Flushing fuel tank and lines...whew

[heath18703]

Hi everybody I've had a bad time this summer (in the ol '90 Hunter 27 w/ Yanmar 9hp diesel) with my engine cutting out due to water and sediment in the tank. So I've just siphoned everything out of the tank and am about to back flush the lines in an effort to put all this behind me.

Couple questions...

There are 2 lines that come out of the top of the fuel tank that lead toward the engine. One goes through the fuel filter/ separator (under the rear birth) and the other bypasses it and goes straight to the port side of the engine. It routes to the side of the engine next to the bathroom wall and I can't see where it goes to. What is this second line for and how necessary is it that I get to it to be able to back flush it into the fuel tank?

And second...the label on my fuel separator/filter is broken and missing information. Anybody know based on the pictures what sort of filter I need to order? Tag that came off the filter says Model 110.

 

[py26129]

The fuel line that is connected to the fuel filter is the supply line going to the engine, the second is the fuel return line where excess fuel is returned to the tank.

I would not flush / clean anything other than the fuel tank as the filter will get any crud that's in the line between the tank and the filter and anything past the filter is clean.

Then again, depending on the age of the fuel lines, this may be a good time to replace them, as the hoses are fairly cheap.

 

[Ralph Johnstone]

(in the ol '90 Hunter 27

I'll second PY26129's suggestion and replace the fuel lines at 27 yrs old. The lines are relatively inexpensive and it can't hurt.

Here's the filter you currently have .................

 

[Ilanortho]

I had the marine technicians install a servicing port in my fuel tank so it could be actually opened to clean out the tank after 30 years of service.Also installed a primary Racor centrifugal filter in the line before the fuel hits the engine's small fuel filter. Also put a vacuum gauge on the Racor that Racor sells which lets me know if it gets plugged. The latter may have been overkill as our season is short and I service the Racor each winter. Is nice however if I get a bad load of fuel and I don't want to do the human pretzel thing out on the open water to open up the Racor to find the problem if the engine bugs out.

 

[Meriachee]

The short season is more of a problem as the fuel sits for extended periods. We spend more on stabilizer in a normal year than fuel.

 

[Ron20324]

Can anyone suggest a vacuum gauge that is reliable? Heath, Do you need a whole new FILTER, or just the inside filter ELEMENT? I'm about to remove my 110 to upgrade.

 

[Rich Stidger]

Can anyone suggest a vacuum gauge that is reliable? Heath, Do you need a whole new FILTER, or just the inside filter ELEMENT? I'm about to remove my 110 to upgrade.

Ron-
When you upgrade to a new filter, pay attention to the ready availability of replacement elements. Some of the Racor elements are much more available than others. For instance I chose the Raycor 215R filter and learned later that the R15S, R15P, and R15T are NOT commonly available. The 110 filter with its metal bowl means you can't see water and crud in the bottom of the filter. I changed mine out during my first year of ownership.
As for a vacuum gauge, I bought one from Designated Engineer: http://designatedengineer.com/DragPointerLookDown.html

 

[JRacer]

There is some good information from Maine under the Fuel... heading here: https://sbo.sailboatowners.com/faqs/faq.php

 

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[heath18703]

Hey thanks for all the advice everybody.
I think we're just replacing the filter element inside the housing.

Considering all the dark sediment crud that came with the last gallon of diesel that came out of the tank our plan for phase II of the cleanup is to angle a pump up bug sprayer nozzle 90 deg and spray the sides of the tank down a few times with more diesel, then suck it out. Hopefully that'll get everything out of there.

 

[heath18703]

Just had someone suggest I use a more effective solvent other than diesel to wash and dissolve the residue in the tank. Not sure what a good solvent would be though. Any suggestions?

 

[Allan12210]

I used lamp oil. It worked very well for me and is so close to diesel there won't be an issue with some more volatile solvents like acetone, MEK, or heaven forbid, gasoline.

 

[Maine Sail]

Hey thanks for all the advice everybody.
I think we're just replacing the filter element inside the housing.

Considering all the dark sediment crud that came with the last gallon of diesel that came out of the tank our plan for phase II of the cleanup is to angle a pump up bug sprayer nozzle 90 deg and spray the sides of the tank down a few times with more diesel, then suck it out. Hopefully that'll get everything out of there.

If you don't get in there and physically scrub the tank clean, eg: via a clean out port, (Sea Built etc.) the tank will get dirty again, and it will happen more rapidly than the first time around.

Also figure out what size o-rings your deck fill takes (OD and thickness) and replace them with regularity. I order them from McMaster-Carr and change them about 2-3 times per year or more. Bad o-rings are the number one cause of water in fuel and once water is in there the growth of crud only gets worse. If salt water gets in you can quickly destroy the tank.

Best to replace all fuel lines while you are at it. To be EPA complaint, and USCG compliant, the hose for a below deck diesel installation should be USCG A1-15 rated.

Also with a dirty tank you'll want a 10 micron or larger primary filter element with a 30 micron plugging a lot slower than a 10...

 

[heath18703]

Thank you for all that perspective Maine Sail.

Looks like it'll be relatively easy to drain and fill the 2 vinyl fuel lines and inline filter that lead up to the engine. But after that I'm a little unsure what we still need to do to address the solid fuel lines that make their way around the engine. If we get the fuel replaced in the tank, vinyl lines and engine fuel filter, is it still necessary to take the solid fuel lines off the engine to drain, or can we expect the dirty fuel still in them to be pushed through the engine relatively quickly?

And then on air purging.
I believe there's a purge screw on top of the engine fuel filter, closest screw to the mount. And then after that are there any more air bleed screws?