Diesel bugs. Do I care?

[Skipper]

I've had the boat 5 years. Last Racor filter change back in March, I decided to also remove and disassemble the housing because it looked cruddy. It turned out to be an awful mess. The whole apparatus was full of gunk. A thin sludge, like someone didn't stir the cocoa very well.
It had been 2 years and 100 hours since filter change. And in reality probably 200 hours since I first noticed that the glass was a little foggy (I had drained it so assumed it was just stained - wrong).
However, no problems with the motor. Secondary filter showed crystal clean fuel.
So I cleaned it up and reinstalled.
Now 60 hours later I'm doing RM today and take apart the Racor because it's getting dirty again. Not nearly as bad this time.
So I figure there's bugs in the tank.
However, never a twitch from the motor. No fuel problems ever. And I use the boat a lot. Nearly every weekend plus cruising trips.
I use Star Tron every fill up. Which I think has minor anti-bug qualities.
Do I bother with a tank cleaning?
I also bought bug killer but haven't used it yet.
By the way I have a high tech fuel gauge - a dowel rod inserted at the deck fill in the cockpit floor. No access hatch or sender. When I measure the level, the dowel hits the tank bottom with a good clunk, no sludge sound.
Any comments appreciated.

 

[kloudie1]

The only thing that you are risking is a motor shutdown at an in-opportune time. It has not plugged enough to shut the engine down yet; doesn't mean that it won't, especially after or during heavy seas when stuff from the sides/top/corners of the tank get stirred.. This is a lot worse at low tank levels because the concentration of smutz to diesel goes up and the stirring action from waves will go up at the lower levels.. Your risk is not too high if you are getting 60 hours or so on the filters, but if you sail with low tank levels in rough conditions, the risk will go up. A second primary filter, set up so you can shift between the two, might be a benefit if you really don't want to clean the tank.

 

[Alansails]

We use Biobor JF to add Bugs and the diesel we buy has Valvetech already added. we add a little DIESEL Shok
when the spring launch/mid season and end of season.

 

[capta]

Startron makes a tank cleaner as well as the fuel additive. You might want to try that before you spend the big bucks on having the tank professionally cleaned. I believe you will need to change filters very often after doing this.
If you are using the additive regularly, in the correct amounts, I don't see why you are still having this problem, unless it is something else. Do you have an aluminum tank?

 

[Gunni]

The Biobor JF contains the pesticide that will kill the bio-growth, but you still need to get it out. Startron contains additives to stabilize the fuel components. You can either keep changing filters with great regularity or find a way to open the tank and have it cleaned. That may mean multiple openings if the tank is baffled. I'm not a fan of the "fuel polishing" thing.

 

[Benny17441]

The first thing I looked after reading the post was to see if you sailed in a lake. It is remarkable that your Racor filter has not clogged; how many Microms?

 

[Skipper]

The only thing that you are risking is a motor shutdown at an in-opportune time. It has not plugged enough to shut the engine down yet; doesn't mean that it won't, especially after or during heavy seas when stuff from the sides/top/corners of the tank get stirred.. This is a lot worse at low tank levels because the concentration of smutz to diesel goes up and the stirring action from waves will go up at the lower levels.. Your risk is not too high if you are getting 60 hours or so on the filters, but if you sail with low tank levels in rough conditions, the risk will go up. A second primary filter, set up so you can shift between the two, might be a benefit if you really don't want to clean the tank.

Hmm, that may be why no clog - I never let the tank get below 1/3.

 

[Skipper]

Startron makes a tank cleaner as well as the fuel additive. You might want to try that before you spend the big bucks on having the tank professionally cleaned. I believe you will need to change filters very often after doing this.
If you are using the additive regularly, in the correct amounts, I don't see why you are still having this problem, unless it is something else. Do you have an aluminum tank?

Yes aluminum. It's isolated with no metal contact.
I bought the biobor but haven't used it yet. Am thinking that a mass killing would bring the clogs. Have lived with bugs for 5 years and 300+ hours - it may be time to finally zap em.

 

[Skipper]

The first thing I looked after reading the post was to see if you sailed in a lake. It is remarkable that your Racor filter has not clogged; how many Microms?

I've always used 2 mic. Even when it had years of gunk it never clogged. Uses an electric pump to pull fuel through the Racor and out to the secondary.
It's an M18 2 cyl 14hp, which burns a measured .31 gph average. This slow flow rate may have been tolerating any hindrance.

 

[kloudie1]

Correct on low flow, Skipper.. That flow rate is 3.9 Teaspoons per minute through the filter.. actually probably more like 6 per minute because of bypass flow at the injectors.. Your contamination is not really bad but if you let the tank get down to 1/3-1/4 in a seaway, you could have a problem pretty quickly.. again sounds like no big rush to purge/clean, but if ya dose with Bio-Bar.. ya going to have a big kill off and things could get messy.. Good luck with it..

 

[Jim 5757]

FWIW I don't see why fuel level matters. Your pickup is at the bottom and I think the crud lives down there too. Bouncing around in waves should stir things up. When we first got the Merry Bee we knew nothing about this problem. On our 1st trip outside the engine died within 10 minutes. Primary was BLACK. We ended up pulling the tank to clean it out.
Metjinks that sooner or later you'll have to do something about this...

 

[Skipper]

Correct on low flow, Skipper.. That flow rate is 3.9 Teaspoons per minute through the filter.. actually probably more like 6 per minute because of bypass flow at the injectors.. Your contamination is not really bad but if you let the tank get down to 1/3-1/4 in a seaway, you could have a problem pretty quickly.. again sounds like no big rush to purge/clean, but if ya dose with Bio-Bar.. ya going to have a big kill off and things could get messy.. Good luck with it..

Thank you

 

[Skipper]

FWIW I don't see why fuel level matters. Your pickup is at the bottom and I think the crud lives down there too. Bouncing around in waves should stir things up. When we first got the Merry Bee we knew nothing about this problem. On our 1st trip outside the engine died within 10 minutes. Primary was BLACK. We ended up pulling the tank to clean it out.
Metjinks that sooner or later you'll have to do something about this...

Yup. I'll try the biobor with the tank low, then pump it dry with a hand pump. Hopefully can get the bulk of critters out, then fill it and keep an eye on the Racor.
-we have hazmat barrels in the harbor for disposal. Which is fabulous.

 

[jibes138]

Get some clean jugs and pull the return line off the tank. Fill the jugs until the tank is empty. This fuel will be filtered and water separated. Then put the hose back on the tank return. Pull the hose off the pickup tube and pump the fuel out of the jugs back into the tank, the fuel will now be filtered four times. If you start with just a quarter tank or so it shouldn't take too many jugs or time. Add a pressure(vacuum) gauge to your Racor.