Fuel Tank Deposits Question

[redsky49]

Planning to head over to the Bahamas for a few months - out of curiosity I peaked into one of the two fuel tanks I have. I suspect the situation is the same in the other tank.

I have black deposits on the wall of the tank, which is very difficult to remove. I suspect this to be asphaltene.

My question:
Can I leave this for removal at my planned summer haul out, or will this cause me problems?
Should I start to use a fuel additive?
Should I purchase a case of filter replacements?

Anyone have an authoritative opinion/advice?

[redsky49]

And the plot thickens! As does my fuel.

Here is the generator primary filter. Not the worst I have ever seen, but clearly affected.

And the fuel looks darker than it should.

Looks like I am going to empty the tank(s), clean, refill, replace all filters and start fresh.

Rats!

[Paul L]

How many hours on the fuel filter?

[a64pilot]

Of course buy a case of filters, you should have that anyway, don’t forget the final filter on the engine too.
Go to the Bahamas, have fun, this will pass. There are millions of boaters, like me that have never seen the insides of their tank, and mine is 30 years old.
I think your correct about it being asphalt, if so maybe ULSD over time will strip it off, and of course it’s going to be in the filters if it does.
Yes run a fuel additive, a bug killer, I like Biobor JF, but there are others.
Always run it, period.

[redsky49]

I think the hard coating of the tank sides may be asphaltine, but there was more.

I emptied the tank and found a glob of blackish shmoo on the bottom of the tank. This certainly looks like the algae/bacteria/bugs that I have seen before. Certainly surprised to encounter this using US fuel. Since I had previously only encountered it outside the US, I was not vigilant here in Florida. That is my fault.

The filter has about 50 hours. The fuel however, is at least a year old. Haven't been using the generator much lately. The fuel definitely looked 'off'.

Attacking the sludge with a ScotchBrite pad and some Dawn dishwashing soap made (laborious) progress, but I can't get past the tank baffle to access the rear of the tank.

Is there a tool that will fit through the baffle openings, something that uses a drill, like a duct cleaner or chimney sweep? And if i don't clean the back of the tank, is all my effort in vain?

[a64pilot]

Not all US fuel has a bio additive and will grow “bugs”.
Valvtec I believe does, however I always add BioBor, it does no harm.
Some additives claim to add lubricity, something that the new ULSD is lacking compared to the old high sulphur fuel.
I’d say clean as much as you can, cause what else can you do? However I believe it will eventually pass thorough and the filters will catch it.
Others will tell you you need a fuel polisher. I don’t believe they are necessary, can’t hurt, but in my case the money can be better spent elsewhere.

[Compass790]

I had a heap of black crap in my tank that seemed to come off washing it out with petrol ( gasoline ) but cant say if it was the same substance as yours. Try a vicious degreaser maybe if petrol wont shift it..After I did it changed filter after 50 hrs & then next one done maybe 300hrs & still good.I use a filter funnel when tank filling tho & burn only 1.25 litres per hr.

[Uncle Bob]

Hi, been there done that,didn't like it!
Asphaltenes were responsible for most of my fuel woes previously, along with some bug. Fuel additive solved the bug issue and repeated filtering of the fuel on board along with the installation of dedicated sedimenters prior to the primary filters has so far been totally successful (touch wood ) Possibly the replacement of crap fuel lines of differing sizes with lines of 8mm copper with radius bends and no 90deg fittings helped.
My tanks are integral and have no access other than an additional filler fitting in the top of the tank so a thorough cleaning was not possible.