question about Racor fuel filter... - SailNet Community
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question about Racor fuel filter...

I have the old style Racor fuel filter from decades ago. It is getting a bit tired.

This is the newer style...

https://www.asap-supplies.com/parker...SABEgI6u_D_BwE

I am concerned about one thing though.
The old style gave plenty of warning if there was air in the fuel as there was a fuel "curtain" in the filter and you could see clearly that there was air in there before it risked stopping the engine.

The newer style doesn't appear to have a fuel curtain, no, just that strange multi-ported? central section that does not seem to be able to preclude air.
I must be able to see the presence of air before it stops the motor !

Am I seeing this wrong?

Thanks

Last edited by Rockter; 4 Weeks Ago at 02:13 AM.
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Re: question about Racor fuel filter...

Those ports swirl the fuel in the bowl, prior to being picked back up to go through the filter and to the engine. As I understand it, the centrifugal force pushes heavier water and solids to the outside, which slide to the bottom of the bowl. All I know for sure, is they seem to work, as I've capture both.

Not following the air problem, nor why your system seems to have recurring air in the fuel lines, sufficient to stop the engine.


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Re: question about Racor fuel filter...

My Racor is mounted above the fuel level. There is a primer bulb in the fuel line that I use to fill the Racor with fuel when the filter is replaced. After the filter is filled and the top tightened down, I don't see how air can get in the filter at all.... Where is the air coming from that gets to your filter?
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Re: question about Racor fuel filter...

Guys...

It's not a question of the source of air in the fuel lines, it is a question that if air gets in there I want to see it in the bowl before it stops the motor.

The earlier Racor 200FG (the one I have)...

https://www.usedvictoria.com/classif...rator_33576051

...has a fuel "curtain" and if you have an air ingress you will see the air creeping down the outside of the fuel curtain and you can take action to purge it before the motor stops.
In absence of that fuel curtain, the motor may just stop, leaving me with having to guess why.

The later model, the 500FG, does not seem to have the fuel curtain.

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Re: question about Racor fuel filter...

The smallest Racor fuel filter is rated for about 10-12 gallons per hour flow. Most small sailboat engines consume between 3/4 - 1-1/2 GPH at maximum flow - WIDE OPEN THROTTLE. Most of the 'clattertrap' you see inside Racors is to provide 'dynamic' removal of gases and contaminants from the relative HIGH VELOCITY fuel. 3/4 to 1-1/2 GPH inside a 1/4" tube is virtually 'nothing' velocity; thus, all that filter fancy-ness is of no benefit for such small flow rates of sailboat engines.

You mention occasional air captured in your fuel filter. The causes in order of severity/vulnerability are:
1. developed pin hole in the engine's lift pump - pump sucks air (from the crankcase) on the 'downstroke' (fill-stroke) of the diaphragm
2. You have 'compression fittings' installed somewhere on the 'suction side' of the fuel line .... Compression fittings are notorious 'leakers'. Fittings on fuel lines operating on vacuum should be double flared fittings with metal ring seals internal to the 'fitting'.
3. The observance of air in the filter follows a heavy sea state where the fuel in the tank is mixed into a fuel/air emulsion due to the violent shaking of the boat's fuel .... you need more baffles inside your tank.

For air removal from fuel lines due to unknown causes (until you find the problem), take ANY diesel fuel compatible filter housing (with integral drain) and install it UPSIDE DOWN and after the last filter in the 'filter train'. Any air in the tubing will be captured in the upside down housing. Since the filter, now known as a 'knock out pot' will be trapping air and will be located quite low in altitude in relation to the highest level of inlet tube from the tank .... to remove the air, ... engine off, and the fuel thus able to siphon from the tank to the knock out pot .... open the now inverted drain, the air will burp out though the drain valve when opened. Better is to install a clear 1/4" polypropylene pig tail on the drain port and with a small valve on the terminal end of the pig-tail. You will SEE the presence of air in the pigtail and will know when expel the air from the 'knock out pot'.
Before you go to all that trouble, I would offer the suggestion to carefully assay your entire fuel delivery system to find (in order as previous listed) what is the source of the air LEAK - consider to replace all those *compression fittings* with double flared connection fittint with integral metal ring seals.

Note: Good filter engineering design should include: ......Racor filters should be mounted at the LOWEST altitude of the entire fuel delivery system so that if there is an errant air leak, that air will move by air 'buoyancy' to the highest level of the fuel delivery system .... usually to the engine mounted 'engine guard' filter or back to the tank. The same principle will apply for errant water in the fuel system - wth the Racors at the lowest level of the system, drain the racors to remove the water. If you use 'cartridge type' Racors, consider to install an empty filter with drain as a water knock-out pot.

Last edited by RichH; 4 Weeks Ago at 10:53 AM.
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Re: question about Racor fuel filter...

Quote:
Originally Posted by Rockter View Post
Guys...

It's not a question of the source of air in the fuel lines......
Of course, it is. Even when a Racor separates water, the first thing you want to know is how the water got in there. It might be an errant fuel fill, but it could also be a recurring poor o-ring on the filler cap.

Hope you figure it out.


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Re: question about Racor fuel filter...

I would also confirm the operation of an anti-Siphon valve if fitted, typically used when Filter is below fuel level. Usually you hear it "Rattle" when priming after a filter change, and can be a first source of restriction in a system. I also recommend replacing ALL fuel hoses unless you know how old they are. Worst case they will feel hard and will start breaking on the inside, a sure clue is small black particles in any of your filters. I had a shut down one time (first day out) when Boat was new to me, the air vent on top of the filter worked loose and was pulling air in.
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Re: question about Racor fuel filter...

Minn :
I need to know if the Racor filter FG500 will warn me of air ingress before the engine stops, if it ever stops.
That's all.
I suspect it does, indeed I suspect it must.
There is an air leak somewhere, I know, but without the air-in-fuel warning of the filter fuel "curtain", it could be other reasons why it stops (and it hasn't stopped for decades), but it would be good to see air ingress before it stops the motor, if it ever stops again.
I will give Racor a call. I trust they will know.

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