1997 355 Aft Cabin aux tank

[True-North]

Like many, my aux tank sat empty for many years and I wanted it back in service. I installed a spin on fuel/water separator/filter in the fuel line just upstream of the UFO fuel filter. Approximately 6 tanks of fuel and a dozen fuel filters later, there is some sort of green substance that won’t go away in the fuel. I know it can’t be algae, but it’s something like that. I just poured Starbrite fuel enzyme in there, and it seems to be working because I’m going through even more fuel filters and now the fuel lines are clogged. Has anyone gone through this process? I’m going to replace the one-way check valves at the fuel tank to see if that’s where the clog is. Anyone who has experience with this, please advise.

[bud37]

By any chance does the fuel you have put in that tank have any ethanol in it ?

[tomschauer]

Have you previously used the aft tank? If not, these had a crazy high failure rate for several years. Mine was replaced when the boat was only a couple years old.
If you never used it since you owned it, a previous owner may have tried some crazy sealant, or put something in there to prevent the tank from being used or to absorb the fuel smell.

[mjk1040]

Decommissioned mine 2 years ago due to suspected leaking. $7k -$10k replacement cost as the swim platform needs to be cut open to replace it, and if I was to replace it I would like to have a swim platform hatch built out of the cut out so one would have access inside the swim platform in the future if needed.

[True-North]

Non ethanol has been used in this tank to my knowledge. Certainly not in the last 13 years we’ve owned it. The tank does not leak or emit a fuel smell. It seems fully in tact. As previously stated, I have run about 6 tanks (720 gallons) of fuel through it in the past few years with no issues other than the clogged fuel filters.

[bud37]

Source of the post Non ethanol has been used in this tank to my knowledge. Certainly not in the last 13 years we’ve owned it. The tank does not leak or emit a fuel smell. It seems fully in tact. As previously stated, I have run about 6 tanks (720 gallons) of fuel through it in the past few years with no issues other than the clogged fuel filters.

That certainly is a fair amount of fuel you have put thru there, clearly you would think that after that, all would be well.....but something happened here and what you are seeing seems like tank residue getting cleaned up.

Quite honestly, if it were mine I would decommission that tank again and let it lie.

[True-North]

I’ll admit, I’m a bit of a nut in that I want this boat to run and work the way it did when it left Polaski, WI in 1997. I’ll keep you all posted after I change out the check valves. I suspect there is debris clogging them. I’ve hade to clean them before due to corrosion. They are easy to disassemble and clean with a Scotch-brite pad.

[mjk1040]

Come to think of it, when I was using the back aux tank, I too got a lot of rust and debris in my orburg filters. The thing is if you do not religiously switch to using the aux tank, I feel your going to have issues with debris from that tank do to lack of use. The other issue is gas today does not seem to maintain it's freshness as gas use to. FYI, saw a water removal video that tested different additives and found Heet to be the best on the market today in removing water. I also use Sea Foam (WalMart's Brand) which also seems to help get the crap out of the tanks and to the filters. Ah the fun of boating!

[buster53]

When it's comes to the aft aux tank, either completely empty it or use it on a regular basis. What I do, if I take a trip, that will use, say 100 gallons, I run both engines off the aux tank to get there and use the saddle tanks to get home. Doing it this way, I quickly use up gas in the aft tank which lightens the weight in the butt end of the boat.

[km1125]

Source of the post When it's comes to the aft aux tank, either completely empty it or use it on a regular basis. What I do, if I take a trip, that will use, say 100 gallons, I run both engines off the aux tank to get there and use the saddle tanks to get home. Doing it this way, I quickly use up gas in the aft tank which lightens the weight in the butt end of the boat.

I think that's a great policy for using a single aux tank like that.

It would be great if there was a second "fuel transfer" pickup that went all the way to the bottom of the tank so you could pump out the remaining fuel to one of the other tanks (though a filter) to completely empty it.