Fuel Tank flushing/cleaning

[Jeepinvusa]

Hi All,
My 18ft CC has a plastic fuel tank thats about 30gals. The tank cannot be removed due to it being installed under the floor. I can see some of it but not all. The tank is currently 3/4 full with old gas/oil mix (2stroke), water, and salt water (previous owner capsized it while being towed). There is no water separator installed either. I believe the contents of the tank has been there for more than 6-8months. What can i use or do to get is all flushed out and very clean? I can siphon the curent content out... thats not a problem.
One boat shop told me to run just e-10 gas through it a couple of times... that the ethenol will destroy it all??? Should i do that 2-3times with 10gals of fuel each time and drive it through bumpy roads?!?! and siphon out?

 

[David Greer]

Re: Fuel Tank flushing/cleaning

On the trailer: disconnect your fuel line at the motor, drop it into the bilge and run it out thru the drain plug to drain the tank.
Good luck disposing of the old stuff. Try the fuel cleaning companies; they may let you bring it to them for a fee. They will also suck out your tank for you from the trailer. Do not let them clean and return it!

If you do it yourself, after it's empty, use carb cleaner to clean the tank. If yo can reach inside it use newspaper to swab it. Then flush through with fresh gas. When your guy said "run some e-10 through it" I hope he didn't mean run it through your motor!

Raise and lower the bow w/ the trailer jack as needed, but remember the fuel pick-up likes it level.

If the tank is fiberglass you have no option but to replace it.

Be sure your fuel line is cleaned, too, and put in a seperator (if you can use them on premix?)

 

[Jeepinvusa]

Re: Fuel Tank flushing/cleaning

With carb cleaner? how? Just spray it down the Fill cap? Do they sell it in gallons? I really dont know.
When the boat shop guy said "Run some e10 through it", he meant just regular gasoline that has e-10 only through the tank... not the motor. Besides, doesnt all fuel now have e-10 mixed in already??

 

[David Greer]

Re: Fuel Tank flushing/cleaning

yes almost all gas is e-10 now.

you should be able to get to the pick-up and/or the sending unit through a deck plate. Are you sure you can't unscrew the whole deck? Once you get to an opening like that you can spray carb cleaner all in there. There might be a liquid that's similar. if you can't get to the tank at all, either consider cutting the deck out and replacing, or returning the boat to the guy who swamped it.

My 1988 Key West was the first model year, and when the alum gas tank sprung a leak, we found it couldn't be lifted out--the boat was basically built around it. We ahd to take it out in chunks. the replacement, however, had a slight bevel to the bow end and it dropped right in, with part of it under the bow deck. Still had to chop out some of the bow deck locker interior but the patch is out of sight. Not the only hole we had to cut for access.

 

[Jeepinvusa]

Re: Fuel Tank flushing/cleaning

yes almost all gas is e-10 now.

you should be able to get to the pick-up and/or the sending unit through a deck plate. Are you sure you can't unscrew the whole deck? Once you get to an opening like that you can spray carb cleaner all in there. There might be a liquid that's similar. if you can't get to the tank at all, either consider cutting the deck out and replacing, or returning the boat to the guy who swamped it.

I have access to the Sending Unit... so i'll get in there and spray it all down. Does carb-cleaner just eat all the bad out?!?!? The only other way to get the tank out would be to take the entire shell off the hull. How does that one method work for draining the fuel that you mentioned earlier? Just run the fuel line back into the boat... then down the bottom of the hull and out the plug hole.... the it will just drain automatically by gravity? The only other way i know of besides using a pump, is by the primer and get a rediculus fore-arm workout!

 

[David Greer]

Re: Fuel Tank flushing/cleaning

Use the primer and once you get it going, if your jerry can is on the ground, the siphon effect will keep it flowing. Or so I've heard; I have to dump 18 gallons from my tank sometime this spring and this is how my mechanic told me he did it before.

Sad thing is--the gas I'm dumping is mostly what I bought last summer at $4/gallon. Damned ethanol and the idiots in Washington!

 

[Mark42]

Re: Fuel Tank flushing/cleaning

You got a lot of options and good advice so far. Just let me add my 2 cents:

If the gas is gummy, it will probably gum up the screen on the pickup tube in the tank. I suggest removing the sending unit, and drop in a length of 3/4" vinyl hose from the hardware store and syphon it out. This is how I empty my tanks for the winter (except I put the hose down the fuel fill). Then you can see what is left in the tank. If you need to wipe down the inside of the tank through the sending unit, it will be difficult. You can't fit your hand through that hole, but you can use a length of bent copper tubing or the like. Also unscrew the pickup tube and clean off the screen. Leave it out while you clean so you don't accedentally bend/crack or break it off inside the tank.

I would not be too surprised if the tank is not very dirty. After syphoning empty, dump in a gallon of alcohol (from the hardware, its cheap) and slosh around with a rag on a stick through the sender hole. Then syphon out, repeat until you think its clean enough to put gas in.

Get a water separating filter like this one form Moeller Marine (much less expensive than Racor, and just as effective at removing water and dirt). Similar unit sold by Sierra (same item repackaged). Its nice because it has a water drain valve at the bottom. Note the clear bowl units are only legal on outboard motor boats. Inboard must use the metal bowl version.

 

[gss036]

Re: Fuel Tank flushing/cleaning

I go along with MARK on this idea. I have a Honda/Racor (small one, 30gph, 10micron) and it saved me last week. All of a sudden all the junk in my 115 tank
must have broke loose as I was running in rough water and the filter clogged up to the point that it SUCKED the primer bulbs flat killing the engine. So, YES, they do work. I was able to drain the contents out the bottom get the 225 Honda running again and made it back home.

 

[David Greer]

Re: Fuel Tank flushing/cleaning

carry a spare filter in a ziplock for this reason (zip lock to dispose of old one and more important its contents)

 

[Jeepinvusa]

Re: Fuel Tank flushing/cleaning

wow... plenty of help! you guys rock! thanks a million for you all.

 

[gss036]

Re: Fuel Tank flushing/cleaning

David, I did have a spare filter, but did not need it at the time due draining the bulb and I was in really choppy waters, not the beast time to change out a filter.