outboard with twin fuel tanks

[billyboy]

I have a 19' outboard with twin fuel tanks, one on each side of the boat. If I run one empty, then start the other (25 gals each) the boat will lean. The fuel filter is set up so that either tank or both can be selected at the same time. Any disadvantage to running with both feeds open, do you think the engine (150 merc 1999 efi) can suck from two tanks at the same time. Do you think they'll empty evenly. I guess I could just try it, but thought I'd ask first. Thanks Bill

[Instigator]

I don't see a problem.
I've run several O/B's with dual tanks but never on the sides and I can see your problem.
Your motor should pull both at the same time, not sure how even it will drain but I'd think it should be fine.
On my last one, I ran the diverter valve up to the dash so I could switch back and forth from the drivers seat.
If it does'nt work off of both at the same time, that might be a good second option.
Lots of guys on this board with dual side tanks, lets see what they say.
Gary

[WILDMAN]

I run 2 tanks, one to each moter, so that won't help you. 50 gallons will last a good 1 1/4 hours!

[BoatGoFaster]

I have 2 tanks, one on each side. If they are both open, they will never empty evenly. Neptune see's to that.

I used to have a brass valve in the back and switch from tank to tank. Since then I have moved up to the big time. IMCO has an electric valve that switchs tanks from a switch on the dash. Works great.

You just have a straight EFI. But if you have an outboard that returns fuel to the boat, they also have a switch with 2 banks, so that it will also return fuel to the same tank that you are drawing from.

[Raceman]

Seems to me that if both tanks were T'd to one feed line with no restriction between the two, the level would stay the same in both (fluids seek their own level) I had an old Sanger V drive years ago that had tanks in both sides and an equalizer line, but seems like the T would do the same thing.

[billyboy]

Thanks for all those replies. Tman, maybe in your old Sanger the tee was low in the bilge. My valve (tee) is higher than the tops of both the tanks. Looks like I may just have to go out and try it. My concern is running the engine lean, if I'm pulling air on one side and gas on the the other side of the tee. But if that were the case, I doubt the engine could pull even a lean mix from the tank that still had gas in it. How much gas do you use in 1-1/4 hours? WOW!!

[Sleekster]

The only time it's really noticable is if I use the port tank first.

Boatgofaster, the electric valve looks like a great upgrade.

[Riverratt]

I have a switch in my dash that I can contol the 2 22gallon tanks. I have one in each sponson. Doesnt seem to affect the performance if I empty one side first. It is still fairly balanced and no noticable handling problems.

[Blade]

i think some tractor trailer rigs that have 2 tanks have a line to tie the 2 together so fuel level stays equel in both ,buta seperate line feeds from 1 tank to the motor.and only 1 fuel level gauge.just a thought.

[patchesII]

i'm with raceman. with a tee and no interruption the tanks should drain evenly or damn close.BTW your right about the rigs there is a line that connects the two tanks to each other, the fuel finds its own level

[BenKeith]

My Stratos bass boat also has two tanks and don't see a problem on which tank to draw fuel from, any kind of valve will do that.

What do you do when you have a high volume fuel pump, regulator, and return line for the unused fuel. Like I'm getting ready to install. I'm trying to avoid having two valves, one for supply fuel and one for return fuel.

Thought about installing a transfer pump, but don't like that idea much either. Considered siphon tube between tanks so the tank I'm running will draw from the other but that won't get all the gas out of the other. Coast Guard, and I frown on installing a balance line in the bottom of the tanks

Has anyone faced this and come up with a better solution than having two valves.

[BoatGoFaster]

Well, for whatever ever reason my tanks never ran equal. The only thing i can figure is that te tanks do not stay even because in the water the boat is not level. There is wave action and the movement of the boat, turns etc. Now when you stop which side is more full - heavier. Now fuel runs to that side. Then when you run again its all moving again.

In theory, i guess it should work, but I never had that experience.

[BoatGoFaster]

Hey benKeith. Here is the solution for 2 tanks AND controlling the return line.

http://www.imcomarine.com/cgi-bin/vcat2/CatalogMgr.pl?cartID=b-2479&template=htx/temp2.htx&SearchField=category&SearchFor=SFV&hdrFile=hdr/SFV.txt&ftrFile=ftr/ACC.txt

[Techno]

The reason 2 tanks don't draw the same is the plumbing. If the plumbing isn't exactly equal your going to have more flow through the less restricted plumbing. Each 90 equals something like 10' of line.
Each fitting is a restriction and each rise in the line also.

[Rickracer]

But you knew I was gonna say that, right?:cool:

[BenKeith]

Hey BoatGoFaster.

Thanks for the input, very nice valve, looks like it would work great but I'm still suffering from the sticker shock. That valves more than I payed for the motor I'm going to use it on.

Rick, for me to use that, you will have to be able to save me a whole bunch of money.

Back to the fancy engineering on a solution that fits my budget.

I know if ya wanna play, ya gotta pay but not quit so much.

One more problem. Will be running Holley electirc pump. Normally electrics don't like pulling fuel. If I install the pump between the valve/valves and the motor, low in the bottom of the boat, will there be a problem. Should I plan to install two pumps, one at each tank?

Keith

[Ron V]

My Rapid Craft has the twin gunnel tanks but I can't run both at the same time. I don't have that much of a balance problem, though what I usually do is run the starboard tank most of the way out first, so that at least part of the time the port tank is offsetting the weight of me in the driver's seat. Then I run the left one out. But my boat is wide and isn't real tricky on balance and doesn't really fly high enough to have it matter much anyway. If you're concerned about it, just switch off on the fly every few gallons or so. I'm assuming you can switch while running; I do all the time.

[typhoon]

Don't forget to make sure both breather lines are exactly the same length, and in the same position side to side on the boat. You can have uneven air pressure on the different breathers which may slightly pressurise or create a small low pressure in one tank. You may even want to consider doing what some aircraft do, and have the breathers in the airflow, and set up so the tanks get a slight pressure feed.
I'd just have a line(biggish, say 3/4" or more, definitely biger than your line to the motor) from the bottom of both tanks to allow them both to be the same level, and draw off one tank. If you have fuel return, just dump it into the same tank you take the fuel from.

Regards, Andrew.

[JDillen]

I have a IMCO Valve that I am not using. If you are intrested, send me an e-mail at jdhxn@aol.com.

[Techno]

Get some throttle or shift cable. Hook up to use manual valves. Put the valves best for plumbing then hook cable up for operating valves.
The idea is NOT to use a jazillion cables but only one that operates a bellcrank to do the changing.

[Propster]

I have a simple electric soleniod to switch my tanks. Both fuel tank lines go connect to one side and one line to the engine comes out the other side. There is only one wire going to it. It is real small and super simple. I don't know who makes it, however, my interior is out, I'll see if there is a manufacturers name on it if you want.

[BoatGoFaster]

I do not know if anybody blew up, but they were discontinued due to liablity issues. I know the coast guard did not approve them.

The solienoid gets hot. Heat and gas is an interesting combination.

Mine was a black box with a big silver soliend on each side.

Maybe yours is different?.

[Sleekster]

J - shoot me an e w/ your price.

BGF, the Sleek is at the fiber-shop. Carpeting this boat will be easier than the V-King. On the valve, so yours is approved? Won't blow-up? After all the glass repair, I really don't want to burn it up. I know the Vikings did that to their dead leaders, but this captain is still kickin'! I hope to be ready for the holiday weekend.