Water in gas tank - what now?

[Smokey]

My boat has a snap-down fuel cap located at the back of the boat. Apparently I did not get it snapped securely when I filled it this spring. While it was sitting on the lift during a large storm May 22, waves broke over the back of the boat and filled the remaining space in the tank with water. I'm guessing that I have 18 gallons of gas and 1-2 gallons of water in the tank right now.

I had a clear flexible tube, so I tried to siphon off the top, then the bottom, or as far as I could get the tube to go, trying to get rid of most of the water. I don't know if the water will be at the top or the bottom of the tank.

I then started the engine and let it run at a fast idle, it's a 3 liter I/O. After minute or 2 the sputtered and died, and now it tries to start and run, but keeps dying.

Can I pour in some seafoam or something like that to absorb the water? The boat is a 1995, so I don't want to use anything with alcohol in it. Or do I need to drain the tank and lines? That sounds like a big job.

[SandBayFishCamp]

Draining shouldn't be too difficult and that is probably your best option. Especially if you have as much water in the tank as you estimate. I have a siphon attachment that actually hooks up to my cordless drill...you can probably find them online. Use gravity to your advantage...

[Ralph Wiggum]

The water should be on the bottom, if I remember correctly. If you could siphon most of the water out, then a bottle of HEET or Seafoam should take care of the rest of the moisture. It would be a shame to get rid of 18 gallons of gas!

[marine_man]

Water will be at the bottom - gas / oil is lighter than water.

I'd siphon it all out, fill it up with new gas and a bottle of heat for insurance.

marine_man

[Gordie]

I would not put heat in a outboard I have seen one blow up because of that it was a two stroke it might fine for a four stroke thou. I would drain and rinse out with a gallon of gas then fill and put a bottle of sea foam in it.

I have had to do just what I said to do and it works very well.

I see thats it a I/O but still wouldnt put heat in it

[walleyemaniac]

I'd drain it, put in fresh, and add some seafoam for added insurance. You've still got to get all the water out of the lines and carb from when you tried to start it. Even with fresh gas it will probably run like [PoorWordUsage] for a little while, unless you drain the carb and everything first, you still have to get good gas up though all of that. Boat motors always seam to be more fussy.

The water should go to the bottom but it will take a long time for all of it to settle out, especially if you've been bouncing around in the boat it's been shakin up in the tank.

I worked for a place that got water in their underground fuel tank because of a leak in the tank. They pulled a bunch of fuel off the bottom and four weeks later they were still draining water out of the storage tang they put it in. It won't seperate over night.

[Smokey]

I am going to stay away from the heet/isoheet, and stick with seafoam. My plan for the weekend is to try and siphon out the bottom 5 gallons, since I have an empty gas can that size. I don't know if I can get the end of the siphon down that far thru the filler tube, so I am going to pull up the floor panel above the tank to see what I can see.

Then I'll add a can of seafoam, maybe 5 gallons of good gas as well, and try to start it. I'm regretting starting it last weekend since that means that now I've pulled the bad gas all the way up to the carb. I may need to do a squirt bottle of gas in the carb trick to keep it running until it gets past the bad stuff.

And keep the fire extinguisher handy.

[Smokey]

walleyemaniac,

I guess we were thinking the same thing. I had started the reply about 45 minutes ago and then had to leave my desk for a while. Darn jobs get in the way of the important stuff.

Came back, finished up, hit submit, then see that you had pretty much said the same thing.

[SkunkedAgain]

You really should drain the whole tank. If you were one of us, providing advice, you would likely say the same thing. I know that it sucks to get rid of that much gas, but just think of how much you'll hate yourself for killing your motor because there was still a bunch of water in the tank. Do yourself a favor and suck it up by dragging your boat onto the trailer and having a repair shop to it the right way. A couple hundred bucks for a tank drain is much better than a costly motor repair IMO.

[barebackjack]

2.50 a gallon is a world cheaper than what your expenses could be running water through your motor.

[Eelpout08]

I would also drain the tank, gasoline will absorb a certain amount of water, especially if it has ethanol in it, even if you dilute it with fresh gas you will probably have performance problems from whatever contaminated gas is left. the good news is you dont have to waste all the 'bad' stuff. let it sit in a can for a while then siphon out the bottom where the water is then put the rest in your truck a gallon or two at a time, a vehicle can handle more water in the fuel then a boat motor. i do this routine every fall with the snowmobile.

[Down Deep]

Most repair shops, especially the ones that repair large vehicles, will be able to pump the tank for you. You may even find one that has a separator. Sea Foam is an additive not a cover for water.

[Smokey]

In case anyone is wondering, this is what I ended up doing.

Bought a "water separator" funnel ($25), a hand pump ($10), and a can of seafoam ($7) from a marine supply store.

Disconnected the fuel line from the input of the fuel pump and connected it to the input of the hand pump. Ran the output of the hand pump through the separator funnel into an empty 5 gallon gas can.

The first gallon pumped out was mostly water, by the time I got to gallon 5 it seemed to be all gas.

I then reconnected the fuel line and dumped in the seafoam.

Then I took the flame arrestor off of the carb so that I could squirt good gas in as needed to keep the engine running. I'm not saying this is a good idea, it's just what I did.

After about 10 minutes of squirting, starting, and dying, the contaminated gas seemed to be out of the line between the fuel pump and the carb. After it was able to idle for a good 10-15 minutes with no help from me, I took it off the lift and onto the lake.

It still hesitated a bit the first couple of times that I tried to accelerate, but after another minute or 2 it was running like a top.

In theory I should be able to dump the filtered gas back into the boat, but I plan to mix it in to the 44 gallon tank on the Suburban instead.

[Ralph Wiggum]

Sounds like you had a good plan! Glad to hear it worked out for the best.

[propster]

I ran into a guy up north last Sunday who left his boat on the water overnight during the 4.8 inches of rain the area got Sat night. His gas cap was tight, but he's thinking the water got in through the vent on the side of his Lund. Anyway, he knew he had at the most half a tank before the storm, but it was full after! He made the mistake of starting it also, and it ran abit then died. His was a fuel injected motor. What could he have done to remove water from that engine? (in case it happens to me someday!)

[Fisherman45]

If you aren't totally draining the tank you are in for trouble that's pretty much all there is to it. For what we pay for these motors better to do it right then half arsed and save a little time.

[solbes]

I'm SOOO glad I pulled my boat all the way onto the lift that Saturday night. It rained like crazy up north, washed out our road, etc.

Anyway I had a problem with a bad batch of gas in the past with my old 2s motor and boat. I hadn't diagnosed it myself, the dealer did. They drained it for me without asking and charged me $300. Pretty ridiculously steep, but the boat ran like a top again after that. I certainly wouldn't balk at the lost cost of the contaminated gas.