Should fuel tanks be full?

[OldDan1943]

DonL My suggestion is to remove all the fuel, inspect and clean and Visually inspect the tanks then polish the fuel as it is return to the tanks. Also treating the fuel with a good stabilizer. Of course change the primary and secondary filters. You might have change the secondary filter if the boat undergoes some serious weather.
Keep an eye on the secondary filters to see what is happening.
You should give consideration installing a fuel polishing system.

Once you get all this done and you still see a problem, You have to ask, am I working on my boat or the neighbor’s boat. SMIRK
I cant think of anything else to do.

 

[Don L]

DonL My suggestion is to remove all the fuel, inspect and clean and Visually inspect the tanks then polish the fuel as it is return to the tanks. Also treating the fuel with a good stabilizer. Of course change the primary and secondary filters. You might have change the secondary filter if the boat undergoes some serious weather.
Keep an eye on the secondary filters to see what is happening.
You should give consideration installing a fuel polishing system.

Once you get all this done and you still see a problem, You have to ask, am I working on my boat or the neighbor’s boat. SMIRK
I cant think of anything else to do.

No need to give me "fixes". I only have a little "gunk" but know of boats that have had enough problem to plug up lines from tank to engine. My point was aimed someone who tried to say the problem doesn't even exist. But the "gunk" that ends up in bottom of my separator bowl proves that it does exist.

 

[Bonedoc]

Not yet discussed slightly off topic, and likely obvious to the experienced diesel operators is the issue of topping off your tanks and uneven fuel return to perhaps one tank causing overflow. Prior to “ topping off”- the diesel boat owner should know if the fuel returns to one or both tanks.

 

[OldDan1943]

No need to give me "fixes". I only have a little "gunk" but know of boats that have had enough problem to plug up lines from tank to engine. My point was aimed someone who tried to say the problem doesn't even exist. But the "gunk" that ends up in bottom of my separator bowl proves that it does exist.

Don L okay

 

[greatpapabear]

We have 2, 112gal diesel tanks. I haven't needed to put fuel in them for a long time. Both tanks are a bit over 1/2 full and racors don't show crud or water. Motor starts quick every time and runs great. We burn very little fuel and do use it at least 2-3 times per month.

- Is the consensus to keep tanks always full?

Hi,

It's a good question and one which can generate much discussion!

Since there's always been a debate about condensation in tanks, we chose the safe route and kept ours filled. The mantra being, 'If there's doubt, there's no doubt.'

Bonus? Fuel priced always seem to increase, so we'd be making savings by doing this!

Additionally, we ensured the O rings were good on the filler caps.

Last point is that your engine(s) return more fuel than is consumed, thereby keeping your diesel naturally polished.

Winners all round.

 

[psneeld]

Having biological growth clog fuel separators does NOT signal a big condensation problem.

There is almost always a bit of water in fuel and enough to support growth with little to no condensation.

Pretty tough to tell whether it is occurring in YOUR tanks during any given period of time. Anecdotally, the statement of the vast majority of boaters who leave their tanks at all levels of fuel who don't seem to wind up with water problems points to the "urban myth" conclusion. A few examples of people claiming to have "condensation" or "gunk" problems doesn't make it so.

Not saying that condensation doesn't happen, it just isn't one of the items that one doesn't have to worry about normally (TF gives new boaters plenty anyhow). If I laid a boat up on land for a long period of time in certain climes, I would do either.... fill the tanks or leave them nearly empty and rig some way to drain any water accumulation. While in use in the water, too many factors that affect land based condensation are altered in many boats for me to worry about keeping tanks topped.

About engines polishing fuel.... it does NOT apply to Ford 120 Lehman owners.... they return very little to the tanks...at idle they barley return a drop or couple a minute. There may be other engines similar, so disregard a blanket statement about fuel retun unless to confirm yourself or a very experienced source for your particular engine model.

 

[greatpapabear]

I should have added that we always fully treat the tanks with an anti-diesel bug treatment at the beginning and end of a season, as well as when we refuel.

The key treatment for Play d'eau has been Grotomar 82.