Flushing Fuel Tank

[Richhh]

You have to be damn careful when using inert gases inside a boat ... the inerts can easily displace your breathing air ... and kill you just as fast as an explosion. I prefer to fill the tank with water, then do the cutting ... as I can see water.

Hey Alan, the 2 poor men killed welding, was it a diesel tanker? Everything has to be weighted as to importance. If I were training welders I would give the same advise as you. I did it because it was my boat and the alternative was unacceptable. Working on old steel boats requires a sense of adventure and fast thinking some times. If you can do something to mitigate the risk you do it but no matter what, the job has to get done. The job I mentioned above came about because the idiots that owned the boat before me used a bilge pump locker as a wet locker. The tank below was wet much of the time for 25 years. As I was finishing the tank repair I saw an area of rust scale on the hull plate next to the top of the tank, (non-intergal tanks) a spot where the painter missed on the build and exposed to the water as well. As I chipped away at the scale I found it went straight in like a worm hole. I got a squirt in the face of sea water from a hole about 3/8 once the scale was chipped out. The area was about 6" below the water line...WHAT TO DO?? There was some empty oil drums in the slipway next to the trawler wharf I was working on. I rolled some over and filled them with water from a hose on the opposite side of the boat from the leak, the list brought the hole above the water (just) and I welded her up. The fishermen were constantly entertained by my wife and I working on WhiteBird!!

Right now I've got a BMW motorbike tank (petrol)that has holed from electrolysis. Weld?? No f%^&$$ way!!! I got some marine tex in from America!!

Alan, So you teach welding? Now I really need to get over there. I have been taught by the best, and my welds still look like a very bad mistake. If you can teach me, you can teach anyone. Machining, and any other mechanical work I can do with the best of them, but something about welding, I just can not seem to develop the technic.
So, back to the question at hand, general consensus seems to be cut an access port, clean it out, and dump the old fuel. Hope that solves the problem. Because of issues like this, I am a big fan of day tanks. I am riggin one on the trimaran. I will have a secondary filter system that will allow me to run either of the main tanks, or the day tank, through either of two sets of filters. If the filter starts to clog, the turn of a valve will switch to another filter, allowing me to change the filters without shutting down, and also buy some time. I do not do well changing fuel filters in rough water. It is one of the few things that still makes me seasick.

[S/V Elusive]

Oye - Thanks Scott - okay .. the 'onboard fuel polisher'. It is an RCI fuel purifier (their title). I bought it over a year ago, and have just now got around to mucking around and installing it. Part of MY problem is that I want to add a couple of manifolds to increase the options of fuel flow (paths: which pick up to use, which racor to go through, leave the purifier in line or out, use an electrical fuel pump to circulate if the engine isn't running).

I've got it all drawn up, it looks real good - actually installing it has been problematic.

I finally decided to go this one step at a time (I KNOW I KNOW - should have done this to begin with). Anyway, I installed the fuel pump and the purifier. I made a simple loop of it: tank, fuel pump, purifier, back to the tank. The quantity of fuel going through the system seemed to be very small and I was suspect of the abiblity of the purifier to do it's job at those low flow rates. Not only that, but after about 30 minutes, the pump would start to get very warm - I don't know if this is normal or if it is good or bad.

During my attempt to remove those damn fuel lines from the installed purifier and pump, I pulled them out of the bulkhead. But that isn't the problem ... I just looped the pump in line with the tank and the flow was the same. I suspect that the pump (Carter 12V2401 - P60378) is just a low volume pump and I should probably get one with a larger flow rate.

I am WAY open to suggestions and thoughts on the pump (both for flow and temperature).

And I'll bet Scott thought I still hadn't started that project. HA!!!

Thomas

Ah, you full time cruiser types have time for all sorts of projects Not sure I mentioned it before, but the flow rate of the pump will be limited by the hose diameter. I know you are working with 1/4" hose on your fuel system, but do you have the option of increasing the hose diameter within the polishing system itself? SOmeone, I think it was Richhh, mentioned earlier that polishing systems rely on high flow to work effectively.

[S/V Elusive]

Yes Scott, we do. But we do NOT have the time to do projects on THREE boats ... lets see... you ARE down to three boats now, aren't you??

Yes... I was aware that I could get an increase in flow using larger diameter fuel hose - I have SOME, but it IS expensive ... and I have plenty of 1/4 inch.

Thomas

Cost over performance. HMMM? Yes, I am down to three. Unless you ask Susan, in which case the dinghys all count. That puts me at 6, or 8 if you count the trimaran as 3

[southernman]

great timing - I have just spent the last 2 weeks doing exactly the above. I've removed engine to get to fuel tanks. Removed the old fuel, drilled 3 100mm holes into tops of fuel tanks, manufactured removable caps, steam cleaned tanks, wet and dry vacuamed tanks, redid engine mounts, painted engine, redid injectors and pumps and put engine back in today, oh and repainted and sound proofed engine bay all in 2 weeks!!

The old fuel was disgusting and was causing us real problems even when we used it on a regular basis.

