Draining old fuel

Loyd Dinneen

Active Member
Jul 29, 2017
484
Las Vegas
Boat Info
1977 Sea ray 240 SDA cruiser w/ twin 470 mercs.
Engines
Twin 470 Mercruisers
Has anyone tried removing old fuel from a boat? I have a 1977 Searay 240 srv 24ft Sundancer with twin 470 mercruisers. I have been working on it for a year or so and it has about 40 gals of fuel in it that is a year or so old and I feel it is most likely gone bad by now.
 
I have had older fuel without stabilizer where I drained half the tank into Jerry cans. I then filled the tank with fresh, mid grade fuel and ran the boat. Zero issues. Then use up the other half from the cans. You may want to change gas filters afterward.
 
Has anyone tried removing old fuel from a boat? I have a 1977 Searay 240 srv 24ft Sundancer with twin 470 mercruisers. I have been working on it for a year or so and it has about 40 gals of fuel in it that is a year or so old and I feel it is most likely gone bad by now.
If you're sure you want to get rid of it, you can use an electric fuel pump to pump it out.
 
To pump that much fuel all at once would burn up an electric fuel pump, I have a syphon hose system that I can use if I go thru the fuel sender hole and just haul the fuel cans up out of the cabin. Thats one plan.
 
To pump that much fuel all at once would burn up an electric fuel pump, I have a syphon hose system that I can use if I go thru the fuel sender hole and just haul the fuel cans up out of the cabin. Thats one plan.
Use an inline fuel pump (designed for continuous operation) and certainly ignition protected so no spark issue. The flowing fuel keeps the pump cool so it does not burn up. It works fine. I've done it. I'd do it outside from the fill pipe where fumes can dissipate, not inside the cabin. Quick and easy.
 
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If it is ethanol free fuel it will be fine even with out stabilizer. Just a thought.
 
I drained about 25 gallons from ours. It had sat about 3 years and the ethanol had separated. Left us stranded a couple of times. Drained it and rebuilt the carb and it ran great after that. I used a shaker hose with a check ball and then towards the end I used my oil change pump bottle. Worked great
 
Use an inline fuel pump (designed for continuous operation) and certainly ignition protected so no spark issue. The flowing fuel keeps the pump cool so it does not burn up. It works fine. I've done it. I'd do it outside from the fill pipe where fumes can dissipate, not inside the cabin. Quick and easy.

This works well but it is slow. We have a jetboat and have two 25 gallon spare gas tanks. To move the fuel to the main 75 gallon tank I set up a car electric fuel pump with a cigarette lighter plug on it and 20 feet of gas line hose from the spare tank to the filler cap of the main tank. Pump rate is around 1GPM.
Gas is good for 2 years without much deterioration. Jet boat sat for 3 years once and fired up on old gas.
 
Removing the gas is not the problem disposing of it is. Year old gas will work fine in your car after you remove it from your boat.
 
Removing the gas is not the problem disposing of it is. Year old gas will work fine in your car after you remove it from your boat.
I mix old gas with old motor oil and use it to get a brush pile ignited when I clean up around the property. The oil keeps the gas from putting off so much vapor.

Our local recycler will also take gasoline oil mixed.
 
I have used sour gas mixed with good gas to run in my truck, truck ran on it but not real well overall.
Good tip on mixing it with oil for the recycler I have a bit of left over oil that I can get rid of.
 
I had about 35 gallons to get rid of. I pumped it into a blue plastic 55 gallon drum that anti freeze comes in. They are probably free at your boat yard. I left it outside in he sun in the corner of my open lot with the bungs open and a fish tote sitting on top so rain won’t go in. A year latter it’s all evaporated.
 
I had about 35 gallons to get rid of. I pumped it into a blue plastic 55 gallon drum that anti freeze comes in. They are probably free at your boat yard. I left it outside in he sun in the corner of my open lot with the bungs open and a fish tote sitting on top so rain won’t go in. A year latter it’s all evaporated.

I’ve done that in a smaller scale and it worked perfectly.
Another option that I helped a friend do:
He had about 40 gallons of 2 year old fuel to remove, we used a 12 volt electric pump and put it in a bunch of 5 gallon gas containers.
He brought one to the gas station with him every time he filled his truck up, poured it in the empty tank, topped off with fresh gas from the pump, and all was well.
With regular weekly fill ups, it was all gone and put to good use in two months.
 
That's definitely an option , looks like I will have to get a few more containers, 12 volt pump, some fuel hose and some ambition.
 
That's definitely an option , looks like I will have to get a few more containers, 12 volt pump, some fuel hose and some ambition.
Before you get fuel hose, try a long piece of hanger wire with a tight loop on the end. Just to see if the fuel filler hose is fairly straight to the tank. If so, 3/8" fuel hose should go in, too. If not you may need 5/16" to better follow the bends into the tank.
 
If I remove the cushions in the forward bunk area and then take the starboard panel off the fuel hose is exposed and it comes down and makes a sweep to the filler neck. The fuel tank, sender, and hoses are easy to see with that area cleared out.
 

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