Fuel Filters in Series

[SimonV]

Because I have had problems in the past, I now make sure I have one full 20lt jerry can that I can put on line in about 5 min this gives me about 10hrs of motoring. After having a fuel bug problem where the tank pick up became blocked causing a vacume stopping the engine . What I did was crack the filter lid, I sailed into the harbour and when near the fuel dock at the marina started the engine which lasted long enough to tie up. I organized to have the fuel polished but the marina would not allow this at the fuel dock and they wanted $250 to tow me the 50M to a nearby berth. So with 6 feet of spare water hose I put one end in the jerry can and conected it to the fuel line using gravity to feed the engine. I had to bleed the engine and it ran like a champ. from the time I had the engine running and the trip to the berth would have been 10 min max and this took half the fuel out of the jerry can. I now have a fuel hose set up so I can run fron a jerry can if ever needed, with a return line going back to the jerry can.

[Irish rambler]

Hiya Simon V, Yep, I agree but if I may respectfully make a suggestion, why don't you cure the cause of the problem, remove and clean your fuel tank ? 'Fuel bug' is caused by growth of microbes at the interface of water and fuel. Take out your fuel tank, fit a sump and water drain.
Open the drain cock and drain off any water and fine sediment 24 hrs after you fill with fuel, end of problems. Fix the reason for the problem not the effects of it.

[SimonV]

s

Originally Posted by Irish rambler

Hiya Simon V, Yep, I agree but if I may respectfully make a suggestion, why don't you cure the cause of the problem, remove and clean your fuel tank ? 'Fuel bug' is caused by growth of microbes at the interface of water and fuel. Take out your fuel tank, fit a sump and water drain.
Open the drain cock and drain off any water and fine sediment 24 hrs after you fill with fuel, end of problems. Fix the reason for the problem not the effects of it.

Thats what I did last week. The problem was they built the floor on top of the tank I had to cut a panel 3x2 feet then two 10 inch holes in the tank.
This still only allowed me to get to the centre and port side of the tank so I had to do the best with a gargen pressure spray to try and reach the other parts. the bottom of the tank looked like someone had been keeping rabbits, little balls of fuel bug which when damp wer quite firm but turned to dust when dry. 30+ years of bug, dirt and varnish cleaned the best i could then shock treated with Fuel Doctor it 1 to 100. I hope all will be well from now on.

[Uncle Bob]

Originally Posted by SimonV

s

Thats what I did last week. The problem was they built the floor on top of the tank I had to cut a panel 3x2 feet then two 10 inch holes in the tank.
This still only allowed me to get to the centre and port side of the tank so I had to do the best with a gargen pressure spray to try and reach the other parts. the bottom of the tank looked like someone had been keeping rabbits, little balls of fuel bug which when damp wer quite firm but turned to dust when dry. 30+ years of bug, dirt and varnish cleaned the best i could then shock treated with Fuel Doctor it 1 to 100. I hope all will be well from now on.

Had the same problem but tanks are integrated glass- impossible to remove- but the po had installed filler fittings to the top of tanks above the deepest section.
I bought a fuel transfer pump 50 l / min and a water seperator/filter which I installed on the suction side of the pump, a long wand to reach the bottom of the tank, the fuel return to the deck filler and could not believe the crap that came out of the tanks.
I simply run this in each tank for fifteen mins and no more bug (touch wood). I plan to do this each 6 months.
I also now use fuel doctor addative.

[Dantodd]

Even of you don't have room for parallel filters couldn't you put a bypass at each filter and ohave one bypassed to act like a parallel filter. If one clogs flip over to the other. There could well be some dirty fuel in the line between the filters but if you typically run with the filter closest to the engine in bypass the only time the dirty fuel would come into play would be after you've already fouled two filters and try to switch back to the initial filter. Even then if you are getting any draw through the engine side filter you should be able to run in series for a short while to clear out the intermediate line.

