are aware of this it should not be a problem. If both tanks come with gauge senders you can wire them through a switch or push button which will allow you to see the level in each tank on one gauge but you don't have to get that fancy if you don't want to.
The 5/16 will do what you want it to do. The problem is as everyone has said, it's to small. It will take a long time at the pump when your filling up to get tanks to equal out. As for as the fuel pump delivery that won't be an issue.
I had a 2 tank setup (2) 7 gallon tanks. I had a 1 5/8" tube connecting the two together at the bottom, each tank had 5/8" dia breathers with a filler neck on one tank. Even with the 5/8" breathers it was slow going filling the tanks when they got past half full. If I had to do it over again I would have run two 1 5/8" tubes to each tank, one on the bottom, and another one about an 1" from the top. I had the fuel level sending unit in the tank that didn't have a filler neck. The one tank without the filler neck has to rely on gravity feed to fill it with fuel from the other fuel tank with the neck.
One thing to consider is how low will your connecting hose be? I ran over a dog in a older semi that I had a few years back that used a crossover between the two saddle tanks and it took out the crossover. It broke the brass fitting off flush with the tank, behind the shutoff valve. I lost about 50 gallons of fuel before I got a stick drove up in there to stop it up. Newer semi's now use a inverted "U" style crossover that works like a siphon. Very hard to knock it off by impact compared to the old lower style. Lots of semi's use one fuel gauge sender, usually on the low side [right side] and use dual pickup and returns. That way, fuel is supposedly always drawn from both tanks at the same time. They usually still have to be filled at the same time. I guess you could fuel one side at a time and wait for it to siphon over if you had a lot of time to kill...
Install a 1/4 turn shut off valve in that 5/16 line. Shut the valve fill one tank then the other and then open the valve. Much faster and a lot less money.
I'd use the valve and two fillers. I'm doing a setup like that now. rubber hoses are hazardous with ethanol. I use only steel or steel braid protected urethane lines. Plumb the valve so you can reach it while you drive.
I know that on trucks it is illegal to have a outlet on the bottom of a gas tank (probably the same with cars). There is an easier way to do this. Simplly take fuel out of both tanks using a tee in the fuel line, period. The gas will come out of the fullest tank first, then both tanks at the same time. Its so simple that even a monkey can do it.
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