How do I clean gas tank

[harrisg]

My carb for my AQ125a/270 finally arrived at the rebuilder. He called me and said that because the boat had been sitting for 4 years and had old gas, that it was important for me to clean the tank to get the crud out. Otherwise, having the carb rebuilt won't help in the long run. Only problem is that I can't get the tank out without tearing out a bunch of things in the stern section. To start with, I've installed a fuel filter/water seperator and will install another fuel filter downstream from that. The tank is stainless steel and I'd appreciate any feedback on methods for cleaning.

 

[RandyJ]

Re: How do I clean gas tank

I have taken a couple of tanks to my local radiator shop for cleaning and coating the inside. If you've got a stainless steel tank I don't think I'd get crazy about cleaning it...but you do not mention if it is used in salt-water or fresh water and I'm not familiar with salt water usages. The only methods I know of for cleaning fuel tanks is either chemically or put gravel in them and shake it around...then you've got the problem of getting the gravel out and washing the tank...of course that's for rusted tanks. I would ask for suggestions from a few reputable auto parts stores or old timers in the boat business before I started jerking out a big fuel cell.

 

[harrisg]

Re: How do I clean gas tank

I don't know if it was used in salt water previously but if it was, it was a small part of it's use. It appears to have been used mostly in fresh water. The problem I have is that removing it doesn't appear to be an option because of it's location. Is it possible to do a cleaning of a stainless steel gas tank in place? I know this sounds stupid but is there anyway to vacuum it with a long thin hose? Am I reaching or what?

 

[RandyJ]

Re: How do I clean gas tank

Can't speak intelligently about that but basically, a siphon hose is going to vacuum it. If you are not having problems with crud stopping up the fuel line I just don't think I'd worry about it if ya got a decent water separator and a good filter. I have no idea what a AQ125a/270 is...but I'm sure it has all the common maladies of other money pits in the water.

 

[kfraser]

Re: How do I clean gas tank

I'm facing the same problem with a project boat I just purchased. It has a 35 gal under the floor stainless tank. I've removed all of the flooring, so I can remove it if necessary. It had a half tank of fuel when I bought it and it has been sitting since 1991. The gas had the color of a pot of strong coffee. Drained the tank, replaced the fuel filter and water separator. I talked with a tech from my local mercruiser dealer and he said fill the tank completly with fresh gas and add Stabil gas treatment. He said to change the fuel filters after every hour of use for the first three hours. He said because the tank is stainless, it would not have the rust/big particles problems of other tanks. I'm rebuilding the carb tomorrow and will run her this weekend. I'll let you know if this works for me.

 

[Dunaruna]

Re: How do I clean gas tank

If you have reasonable access through the sender unit hole you can pressure wash it internally, then dry it out. Disconnect all hoses, remove sender- stick nozzle of pressure washer into hole and blast away. When your finished, syphon out as much water as possible and then let air dry or get in there with some rags and mop it out (if the sender hole is big enough). There is another way to dry it out 100% but I'll be dragged over the coals if I told you.

 

[rbezdon]

Re: How do I clean gas tank

If you have that access through the send, look inside the tank and see if you can see how bad it is. My boat sat for a couple of years with a half tank of gas and all I did was remove the antisiphon valve and attach a long hose from the gas tank piuck up out through the bilge and the boat drain plug hole and siphon the old gas out. I looked in the tank through the sender hole and there wasnt a lot of crud so I just put everything back and filled it up with 35 gallons of fresh premium and some gas treatment. I figured if the siphoning left a quart of the 4 year old stuff in there diluting it with 35 gallons of new pretty much made it a non-issue. I also changed the gas filter and seperator after a couple of hours but there didnt seem to be anything in them. Since it was only 4 years, I bet this will be good enough, unless of course, you see some of that strong coffee colored stuff and the smell of it is very obvious as well.