[Irish rambler]

SimonV, assuming you are on a sailboat, here's a handy way. buy a cheap 12 volt submersible water(yep, it will do the job) pump from a camper/rv shop with a 3/8'' outlet, get as much 3/8'' hose as you need and enough spare cans to hold the fuel in the tank. get access into the tank on the port or stbd side, reduce the level to between 1/4 and empty. Then rock the boat repeatedly to agitate all the crap and get it in suspension within the tank, then careen the boat over, tie a rope to the mast and pull it over, or fill drums with water to tilt it over, so that the access port into the tank is on the lowest side, pump all out, put in 5 gall of paraffin to flush, repeat rocking/cleaning until the tank is clean, Filter all new fuel into the tank through a double thickness of a pair of ladies tights. That will cure your problem and save an expensive fuel polishing bill. Then go to the pub and blow the froth of a tinny or two.

[Irish rambler]

Dockhead, I ran my Perkins 4236 across the Irish sea and round lands end to Falmouth on a blend of LIDL rapeseed cooking oil (they had an offer on at the time) it was cheaper than green/red diesel, blended with 25% paraffin. All diesel engines will run perfectly well on Bio diesel, the reason there are problems is because people don't drain off any condensation in the boat tanks sump, if there's any water present the diesel bug will become rampant at the fuel/water interface. The second 'problem' is that bio fuels are self cleaning and any crud in your tanks will be scoured, off course this will necessitate several filter changes until the system is clean. The trick of couse is to keep your fuel tanks clean and free of water, as I said in an earlier post a 12v 3/8 immersion water pump from a camping/rv shop will lift any water from the base of the tank into a plastic container no problem.

[zeehag]

had a large problem with multiple filters in line--- that let air into system and nonfunction of engine in time if need. i quit my series filtration and left only the filter on my engine and the racor. i hope that cured the problem......we will see in am when i again try to make my boat motor into an anchorage from a very incredibly pricey marina.....

[leftbrainstuff]

Good advice from many posters so I'll reiterate some rules of thumb:
1) Pumps are better at pushing than sucking. Minimising any pressure drops on the suction side will put less stress on the pump and help to avoid cavitation which is to be avoided at all costs. Cavitation introduces 'air' and can cause erosion.
2) Redundancy in filters is good practice. Plumb in parallel.
3) Size filters to the flow. Too small will increase pressure and hurt flow. Too big and the filter is woeking unevenly and can trap air
4) Have air bleed points at all high points of the plumbing
5) use strainers sized to protect the pump on the inlet side and use filtration to protect the next component in line
6) Monitor differential pressure aceoss your filters and you'll have a visual indicator of pending flow problems

[Irish rambler]

Zeehag,
Sometimes systems can simply become too complicated by the wrong initial approach to the problem and it's totally unecessary, K.I.S.S, clean your fuel tank first..... Tie your boat securely alonside,fore and aft with springs, try your engine in gear under light load to find your air/fuelproblem, be methodical to find the fault, fixing it's easy.
A polite note of caution, choose a time when you won't annoy your neighbours with engine noise or wash from your prop. A wee tip, if you spill a tiny drop of fuel overboard and get a rainbow effect, a good squirt washing up liquid will break it up.

[zeehag]

Originally Posted by Irish rambler

Zeehag,
Sometimes systems can simply become too complicated by the wrong initial approach to the problem and it's totally unecessary, K.I.S.S, clean your fuel tank first..... Tie your boat securely alonside,fore and aft with springs, try your engine in gear under light load to find your air/fuelproblem, be methodical to find the fault, fixing it's easy.
A polite note of caution, choose a time when you won't annoy your neighbours with engine noise or wash from your prop. A wee tip, if you spill a tiny drop of fuel overboard and get a rainbow effect, a good squirt washing up liquid will break it up.

we polished fuel twice--is clean, like squeaky clean, and only air introduction, aside from the newly discovered disintigrating pressure hoses for oil system, with remote filter not able to be placed on engine directly---- is probably to be relocated to an anchorage tomorrow, i pray.....ancillary non functional fuel filter, air introducer has been removed and so have the bad lines for oil.. we be jammin soon....

