Fuel conditioner/biocide

[Ken Krawford]

I tend to use my engine very little and as a result the fuel in my tank lasts a long time.  When I look at fuel additives, it seems they are either biocides or cleaners.  Under my circumstances, I assume a biocide is more important.
Is there a product that has both?  What brand is best?

Thanks.
Ken Krawford

[Mark G]

I am finishing (unfortunately) my first season with a '91. Previous owner used the engine for in-and-out of the Milwaukee harbor to day sail most of the time. Never ran the tank low. Never out in really rough stuff to stir things off the bottom. I ran into a fuel problem on the other side of Lake Michigan.

The mechanic's first response was that my fuel was old and full of additives plus I had water and gunk in the bottom. When the tank rarely empties, old fuel and additives build up over time. What you dilute at fill up is worse and worse. Even with half a fresh tank added, the fuel was more yellow than red. I pulled out the panel in the aft cabin and had the tank pumped dry with a siphon that reached to the bottom.

Forum owners told me to do this when I bought the boat. I listened to the dealer instead of the experts here. A big mistake that I was fortunate to catch in the harbor and not 40 miles off shore.

My advice: pump it dry. Change the filters. Clean the screen in the pump. Start with fresh fuel. They told me to use a conditioner to keep water out.

[Ron Hill]

Ken : We've had quite a number of posts on this topic. Look at them.

Seeing the age  of your boat here's what I'd do.  Drain the fuel out of the tank using the electric fuel pump in to fuel jugs.  Then remove the tank and clean it well.  Change both fuel filters.  
If you look in the tech notes and projects you'll see how I did this.  I'd dump your fuel, but if you're frugal reuse it as it should be filtered clean going into the jugs.  Don't overdo it with additives.  Look at the bottle - I use the one with the most ACTIVE ingredients!!

BTW, you always want to get your engine up to operating temp. and then run it there for about 15/20 minutes.  Diesels like to be run.

You might want to brose thru Frequently Asked Questions, Tech Notes and Projects on the C34 web Site as there's 19 YEARS of information there.  You're not the first one to encounter this problem.  

[Steve Hansen]

I recently took a class on marine diesels offered by Chesapeake Marine Trade School. Their recommendation for the biocide was Biobor. They did not advocate fuel stabilizers. Also to make sure the bowl of the water separator is clean so the fuel can be easily viewed for water and check regularly. Plenty of great advise on this message board too

Steve

[captran]

After years of reading all the horror stories of the gunk in the bottom of the tank I am aware of that issue.  Voyager is a 1997.  I use Biobor on Voyager for 5 years.  Change the filters annually in the spring.  5 summers full time in the tropics, then storage for 10 months between summers.  Have never had a problem.  Used Biobor in the NW for 7 summers on a Newport 30, also with good results, and Voyager is now in the NW.

[Stu Jackson]

We use BioBor and also Starbight water separator.  No problems in 7 1/2 years.

[Ron Hill]

Like I said you can pay many $$ for those "inert ingredients".  

Be cautious of the water absorbers for diesel that have alcohol in them.