Fuel Tanks not drawing down equally

[johna]

I purchased a DE boat recently and have been learning how to run it. Having a great experience with it so far until the last few trips when I noticed the fuel consumption between the P&S tanks is not even and getting worse. Can someone help me out with what the issue is ? Dirty fuel filter ?

 

[hntrss]

I think this is never an exact science. First check your valves on both feed and return. Make sure none have been accidentally closed at all. If all 4 are wide open, start to experiment. If there is one tank staying way more full than the other, try incrementally closing the return valve ( very small adjutments) to that tank. This should return more fuel to the lower tank. Trial and error. When it is critical, as in long trips, run one tank at a time.
If you have filters on each tank, it could be a restriction as well

If it is gas powered, you only have feed lines to play with. Choke off the tank that is burning more fuel till you even them out.

 

[Duke]

I fought that battle for a couple of years and finally gave up. I run on one tank for a couple of hours and switch to the other. I have an equalizing line between the tanks and that just made the equation more complicated. Also, I like to leave the equalizer closed in case one tank gets contaminated, it won't flow to the other tank.

 

[OLD BAY]

I fought that battle for a couple of years and finally gave up. I run on one tank for a couple of hours and switch to the other.

X2 on that!

 

[Bawugna]

I have a gasser and 2 tanks. Early on when I bought the boat I tried leaving both feeds on and never got the tanks to draw equally. Each is filtered and then there is a central filter that takes it to the motor. I just run one tank at a time and keep them equalized by switching them. I run one down a bit then switch and so on until it is time to fuel back up. It is not such a hardship. Embarrasing story, before I realized that they were not feeding equally, I ran one tank dry and the boat would run with a terrible list, because it kept running I just figured that it was drawing equally and all was good.......then I realized the tank was dry.

Just switch em'

 

[MDI45]

Johna,Don't drive yourself crazy....run one tank and return to the same tank at a time .....if your doin long trips out on one back on the other....this gives you two choices in case you have a problem with one side

 

[MASTERENEGADE]

I do exactly what mdi45 does. No issues and easier to keep track of fuel consumption with a good log book

 

[captjohn]

Are you letting both tanks feed the engine at the same time? Or are you running on one then switching to the other? I'm going to assume we're talking about a single engine boat here. If your feeding from both I would NEVER expect to see the same amount of fuel being used. Small differences between the length of the lines creates restriction, differences in the restriction in the valves, restriction in filters. The engine is going to naturally draw more fuel from the side with less restriction, so you would expect to see some difference. Also, running off both sides at the same time is a great way to contaminate both tanks if only one happens to be contaminated, via the return lines. Bottom line, I would never run a single engine off both tanks at the same time.

 

[offshore31]

agree with mdi45. out on one, back on the other.

 

[johna]

Fuel tanks not drawing equally

Thanks for all the great advice. I am running a single diesel engine from 2 tanks and could switch between tanks out/in, but the valves are tough to get at. I mean you have lay on your stomach and reach way back for them. If that is the way to go I will have to find a better place to locate the valves. Thanks.

 

[starrfish]

gave up the 'balancing act' a long time ago.. never worked out for me.. customers normally sit on the port side causing the return to favor that side..fuel line lengths, bends etc..log book math ...installed a flowscan, ran on one tank till she sputtered 150 burnable gallons per side. done. also installed those 3way ball valves, one for the feed and one for the return. takes about 5 seconds to switch tanks now. take some time this winter and make it easy for yourself.
a question for the 'contaminated tank' thoughts, what would contaminate 1 tank alone and not the other? unless your getting fuel from 2 different sources/ marinas?

 

[captainlarry84]

Johna,Don't drive yourself crazy....run one tank and return to the same tank at a time .....if your doin long trips out on one back on the other....this gives you two choices in case you have a problem with one side

Correct this is the best advice. Always run & return to the same tank. Make sure you have the correct type fuel valve that allow you to do that. The best valve made are the Watts Regulars # 8438. The picture shows two seperate tanks feeding one motor. The valve are in an easy place to switch back & forth. Every 50 gallons I switch tanks to keep the boat trim.

 

[cb34]

Return flow

Anyone know approx. how much of each gal of fuel that runs thru an electronic motor is returned to the tank?

 

[MDI45]

Anyone know approx. how much of each gal of fuel that runs thru an electronic motor is returned to the tank?

I have heard 3/4 gets returned....I don't know for sure but its a lot at idel

 

[delucat2]

Most fuel systems pull 60 GPH or more, one GPM at least.

If you are making 150 hp, you're burning 8 gallons per hour of the 60. 8/60 15% or so of fuel drawn from the tank is being consumed.

 

[Duke]

Contaminated Tank

I had a deck fill on one tank that had a cracked o ring that starting leaking water. It eventually leaked enough to be picked up and fill up my water separator. I switched tanks and came home from fishing. I ran on the single tank for the next two weeks until I got the water out of the tank and figured out where it was coming from.

 

[johna]

Thank you for the good advice. I will repipe the fuel lines to a better spot for access and use the 3way Valves. Good winter project. Any suggestions on the best fuel line to use?