[skipgundlach]

I'm coming late to the party, but I think an original question had to do with fuel filters in line...

Aside from the increased pressure to move fuel when you put two identical filters in series, it's actually more inefficient than you'd think, as well.

That's because the more a filter is used, the smaller its pass-through size gets. Thus, if you start with 30 micron, and run it for a long time, it will be allowing 30 micron initially, but may drop past 20 micron passage due to the clogging of the larger holes.

So, if you had a second 30 micron behind it, it would likely get nothing on it after the first initial burst, because being a new filter, with fuel of less than 30 micron contaminant, all would pass through that filter unobstructed.

It's for that reason that my fuel polisher (very simple, not very expensive) has a 30 micron followed by a 10 micron filter. The big stuff gets caught by the 30, but, as it clogs up, it gets smaller and smaller. I (in the few times after my wreck that I've had to change it) have found that the second filter is usually VERY much cleaner than the primary, despite it being a third of the passage rate.

Belt and suspenders, I also have parallel dual 10 micron Racors. The efficacy of my fuel polishing setup is such that I had my first Racor change (throw two valves and it's done) over 1000 hours after its first use. At that, it wasn't actually clogged (though it was very black); I had a small air leak that I tracked down after changing the filter as the expected reason for the failure to continue running.

FWIW, any time the boat is under power, I run the fuel polisher. And, unless there is some concern for current battery state, whenever we're in a rock-and-roll (typically downwind, or big seas of any time) conditions, when we are under sail.

We have a slight advantage over most 34-year old boats in that we had a wreck wherein Flying Pig had 8-10' seas for an estimated (based on the duration of the storm) 3-5000 impacts on a flat shelf that's normally dry at low water. With a half-filled tank, I'm sure that ANY junk on the tank surfaces were dislodged. We ran the polisher during the entire salvage tow home, changed the filter when we were out of the water (EXTREMELY gungy - but the Racors were fine), and ran it all the time we wallowed under staysail alone (the remaining sail) from Marathon to St. Petersburg, changing the filter again once we were in the yard again. That change wasn't nearly as bad as the prior one, but was still pretty dirty.

However, that got the most of it, as the last change we did had no actual sediment or gunge, other than directly on the filters.

My fuel polisher cost well under $500, and doesn't take up all that much room. It uses the same intake and return lines as the engine. Highly recommended project for anyone who voyages. Start with a pristine tank, and keep it that way; your Racor changes will disappear :{))

L8R

Skip

[skipgundlach]

Originally Posted by zeehag

had a large problem with multiple filters in line--- that let air into system and nonfunction of engine in time if need. i quit my series filtration and left only the filter on my engine and the racor. i hope that cured the problem......we will see in am when i again try to make my boat motor into an anchorage from a very incredibly pricey marina.....

My diatribe on filtration didn't include what I did to isolate where MY problem was when the engine stopped, and then wouldn't keep running :{))

I thought I had checked literally everything, but a new filter, manual prime, bleed, start, and die repeatedly other than the filter happened again and again.

I'd been checking my connections from the tank side. I finally went from the engine side, and put a wrench on each one. I'd forgotten the one at the manual lift pump. Once that was tight, the problem was cured...

Hope you got out and that things are again as you'd like them!

L8R

Skip

[Irish rambler]

Seems to me my 'cousins' on the other side of the pond are getting an awful lot of dirty fuel delivered on their travels..
Rip the tights off your girlfriend/wife or significant 'other half' !
Place one leg inside the other, place the pistol grip of the delivery hose inside the thigh section of the tights, place the 'leg' of the tights in your filler hose, fill very slowly,use two pairs of tights for a finer filter. that will filter out any crud going into your tank in the first place but remember fuel is like fine wine it has sediment in suspension, the fresher it is the more sediment will be in it, so you still need to clean your tank regularly(every couple of years) depending on the area you live in