[Richhh]

Thomas
Consider a Walbro Transfer pump to run your 'purifier'. A walbro is 'almost' a constant duty pump and will need a minimum of 1/2 connections for 3-4 gallons per minute capacity. Dont be 'anal' about elbows, tees, etc. as they contribute to a lot of pressure drop .... long radiused bent copper pipe, although looks like hell, does better from a pressure drop standpoint.

You want a recirculation system to have as high a flow capacity as possible .... it 'turns the entire tankage volume over, faster'. Typically a recirc. filter/purifier retention rating should be 5-10X that of the smallest retention you are using for your 'in-line' fuel filters. ie.: if engine filter is 2uM, use a 15uM on the recirculation circuit.
Every filter has retention capacity in some % efficiency at lower than its 'rated' retention. Turning over the tank many times quickly through the 5-10X will result in a FASTER recovery to the target retention, than if you simply used an equal retention filter of the in-line ... if you use the SAME retention as the fuel delivery system you will take a VERY long time to remove the particles, as the return is constantly diluting the particle count, but isnt flowing very well. The only way to filter a tank in a 'single pass' is to totally filter but transfer to ANOTHER tank, then pump back into the original. Its much faster, more efficient, cheaper to use a 5-10X retention filter in the recirc. line (the 'tech' definition is the exponential rate of decay of particle count distribution).

[DeepFrz]

CaptainJeff; If you take some of the gunk and add a couple of drops of chlorine bleach and it turns white, it is algae. If not, spray a little WD40 on it and if it desolves it is tar. Otherwise it is probably something else.
Phil

[S/V Elusive]

Rich - Great information - Thanks. Another question since you are (now) the defacto expert If I use a larger diameter tube and fitting with my pump (or a different pump) how will that interface with the rest of the tubing throughout the engine fuel system?? Can I have a mixed size fuel system?

To give you a basis of understanding: I intend to be able to select either pick-up port on the tank, option the running through or by-pass of the external electrical fuel pump and 'purifier', selection of one of two racor filters, and the JUST circulation mode - this will all be selectable using valves.

One of your points in your post was that too many elbows/ 't's could severly restrict flow - Am I being too ambitious trying to rig this up to be valve selectable?

[Richhh]

SV Elusive -
I can send you a pdf of my 'ever evolving' fuel system. Send me an email to RhmpL33ATattDOTnet and I'll send you my pdf diagram. A picture is worth 1000 words and this pdf has a sketch and notes/comments. I'll send the pdf to anyone who is interested.

[Starbuck]

Deep,

Thanks for giving me usable information. This thread quickly turned into a pissing contest of knowledge and anecdotes that lost sight of my simple little question rather quickly.

I could not remove my tank because it is glassed into the hull, so I removed the 1 1/2" float assembly cover, pulled out the float, and hand-pumped the 20 gal. out.

I was lucky there were no baffles in the tank, so I had access to the entire inside surface area from that hole. I affixed rags to a straightened coat hanger and swabbed away. Peering through the hole with a flashlight, I discerned a dark crust, less than 1/32 in. thick, on the bottom. It looked just like alum. corrosion, but nearly black. I take this for some water corrosion on the bottom of the tank, since it did not swab off (the deck filler cap is cracked, and it's possible the tank took on some incidental H20 over time: there was about a teaspoon of water in the trap). But I'm not worried about that, since it's not going anywhere.

When the rags came out clean and dry, I poured in about a quart (liter, Alan, BC Mike and Talbot) of paint thinner (mineral spirits) and repeated the mopping procedure, worrying the corners well.

Then I buttoned the tank up, cleaned the water trap again (just a touch of gritty sludge, nothing like before) and fired up the engine.

It ran for an hour, then the newish filter clogged (this filter was spun on mid-way through the delivery, so had about 5 hours on it, total). Another fresh filter, and she ran at the dock 1.5 hrs. w/out a hiccup (no rpm fluctuation) until I happily shut the engine down.

I presume that this filter was the victim of residual grime that had made it into the pick-up hose before my cleaning, and was enough to kill it in its youth.

I'm fairly confident I'm out of the woods now. I bought two extra filters and a new strainer (cannister open @ both ends: the water trap spins on underneath). I'll replace the strainer and be ready for another clogged filter, just in case.

My brother is going to polish my bad fuel. He works in construction, and has a tank/nozzle on his truck for his earth-moving equip. It has a 2 micron filter.

I even kept diesel fuel off of my salon carpet! Not so lucky transporting fuel in the back of my hatchback: smells of fuel oil, so I will have to strip out the carpeting and blast it at the DIY carwash. I don't think Febreeze is up to the job.

[S/V Elusive]

"Captain Jeff Deep
This thread quickly turned into a pissing contest of knowledge and anecdotes that lost sight of my simple little question rather quickly."


Jeff - Not sure where you came up with a pissing contest - I know that I sure as heck know not to piss into a fuel tank. However, it was a fuel contamination and fuel tank question that I had, so I felt free to just jump in.

Since I don't wish to provide excess information to others, I'll take my question off-line and see what I can figure out with those that responded to my particular questions.

Rich - I've sent you a copy of my GIF file of my system.

[DeepFrz]

CaptainJeff, job well done. Congrats.