Racor 500 series fuel filter and fuel level therein

[wsmurdoch]

Originally Posted by Laser fun

...it has come up that we are adding 1-2 oz of fuel to the Racor after every 30' engine run to bring the fuel level in the filer housing up to the top of the plastic top of the filter. (About 1/8th inch below rim of Racor housing)

Some are saying this can be normal and some are saying not! Any input appreciated.

Take a look at http://www.hastingsfilter.com/Literature/TSB/94-6R2.pdf

Especially the second page.

"With the fuel system completely sealed and assumed leak proof, then one may ask, how is the air [in the filter] generated and where does it come from? The source of air vapor is in the diesel fuel itself. Similar to water, diesel fuel contains a certain amount of dissolved air, depending upon the fuel temperature, pressure on the fuel, specific gravity and the amount of aeration to which the fuel has been subjected."

If your fuel filter is under partial vacuum, some of the dissolved air in the fuel bubbles out and accumulates in the top of the filter. It does no harm and is normal.

[motaman9]

Originally Posted by Laser fun

Hello. First time poster and long time reader. After water contamination problem on ICW we're back in the slip. We've been running the Yanmar 3gm30f daily to ensure water out of system.

Now it has come up that we are adding 1-2 oz of fuel to the Racor after every 30' engine run to bring the fuel level in the filer housing up to the top of the plastic top of the filter. (About 1/8th inch below rim of Racor housing)

Some are saying this can be normal and some are saying not! Any input appreciated.

Original reason for all the engine test runs was to remove water and air from the fuel line we replaced. Most if not all replaced clamps on the fuel line has been checked and tightened ... Again. The fuel tank pressure relief value has been checked and is free and clear to make sure there was't a vaccum.

Thanks.


Sent from my iPad using Cruisers Sailing Forum

We are currently evicting some gremlins from our fuel system and recently reviewed a LOT of Racor maintenance videos and manuals. If I am reading your question correctly the fuel level in the Racor housing is only 1/8" below the rim of the filter compartment ? I can't see why that would cause a problem. As I understand it from watching the Racor filter replacement videos, you can even run a filter half full (not a great idea or efficient use of the filter since you'd only be using the bottom half of the filter element and it would clog faster) and it should operate normally. After all, if the fuel is only down 1/8" it is still even with the filter "frame" and not even down to the paper element yet, right ? Or am I missing something ?

Good luck....


www.learntoliveaboard.com

[Terra Nova]

Originally Posted by Laser fun

...Prior to the engine run all the clamps were checked for tightness...

Not adequate to insure no air leak.

[jongleur]

Originally Posted by Rustic Charm

The filter 'filters' dirt and grime. That's its purpose. To 'filter'.

Not to belabor the point, but my
understanding is that lift pumps are
commonly vane pumps that will be
little bothered by dirty fuel.

Also, I have mostly used tanks
above the filters and engine, which
makes this whole thread unnecessary.

[antoha]

Bill, as people say back home: it's better to be rich and healthy than sick and poor. sure, if you had perfect design and infinite resources to maintain everything, nothing would be needed, but if people are asking this question - their design isn't, right?

for example, my boat is "a classic" (from the 60s). it was common to place the tank in the keel in those days, and my fuel tank is well under the cabin sole. changing this is costly both in terms of the amount of labor and money involved, so one wouldn't without dire need. so let's assume it's not an option; tank is below the engine, and you need a lift pump.

let's also assume lift pumps can deal with dirty fuel (which is partially true; but my lift pump once literally blew up [was all black after it tripped the engine fuse], and i suspect that a piece of metal from a racor fitting [on the output of the racor] corroded and fell off and made it into the pump). suppose the racor element which you placed after the lift pump clogged up, and to make the example more clear - clogged up really well. your pump keeps pumping, but nothing is coming out (flow very restricted). what pressure do you test the clamps to? aren't you afraid the pump will create enough pressure for a connection between the pump and the racor to come lose and start spitting fuel all over the place? and you can clog up a fuel filter pretty quickly if your sludge which had always been on the bottom and you hit some chop which set it loose - even more so if your tank is big enough to have baffles and a nice chunk of goo worked itself free from a corner somewhere.

i understand the standard answer to this would be "always clean your filters and never let this happen", but creating such a weak link in the system is not too wise, in my opinion. btw, as per ABYC requirements, if your tank is not below your engine, you must have a shutoff right at the tank pickup, so you don't end up syphoning the contents of your tank out in case you get a break in the line, so tank below the engine is more fool-proof/robust.

[jongleur]

...my fuel tank is well under the cabin sole. changing this is costly both in terms of the amount of labor and money involved,...

My main tanks were in the bilge also,
so I had a day tank made that held 9
gallons, that was 18 hours of motoring
at 1/2 gal/hour. Didn't cost much,
saved a heck of a lot of work, never
having to bleed the system/engine.
Could only lose that amount if something
siphoned/backed up. Should be easy to find
space for that big a day tank.

...what pressure do you test the clamps to?

It's my understanding that a vane
pump can continue to spin with
complete blockage with no increase
in pressure.

My day tank always had clean fuel in it.
I tapped it off the V shaped bottom.

...tank below the engine is more fool-proof/robust.

I beg to differ. More than one way to
skin a rabbit.

[jongleur]

Oh, but I like to think that I'm smarter
than I am rich.

...and I am rich...

[Terra Nova]

Originally Posted by jongleur

...my
understanding is that lift pumps are
commonly vane pumps...

The term "lift pump" generally refers to the mechanical pump provided on the engine to pressurize the fuel system. These are commonly diaphragm pumps.

[jongleur]

Originally Posted by Terra Nova

The term "lift pump" generally refers to the mechanical pump provided on the engine to pressurize the fuel system. These are commonly diaphragm pumps.

It's my understanding that we are
discussing a pump even before what
you have called the lift pump. What
would you call this pump if the pump
on the engine is the lift pump?

[Terra Nova]

The pump that transfers fuel from main tank to day tank can be called a transfer pump.

[jongleur]

Okay. My "transfer" pump was a
hand pump. Every 18 hours or so
I pumped a few times and filled
my day tank which then gravity
fed my engine through my parallel
plumbed Racor filters which were
individually valved so if one had a
problem, they could immediately and
easily be switched. Worked well
for many many years.

Rendered all the doom and gloom
in this thread moot.

[svHyLyte]

Originally Posted by svHyLyte

On our yacht, as on our previous yacht; and, as on most of the yachts I have been acquainted with, the lift pump was before the fuel filter(s). Further, on our yacht, as on our previous yacht, the top of the fuel tank is well above the top of the fuel filter in which case, with adequate fuel in the tank, one doesn't need the lift pump at all to fill the fuel filter canister, which fills via gravity once the locking screw is released slightly. This arrangement, coupled with the check-valve in the FG500, prevents one getting air in one's fuel feed line and, consequently, needing to "bleed" ones engine, something I have not had to do for upwards of 10 years.

FWIW...

Oop's! My foregoing comment/use of terminology was in error. On our boat (and previous boat) we have what is properly known as a "purge pump" before the primary (Racor 2mc) filter and a mechanical "lift pump" (engine cam driven) between the primary filter and the engine mounted Perkins filter.. While the subject/discussion has not been active for awhile, I felt I needed to correct the record once I realized my error.

FWIW...