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Dave_E 08-11-2014 11:01 AM

Clogged fuel filter woes - advice
Hi All,

One month after changing 2 fuel filters (1 spin on at the motor and 1 Racor), filling the tank up, going on an 8 day cruise + one outing since then...

Yesterday we were going out and 5 minutes out of the slip the engine died. Put out the foresail and limped back to a guest dock, where I did some quick looking. I did not run out of fuel, turned on the key (electric pump operates) and had fuel at all the bleeders. Clogged filters? So I went and bought a couple, installed, bled... engine runs like a top.

I have a 30+ year old 40 gal aluminum tank, the boat sat for 2 years and I have been using it for 1 year. With so many mixed opinions about fuel polishing, tank cleaning etc. I think I could accomplish the same thing by changing fuel filters. It's easy, I got the hang of the bleeding thing. But I don't like the surprises like yesterday.

What kind of indicators (electrical or manual) for fuel restrictions are there for marine 24hp engines? What are some of your thoughts on the subject?

Thanks - Dave

copacabana 08-11-2014 11:30 AM

Re: Clogged fuel filter woes - advice
Dave, thankfully there is a simple solution for this- clean your tank and fill it with fresh diesel. If there's an inspection port on the tank (and there should be) it's a simple matter of opening it up and removing the old diesel. Then wipe it out with rags soaked in kerosene, taking care not to leave any bits of rag in the tank. Fill it up with new diesel and you're ready to go! You might consider adding a biocide after the cleaning to prevent further fouling of the tank.

Multihullgirl 08-11-2014 01:05 PM

Re: Clogged fuel filter woes - advice
What copacabana said. A 30YO tank is going to be lined with goo clinging to the walls, if my 20YO tanks were any indication. I had to cut ports into mine to get to it, but it was worth all the effort. BTW, based on what I found, I don't have any faith in "fuel polishing." I can't imagine this crap coming off without manual effort.

The crap in there is fairly stable until you get into some rough water, and then a little gets stirred off the sides and bottom, clogs the filters probably when you need the engines to run. But not all of it comes off, so it never ends. Just take the medicine and clean the tanks.

dabnis 08-11-2014 04:02 PM

Re: Clogged fuel filter woes - advice
I have seen pictures of fuel pumps that have a fine screen built in, may be worth checking?

Paul T

T37Chef 08-11-2014 04:31 PM

Re: Clogged fuel filter woes - advice
I never had fuel problems but I did have my tanks cleaned by a professional after the boat sat for two years, and before running the newly installed engine...very glad I did as the algae growth was significant. I don't have an inspection port so they went through the fuel pick up tube, screen wasn't horrible but did need cleaning. They shocked the tanks then came back two later, removed most of the fuel (yes that hurt, 50 gallons, but it was time), cleaned it with a high pressure wand then removed the remaining fuel and any deposit on the bottom.

I installed a fuel polisher by Racor that is also a back up filter when I set the valves (total of three). Remember your engine returns some fuel to the tank when its running so that in itself is a "polisher" so to speak.

That said, your injection pump of injector could be clogged? or malfunctioning. If changing the filters this many times hasn't solved the running of the engine, I doubt continuing to do so will fix it.

What micron primary do you have, maybe that getting clogged, perhaps a different size would help...

Hard to say, going to be somewhat trial and error I think...but I'm no mechanic just a over the shoulder wanna be :)

Group9 08-11-2014 05:50 PM

Re: Clogged fuel filter woes - advice
The other option is just keep changing filters. When I bought my boat, it had been sitting up for about a year without being sailed. Once I got going on my cruise in it, and shaking things up, I was changing out fuel filters every week or so. It was annoying but, after a few weeks and lots of fill ups, I guess I got the gunk out and fuel filter changes resumed to more normal schedule. :)

RichH 08-11-2014 07:39 PM

Re: Clogged fuel filter woes - advice
There are several 'indicators' used for a well designed and maintained boat fuel system:

