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Alex W 04-18-2013 03:22 PM

Clogged fuel filter?
Last night my engine quit as I was sailing back towards my marina. More details:

Winds were about 20 knots and there were 2-3 foot wind waves due to a moderate (1-1.5kt) current. It was getting dark and we needed to get back faster than we could by tacking, so we decided to motor.

When I first turned on the engine (Yanmar 2GM20F) I noticed that it didn't seem to want to rev as high as normal. About 10 minutes later after crashing through the waves the engine speed dropped to under 1000rpm. I thought that a crew member had knocked the throttle, but that wasn't the case.

When this happened I turned off the engine and sailed to the inside of our breakwater. After that we limped the long way through the marina at just over idle speed to avoid having more problems.

My guess is that this is due a clogged fuel filter. The waves probably churned up something nasty in my fuel tank and it clogged the Racor primary filter.

* How do I verify this? Is replacing my fuel filter and running at a high RPM in neutral (what a waste of fuel) an acceptable test? I'd prefer to test it at the dock rather than having to dock under sail.
* Is there a good way for me to run all of the fuel in the tank through a filter to "polish" it? I know that I can pay for this service, but I'm wondering if there is a DIY approach.
* My Racor filter is ~25 years old and doesn't appear to be supported anymore (it is the old model with a band clamp). What is the appropriate Racor filter system to buy for a 2GM20F? A Racor 120A?
* Are there any warnings of a clogged fuel filter before it happens?

Sabreman 04-18-2013 05:10 PM

Clogged fuel filter?
You have a classic case of fuel starvation. Most likely you don't have to polish the fuel unless its more than a year old. A common cause is not necessarily a clogged filter which is easy enough to check. Rather, there may be a screen at the bottom of the fuel pickup in the tank. When you tossed around in the chop, you stirred up gunk and it may have clogged the screen. When things settled, the junk fell away and the engine started.

Remove the screen and let the Raycor catch the junk. Use a biocide in your fuel. Get a new Raycor that accepts a 2010 Raycor filter, because the filters are ubiquitous.

You may need to empty and clean your tank if it hasn't been done. Polishing won't do this.

Both our Sabres and my sister's Cape Dory had this problem. We cleaned tanks and removed the pickup screens. Never a problem since. If you have no screen, then you probably have a tank full of crud that needs to be emptied and cleaned.

If course, all this presumes that your filters are clean to begin with.

Faster 04-18-2013 05:17 PM

Re: Clogged fuel filter?
Sounds like you had the warning.... the reduced rpm was it.

A totally plugged filter would prevent you running at all, but for a smallish engine you may get idle demand fuel through it.. Your symptoms sound also like possible air entrainment.. check all your bleeders and vents in case something's vibrated loose - fittings/connections too.

Change the filter, obviously, fully bleed the system and you should be able to 'test' it at the dock - tie the boat up securely and try it in gear too..

I have 'polished' our fuel - we had some sediment in the tank, I removed it all with a suction oil changing pump/cannister, poured it into jerry cans, mucked out the tank as best we could, then ran the fuel between jerry cans (J cloth in a funnel for the first phase) then through various filter screens before screening it once again going back into the tank. Not a true polish job but we've had no issues since.

btw I put all my fuel through a screened funnel to catch the gross stuff before it can go into the tank.

Minnewaska 04-18-2013 05:40 PM

Re: Clogged fuel filter?
Easy to check. Pull the filter and have a look. If they don't make it anymore, I'm guessing you haven't changed it in a while? It is an annual requirement at a minimum.

Another mistake people make is to put too tight a filter as their primary. 20 or 30 microns is fine. Your engine mounted secondary is probably 2 or 5 microns and some use the same on the primary. Not necessary.

The simplest way to clean up your fuel is to drain it all out and put it back through one of those fuel filter funnels. Not exactly polishing, but if it needs more, I personally think you need new fuel.

Once drained, if you have an inspection hatch, I would take a look and see if there is any gunk at the bottom of the tank.

Alex W 04-18-2013 06:12 PM

Re: Clogged fuel filter?
The previous owner told me that the fuel filter was replaced last summer (we bought the boat in the fall). I took his word for it and had "replace fuel filters" on my mind since then, but haven't made it a priority. I didn't look closely at the fuel filter (beyond seeing that it was a Racor) until last night. I didn't know about that screen either, I will check for that.

Thanks for the ideas on how to filter the fuel that is already in the fuel tank. I'll see if I can find some jerry cans to use. There is about 8 gallons of fuel in my tank right now.

I don't think that my fuel tank has an inspection port, but I will double check.

dabnis 04-18-2013 06:24 PM

Re: Clogged fuel filter?
Some fuel pumps may have integral filters in them. If everything else checks out, you might want to pull it for a look. Also, make sure your tank vent is not plugged, you should be able to easily blow through it.

Paul T

Minnewaska 04-18-2013 07:31 PM

Re: Clogged fuel filter?

Originally Posted by Alex W (Post 1018221)
....There is about 8 gallons of fuel in my tank right now....

That's not a lot of fuel. Did it sit all winter without stabilizer or biocide? If so, I would just get rid of it and start fresh. Fuel degrades.

Alex W 04-18-2013 08:48 PM

Re: Clogged fuel filter?
No, it didn't sit all winter. I sail this boat multiple times per week, including through the winter. It has biocide in it.

Sabreman 04-18-2013 10:26 PM

Re: Clogged fuel filter?
On our current boat, I noticed some slightly diminished RPMs, about 100, during the first season. After I pulled the screen from the intake, the engine worked perfectly. When I pulled the filters as part of normal maintenance later in the year, the RACOR was covered in sludge. It's a miracle that any fuel made it to the engine. What happened is that sludge from the tank was sucked to the Raycor and stopped, which is exactly what a filter is for. Since then, the Raycor has been pristine when I change it out.

Let the filters do their job.

PS. I'm not a huge fan of polishing - I prefer to go on a trip and burn the stuff, replacing with fresh. That's much more fun than rigging pumps and hoses and stuff. :)

Faster 04-18-2013 11:31 PM

Re: Clogged fuel filter?

Originally Posted by Sabreman (Post 1018367)
PS. I'm not a huge fan of polishing - I prefer to go on a trip and burn the stuff, replacing with fresh. That's much more fun than rigging pumps and hoses and stuff. :)

With that thought in mind.. depending on the usage of the boat, a large capacity fuel tank may not be a good thing...

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