Best way to clean out a gas tank

[fbaxter3471]

I have a 2000 Proline CC 21ft, it sat aon a boat lift for 3 years without being ran, during that time the sending unit on top of the gas tank corroaded and allowed water to get into the tank. Over time the tank filled with a mixture of gas and water. I have drained the tank, changed the sending unit, changed the lines and had all the annual services performed along with the carbs rebuilt. My problem is there is alot of sediment in the tank, the bulb keeps collasping on WOT due to suction on the pick-up. I have ran seafoam and other stuff through the 70 gallon tank. Im not removing the tank so thats not an option, its in good shape, but how can I clean this tank out to get whatever is blocking the pick-up valve. I have already taken the sending unit off and siphoned all the gas/water out and then stuck a small shop vac hose down in and tried to suck the remaining, but I can't see the end of the hose due to the small hole I can only judge. Any suggestions would be appreciated.

 

[Chris1956]

Re: Best way to clean out a gas tank

Stop using the shop vac! The sparks can easily ignite gas fumes.

Will the sediment stay in suspension in water? if so stick a garden hose and a siphon in the tank and spray water to stir up the sediment and siphon it out at the same time. When she is clean, siphon out all the water, stick a rag in there to get any residual water, and add some denatured alcohol to get the final drops of water.

 

[fbaxter3471]

Re: Best way to clean out a gas tank

Dont think a rag is going to fit, we are talking about a 1 inch diameter hole here. And I have already siphon out with hose but not much sediment comes out, when I empty my water separator after running, thats when I see the most. Do you think it would hurt to take off the screen on the pick up valve, being I have a water separator and glass filter before the bulb and then a plastic inline filter after the fuel pump do you think I should remove the screen and let the sperator and filter do the cleaning for me.

 

[stackz]

Re: Best way to clean out a gas tank

70 gallon gas tank is going to be very hard to clean inside the boat itself. its probably got a long narrow flat spot on the bottom depending on how its molded to fit in the bilge area.

we had a similar problem on a 24' wellcraft. in the end, had to pull the tank and set it at an angle on cement slab and just shoot pressurized water inside to get at all the sediment with the tank turned in such a way that the fuel filler opening was at the lowest point. then we set it under an awning for a week to let it air dry without getting rained on.

 

[Chris1956]

Re: Best way to clean out a gas tank

Your water separator and it's associated filter will do the cleaning for you. You can remove the pickup screen.

You need to be dilligent and purchase a couple of filter elements, and always have one with you in case it clogs while underway. However, this may take a long time. Can you scrape the bottom of the tank with a long handle wire brush? Maybe the kind used to clean long test tubes or pipes, bent in the middle. if you can get the stuff loose, it will go the the filter in one tank of fuel.

 

[CharlieB]

Re: Best way to clean out a gas tank

If the primer bulb is being sucked flat then there is often a problem with the fuel pick-up tube or the tank fitting/check valve restricting full fuel flow. Have you pulled the dip tube and inspected it and the fitting?

 

[fbaxter3471]

Re: Best way to clean out a gas tank

the pickup tube is clear and fine, the pick up is fine, I alot of sediment in the tank, problem is at wide open throttle the bulb collasps because the suction is so great, if I run half throttle do have the problems. I empty the separtor every time I go out in a glass jar and when the sediment settles its usually about a 1/10 of an inch thick.

 

[j_martin]

Re: Best way to clean out a gas tank

If you're getting that much crud in the water glass, the finer stuff is plugging the filter part of that unit. You need to change the filter more frequently.

I know the filters ain't cheap, but about the quickest way to burn down a 2 cycle outboard is to starve it.

 

[fbaxter3471]

Re: Best way to clean out a gas tank

Yes Admiral, I am changing the filters quite often, actually after everytime I go out. Im using the quicksilver water separators and they are only about $10 and the glass filter I have has screen replacements that are only a couple of bucks. What do you think about the idea of taking the screen off of the pick up tube and letting the filters clean the tank for me. I been told by my mechanic that he doesnt even use a screen on any of his boats. Feedback appreciated.

 

[Jerryragon]

No Title

too difficult to remove tank. I flushed the tank with 5 gallons of acetone continuously for 3 hours and changing the filter 4 times. It looks like a new tank now.