1. Calendar --- scrub out the insides of the tank about every two years regardless of fuel quality.

2. Vacuum gages on all fuel filters. Here's how to set up for YOUR system:
a. Clean the tank, put in NEW fuel and NEW filters
b. Run the engine at near/below wide open throttle - WOT, read and record what you see on the gages ---- this is the 'benchmark' pressure/vacuum for a new/clean system, you'll probably see 'nil' vacuum on the gages.
c. Have an assistant standby on the tank valve, engine running below WOT; at your signal the assistant slowly closes the tank valve while you monitor the 10然 filter's vacuum.
d. RECORD that vacuum value where the engine starts to 'stumble' due to fuel restriction - This is your fuel system MAXIMUM vacuum value read at 'any' filter.
e. Multiply that max. value by 0.80 --- this is your new 'its time to change the damn filters value'. When a filter has consumed 80%+ of its 'dirt capacity', the time to full shutdown is exponentially quick ...... meaning with respect to gallons or time remaining, you probably only have 5-10% reserve capacity remaining in the filter before clogging.
d. option - usually the 10然 filter is the one to clog first, even if preceded by a 30然 which is installed to extend the in-service life of the 10然. Get a fuel oil compatible 12vdc operated vacuum/pressure switch with adjustable 'set point', wired to an alarm. Adjust the 'set point' on the press/vac. switch so that the switch closes and turns on your alarm at the 80% value of where your engine begins to 'stumble' at near WOT.

tank --> 30然 --> 10然 --> 15-17然 small engine 'guard' filter ---> engine.

Note: if youre plugging filters and you cant get inside and clean the tank ... ADD a 30然 filter to extend the service life of the 10然. If that's not enough in-service time increase, then add another 30然 in parallel to the first 30然 and run them BOTH at the same time. Nutherwords, if your system is always plugging, increase the SURFACE AREA of your filters and your prefilters.
If youre plugging even occasionally, ultimately you will have to get inside and clean the tank.

erps 08-11-2014 09:39 PM

Re: Clogged fuel filter woes - advice
I learned the lesson about keeping your tanks full during the winter the hard way this spring. Nikko carries 100 gallons of diesel in two tanks. We ran one tank down to where we believed it had about 10 gallons left inside then switched over to the other tank for the rest of the winter. In May, we got to a point where the tank we had been running on was getting close to empty by our reckoning, so on our way home from an outing, we switched to the other tank that had been mostly empty all winter. Then the motor died. Pulled the cover to the Racor, saw it was full of water and drained it and then ran a hand pump to prime it and just got more water. We eventually made it home.

Later, I pumped out both tanks. I eventually got five gallons of water out of that lower tank after all the five gallon buckets settled out at home in the garage. I was pretty impressed at how much water had accumulated. Working through the 1.5" fitting for the fuel hose, I was able to swish some hot soapy water around the bottom of the tanks with a long stick then used a small diameter shop vac hose to suck it back out. Tanks aren't absolutely clean, but they're good enough to last another thirty years.

deniseO30 08-11-2014 09:50 PM

Re: Clogged fuel filter woes - advice
if at all possible replace the tank.. even with a smaller one that is easy to remove. Used a 19 gallon plastic moeller to replace the 26 gal tank I had in my old boat. warning, (seepage) pin holes are highly likely to magically appear after cleaning!
Also don't forget to clean the pick up tube that draws the fuel from the tank.. How do I know?

Group9 08-12-2014 08:38 AM

Re: Clogged fuel filter woes - advice

Originally Posted by deniseO30 (Post 2089513)
Also don't forget to clean the pick up tube that draws the fuel from the tank.. How do I know?

I had a stoppage coming into Nassau Harbor, and had to sail in. When I finally took everything apart, I had what looked like a piece of seaweed (about an inch long) that had got caught in a 90 degree elbow in the fuel line between the tank and the Racor filter. Amazing what can grow in diesel. :D

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