How-to Drain a Diesel fuel tank?

AXEL · May 7, 2009

I've used that handy little pump by Jasco that fits on your electric hand drill. Do not buy from West Marine. They want $50 for it. Defender sells it for $35. A little pricey but it does the job. You can also use it to change oil and transmission fluid. If your engine is starving for fuel you obviously need to change fuel filters. You may want to try this first. I have a '77 C30. The fuel tank is very accessible. In fact I have had it out several times over the years to clean it out. If you can get at the top of your tank you may want to tank the top fitting off (it's about 3" in dia) and look in there and make sure there is nothing funky growing on the bottom of the tank.

sailingdog · May 7, 2009

It could be bad fuel, it could be an airleak in the fuel lines. Before going to the trouble of draining the fuel tank, I would recommend you try getting a small jerry can of fresh diesel and dropping a fuel line into it and see if the engine runs with the good fuel. If it doesn't, chances are good that you have a fuel system air leak. A common point for this to occur is the banjo bolts. If you over tighten them, the banjo bolt compression washers can deform and cause a small air leak.

If the system runs fine on the fresh diesel, then the problem is likely the old fuel, and emptying the tank, and cleaning it out is probably a good idea.

Another common issue is the pickup tube. On some older fuel tanks, the pickup tube has a screen on the end of it...and this can clog and cause the engine to run for a while and then die. Removing the screen is often a good idea, provided you have a decent primary and secondary fuel filter installed in the fuel line.

BaySailerBill said:
Hi All,

My 1984 Catalina C-27 has been on the hard for two years and the fuel needs to be replaced. I don't think the last owner did anything to the fuel or the tank when they put her in storage. The tank reads half full (18 gallon tank) but the engine won't stay running. It seems to be starving for fuel. I strongly suspect the fuel is bad and needs charging.

My question is, does anyone have any suggestions on how to drain the tank?

Thanks,
BILL

Richard Bryer · May 7, 2009

I drained the fuel- almost a full tank- out of my H34 on the hard by removing the filler hose at the tank and the scupper drain hose, inserting a length of garden hose and running it out the scupper drain and into a clean new plastic garbage can. Use caution when sucking on the hose to start the syphon or you end up with a mouthful of diesel. The scupper opening in the transom of the 34 is lower than the fuel tank so this worked fine. I did try to syphon up and over the side- just could not get enough suction!

Rob19574 · May 7, 2009

Bill - If you have a removable paddle-wheel or Depth-Finder transducer in your hull here is another tip: Use Richards suggestion above. Then remove one of the transducers in the hull and run the hose out and down through the opening to a portable tank on the hard. It will give you a good siphon and avoid any spills in your boat.

- Rob

Tim R. · May 7, 2009

All diesel tanks should have an inspection port in order to see the inside of the tank and to clean it properly. Removeing the fuel does not clean the tank. The stuff that grows in the tank tends to stick to the bottom. You need to get in there and remove the scum that accumulates and sticks to the bottom of the tank.

I clean my tank every year and put in fresh fuel every spring from a reputible supplier. The fuel I removed last week had the scum in it that I broke loose from the bottom of the tank. I then poured it into my home heating oil tank through a built in screen on my jerry can. The weight of 5 gallons of fuel was not enough to overcome the blockage on the screen. I had to keep cleaning the screen to get the fuel to flow.

BTW, the only reason I had this scum is because I decided not to clean the tank last spring as it was realtively clean already when I inspected it.

Also, in the 4 years I have been inspecting and cleaning the tank I leave it go over the winter(5 months) with about 5-10 gallons in a 40 gal tank and have never once seen any evidence of moisture. The tank is vented to the outside the entire winter.

higgs · May 7, 2009

I would also check the vent. Spiders are notorious for bulding nests in them and plugging them up.

AXEL · May 7, 2009

Besides the pickup tube check the petcock or shut off valve on the tank if you have one. This valve is usually a 90 degree bend. I had a problem a couple of years ago with fuel stravation to the engine. I took the fuel line off the fuel filter/water seperator and blew back into the tank. I felt a restriction. I passed a pip cleaner through the valve and broke lose the problem. After that the engine ran fine.

Idratherbesailing · May 7, 2009

Old fuel is rarely the problem

I'm an old farmer, and I've seen a lot of engines run on very old diesel. Generally, if the fuel is not full of water, the age of the fuel is rarely a problem for the typical low hp/liter diesels found in sailboats. The problem is that it looks bad or smells "wrong", but it will run the engine, although you might have to drain the water collector or change filters at some point to use it all. Pumping it out as much as you can and then filling with fresh diesel is usually a very practical solution, although if you have the bucks/time, it is always better to remove the fuel and clean the tank and put in fresh fuel. But you would be surprised what a diesel will run on if you have a good filtration system to remove the water and gunk before the injector pump. Of course, most of us would rather work on our boats than use them, and I can verify that changing out a full tank of fuel and scrubbing the tank is a lot of work.

