HOW to remove old gas from internal gas tank

Dualie

Seaman
Joined
May 27, 2005
Messages
71
this may be a silly question, but what is the best way to remove the old fuel from an internal fuel tank.

my boat has a 66 alluminum gallon tank and i suspect the fuel is bad, probably with lots of water in it.

i am looking to remove about 25 gallons and using the old fuel (MBTE) in my mower. and then filling up with E-10 fuel.

question:
1) should i run a tube in from the gas cap on the side of the gunwale to the tank OR

2) run a manual bulb primer line vs. a mouthful of gas from the fuel/water sep. at the stern and that empty into a fuel can?

clearly, the boat needs to be pulled out of the water to get below the tank for siphoning..

i have heard that their is a valve in the gunwale side that may stop the hose from going all the way into the tank.

any suggestions??

thanks in advance!!
dualie
 

gewf631

Chief Petty Officer
Joined
Mar 4, 2003
Messages
489
Re: HOW to remove old gas from internal gas tank

Depending on where your tank is located, you should have an some access point to get to the fuel guage sender. I'd remove the sender, and use that spot to drop your siphon hose.

25 gallons is quite a lot, so this will give you a large enough spot to drop a decent sized hose, and should also be one of the lowest spots in your tank, so you should be able to get the bad stuff out.
 

xtraham

Lieutenant
Joined
Jul 20, 2006
Messages
1,425
Re: HOW to remove old gas from internal gas tank

you can buy a small 12 volt fuel pump for about 20 bucks or less from an auto parts store (thats what I use for draining auto tanks) hook it right to your present fuel pickup line, if you have water you might want to closer to the the bottom of the tank, like gew said remove the sender stick the hose in there and pump away.......
 

Bondo

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Apr 17, 2002
Messages
70,464
Re: HOW to remove old gas from internal gas tank

xtraham said:
you can buy a small 12 volt fuel pump for about 20 bucks or less from an auto parts store (thats what I use for draining auto tanks) hook it right to your present fuel pickup line, if you have water you might want to closer to the the bottom of the tank, like gew said remove the sender stick the hose in there and pump away.......

Ayuh,..........

I've gone as far as to Build a Transfer Pump this way,.........

It amounts to an Electric Fuel Pump mounted to a Stick,... With alligator Clips on Long Wires,+ some Hoses.......

I Just hook it to the Elbow on the Tank, run the wire to the Battery,+ Pump Away..........
 

Bob_VT

Moderator & Unofficial iBoats Historian
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May 19, 2001
Messages
26,019
Re: HOW to remove old gas from internal gas tank

I have in the past tapped into the fuel line and ran a hose out of the drain plug (in the transom) while the boat is on a trailer. I used a vise grips on the hose as a shut off valve and let the fuel drain into smaller containers. No priming just pure gravity.
 

tashasdaddy

Honorary Moderator Emeritus
Joined
Nov 11, 2005
Messages
51,019
Re: HOW to remove old gas from internal gas tank

i remove the sender, hose small enough to go thru transom drain, used oil change pump to get siphon going.
 

bamadave

Petty Officer 1st Class
Joined
Mar 24, 2005
Messages
391
Re: HOW to remove old gas from internal gas tank

One trick I use if you can remove the fuel guage sending unit is attach a stick of copper tubing to the pump. Place the tube in the low spot of the tank and you will pick up ALL the crud in the tank at the same time.
 

Bondo

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Apr 17, 2002
Messages
70,464
Re: HOW to remove old gas from internal gas tank

Did you guys that Siphon the fuel out the drain hole,....
Change out the Faulty Anti-Siphon Valve while you were Working on them,..??..??..????????????d:)
 

Dualie

Seaman
Joined
May 27, 2005
Messages
71
Re: HOW to remove old gas from internal gas tank

thanks for the great advice!!

i have a 20' center console and a fuel guage, tach, speedometer is on the helm, but i dont' recall an access cover on the deck.
I must have one right? Otherwise, how else would anyone get access to the sending unit.

Hopefully, its there- will check tomorrow and post results.

if its not on the deck, where would one think it would be located??

Dualie
 

studlymandingo

Commander
Joined
Mar 22, 2006
Messages
2,716
Re: HOW to remove old gas from internal gas tank

Mine is located under a panel underneath my console.
 

Dualie

Seaman
Joined
May 27, 2005
Messages
71
Re: HOW to remove old gas from internal gas tank

the boat is out of the water and time get going on this project.

bummer- of course, the sending unit is someplace that is not easily accessible. would hate to take off the helm.

so that being said, can i pull the fuel from the line that leaves the tank and hits the water/ fuel sep??

and if so, can i use a bulb primer hose to get it going and then use gravity to finish it off?

i am concerned about having any type of static or electrical componants near fuel being removed.

thanks
D
 

Bondo

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Apr 17, 2002
Messages
70,464
Re: HOW to remove old gas from internal gas tank

"and if so, can i use a bulb primer hose to get it going and then use gravity to finish it off?"

No,........

Boat Fuel Tanks have a Anti-Siphon Valve mounted in the Elbow at the Top of the Tank.............

It'll take Vaccum from a Fuel Pump to Pull the Fuel Out.........

Ayuh,......
You CAN mount an Electric Fuelpump to the Line at the Fuel Filter,+ Pump it Out from There.......
 

Dualie

Seaman
Joined
May 27, 2005
Messages
71
Re: HOW to remove old gas from internal gas tank

thanks again for the great responses.

i ended up draining the fuel this weekend.
threw on a bulb fuel line before it hits the f/w separator and let it drain out into several 5 gallon jugs.

it worked great.
time to burn it on the mower
thanks dualie
 
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