Now if you have a modern "common rail" electronic diesel, and the associated filtration system for that (see www.boatdiesel.com) , you definitely want to keep your fuel system almost antiseptic. But older, smaller horsepower diesels are surprisingly robust when it come to fuel quality. For many years, I ran a series of Perkins power units that drove irrigation pumps. 500 gallon tanks, left out in the rain 24/7, sometimes would not use the fuel for a couple of years because rain was adequate, and we would change filters on the tank and engine, and run the fuel that was at least 2-3 years old. Note, this was on an older diesel, and I would not be so cavalier about using old fuel in a "common rail" electronic injection system, but most of our boats don't have that problem. My opinion only, and worth what you paid for it.

Steve Dion · May 7, 2009

Bill: I am with Jim Logan on this. I think your engine will run fine on the old fuel, but you really need to find out why it is starved for fuel.

It is not that difficult to suck the old fuel into a container or two. Take it to your local fire department. Those guys love to use old fuel to light their practice sites on fire. Then you should clean out the tank the best you can.

You want to be sure that your filters & lines are not filled with contaminated materials too. It makes a good excuse to replace any old fuel lines/filters. I would also suggest that you remove the fuel pickup line. Some boats have a screen on the end of the pickup tube. The screen may be restricting fuel flow.

One of the BEST things to clean out a diesel fuel tank is Bio Diesel. The only problem with this stuff is that it cleans almost too well and can end up causing fuel leaks in rubber seals and hoses. If you put a gallon or two in the tank and let it sit for a couple of days you can pump it out at the dock after you run the engine for an hour or two and then refill the tank with new fuel or just add the new fuel to the existing Bio.

Check out the obvious before you get started. If you have an air leak, it may appear as a fuel problem too.

druid · May 8, 2009

I have a question: what the HECK do you do with the old diesel once you've drained it? I have about 40 litres of really old diesel that I don't trust to run in my new engine. None of the recycling depots in Greater Vancouver will touch it (OK, one. but they have a flat rate of $100 to dispose of it!

)

I'm told I can use it to start fires, but I don't start that many fires...

druid

Dan Johnson · May 8, 2009

Druid...

Diesel doesn't "go bad" like gasoline. Run it through a filtration system like a fuel polisher to remove any moisture and debris and then burn it in your home oil heating system or sell it to a contractor for his dozer or a farmer for his tractor. Or put it back in the boat's tank and not worry about it if you have good filtration on the boat.

jackhartjr · May 8, 2009

Druid...give it to a trucker!
Jack

Steve Dion · May 8, 2009

Fire Departments will usually take the stuff. The land fills will also take it and put it in their equipment.

You can always run it through a Baja filter and recycle it too.

DougM · May 9, 2009

Check your fuel lines. they may look fine, but if they are as old as the boat they may have minute cracks that and after changing filters etc., that was the last thing he looked at. It turned out to be the problem.

Prime Time · May 9, 2009

Options

You can add it to your home furnace tank and burn it. Our local boat yard recycles it.

druid said:
I have a question: what the HECK do you do with the old diesel once you've drained it? I have about 40 litres of really old diesel that I don't trust to run in my new engine. None of the recycling depots in Greater Vancouver will touch it (OK, one. but they have a flat rate of $100 to dispose of it! )

I'm told I can use it to start fires, but I don't start that many fires...

druid

frenzy13 · May 10, 2009

Bill

I have a Catalina 27 1986. I have drained the fuel tank several times using the electric fuel pump. I disconnect the fuel line at the filter and put it in five gallon can and turn on the pump. The pickup tube in my boat is in the lowest part of the tank. I removed the tank a few year ago. I was able to drain all but less than half a coffee cup of fuel from the tank. After using the pump check the pump filters and refill the tank. If you don't top it with fuel the tank will fill with water over the winter.

Bob

jaysweet · May 10, 2009

but which pump to use...

Getting back to the question "how to drain the tank": we have a tank which will never have access for an inspection port, short of removing the whole tank. (It's tucked back in the stern, with side-only access by removing a panel in the aft cabin. No top access and no hope of any.) So I think feeding a hose (or rigid plastic tube) down the fill port is the only reasonable way to go. But I'm a bit stuck on exactly which pump to buy.

I don't want to buy a $150 electric fuel pump. The most reasonable options seem to be an electric drill pump (but then I still need to buy all the tubing, etc.), or better yet (I think) one of these:

WEST MARINE Manual Oil Change Pump

This is one of the hand-pump vacuum type systems. We already have one we use to change the oil, and it works well. It has the rigid tubing, plus all the flexible tubing, plus a tank to catch the diesel. Anyone see why this is a bad option? Also, if it would work, should I use the one I already have, or should I buy a new one just for the diesel?

Jay

svenusa · May 10, 2009

outboard motor primer bulb

Worked for me in the past.. Push a length of tube (from pep-boys) down the filler hole, and pump the primer bulb with your foot into a jerry can. I drained a 60 gallon tank on a powerboat on my driveway this way, in maybe 45 minutes.. I would imagine your tank is only 10 gallons or so anyway. Frenzy is right make sure to fill the tank when done or it will fill with water from condensation.

How-to Drain a Diesel fuel tank?

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