What do you do when you have lot's of time on your hands?

First published in Telltales Magazine. Read, print for your friends, share it, but please don't publish it without written permission.


Gene Gruender
Austin.sailor at yahoo.com

A Fuel System Puzzle
By Gene Gruender
Copyright 1999

As we made a long passage aboard Rainbow Chaser recently we had a lot of time on our hands. Here's proof there was too much free time.

While I was filling the fuel tank - topping off the main tank with all the jerry cans - I got to thinking about fuel. What would I do if I didn't have enough fuel to make it to the next port? What if I was a couple hours short of enough fuel to make it to the dock? My calculations showed that we'd have 12 gallons in the tank when we tied up 2 days later assuming there would be no wind the rest of the way. But, I thought, what if we were a bit short - say four hours worth? What would I do.

To keep occupied the next few hours, I thought about it. Let's assume I wanted to go straight in and keep motoring at 6.5 knots. I burn .5 gallons an hour. (It's really just a tiny bit more, but for the sake of keeping it easy - after all, we were cruising, not straining our brains - I just rounded it off.) For this mental exercise I just wanted to get there, no waiting, no stopping for fuel, no stopping to bleed the fuel system. How would I make up for a 4 hour shortfall in fuel? I thought it could be done. Follow my thinking as I gave it a try.

To begin, you need to know about the boat. I have a 38 gallon main fuel tank. If the boat is bouncing around it will start sucking air when there are about 2 quarts left in the tank. If the sea is still and the boat is not rocking, it will leave one quart in the tank before "running out", however, that last quart will contain some muck in the bottom and won't come out with the normal fuel pickup. In addition I had 7 1/2 gallons of diesel in my old kerosene tank that I converted to a fuel tank. I've already pumped that out into the main tank. There might be as much as a quart of fuel still sloshing around in the bottom.

I've got 6 jerry cans on deck that have been emptied. They might have between a teaspoon and a table spoon in each one if you took some time to drain them.
To figure this out with me, you need to know how the fuel system is configured. Following the fuel system back from the fuel injector pump back toward the tank, there is a hose that goes up to the secondary 2 micron filter on top of the Yanmar. It has a bleed screw on the top. It's worth noting that you must stop the engine to replace this filter, then bleed the low pressure side. There is no other way. From there it goes back down to the mechanical fuel pump, which has a lever to pump fuel to bleed the lines. Continuing from there, the fuel line goes across the engine compartment to a Raycor 200, 2 micron filter assembly, which has a little less than a quart of fluid in it's various parts. The fuel in the bottom is going to have dirt in it. From there it goes back to the fuel tank to a shut off valve, which is screwed into the side of the tank. All hoses are rubber hoses fitted on barbs, held on with small hose clamps. Any can be taken off by loosening the screw of the clamp, then just pulling them off. They could be quickly swapped or moved. All hoses are long enough that they can reach around to a can, the floor, or even around far enough to back into the tank itself.

The fuel tank is 38 gallon tank, triangular on each side, with a flat top. All the triangles lead to a low spot where the fuel pickup line is at. Above it is a hole about 2" with a mechanical fuel gauge installed in it. That is held in place with 6 phillips head screws and can easily be removed. Behind that is a 12" by 12" clean out cover, held in place by 49 10-24 phillips head screws. It also can be removed fairly easily.

I have a couple small hand pumps aboard that I use to move liquids, like engine oil or fuel. They have hoses that can be inserted into things like tanks or jugs, and could be clamped on a barb in place of a fuel line.

There are a number of potential fuel sources on the boat, such as the dribbles of fuel in the various containers, the filters, and the tanks. There are about 20 quarts of various motor oils, 30 to 40 weight, about 12 quarts of used motor oil, 4 quarts of automatic transmission fluid, 15 gallons of pre-mixed 2 cycle gasoline and 2 gallons of 2 cycle oil aboard. There is also some lamp oil, cooking oil and various alcoholic beverages which could all be flammable. There are about 6 extra Yanmar fuel filters and 10 extra Raycor fuel filters aboard.
The job is to figure out how to use some of these the items above to get an extra 4 hours out of the engine, without causing the engine to die, without having to bleed the engine and make it to the dock at the same speed without stopping. Assume the engine hesitated once just seconds ago, indicating it will stop from loss if fuel in a minute or two.

Can it be done? I think so.

Using all this time on my hands, here is the solution I came up with. The first problem is, we don't want the motor to die, so we need to get off of the main fuel tank at once before we suck any more air. I would find a container, from 2 quarts to a gallon - maybe a drinking pitcher, a water jug, whatever I could locate quickly - then put some of the automatic transmission fluid in it. ATF makes a fine substitute for diesel fuel.

I would loosen the clamp on the line going from the Raycor filter to the fuel pump at the Raycor end, then very quickly pull it off and stick it into the pitcher of ATF. This gets us off the main tank, and we are now sucking fuel from a very controlled place I can monitor. If I do it very quickly, very little air will get in the line and it will pass through the injector system with only a slight, brief loss of power. Using whatever I could find, I would secure the jug so it can't fall over and spill.

Using the 4 quarts of ATF, I have found two hours of the four hours I am looking for. I need another two hours.

I have no idea if any of the oil can be used for diesel fuel, so all the oil is of no use to me. The gasoline certainly isn't. I don't know about the cooking oils, so they are no good to me either

I would drain any fuel I could get out of the jerry cans and the converted kerosene tank, taking each and holding it upside down. I'll assume we get a quart of fuel out of those. I would pour this fuel into the main fuel tank. I would then hook the mechanical hand pump to the output of the Raycor, (where I previously removed the fuel line to stick in the jug) then draw out as much fuel as it will get, pumping it into the pitcher that is serving as the fuel tank. Getting the fuel out of the tank this way, it will be filtered and even if we get air a bunch of the time it won't matter. I should get that last quart from the tank that would have had air mixed in if we'd tried to get it with the normal fuel pump, plus the quart we added from the jugs and kerosene tank. Doing it this way, I filtered the fuel that had been sloshing in the cans I found another hour.

Now I'd take the hose loose from the fuel tank outlet, the hose that leads from the tank to the Raycor. I'd bring the end around, remove the mechanical gauge from the fuel tank and stick the hose into the lowest part of the tank. Again, I'd draw the fuel out with the hand pump, sucking it through the Raycor and putting it into the jug that is serving as a temporary fuel tank. This fuel will have a large amount of crud in it as it comes from the tank but will be filtered by the Raycor. It could very well could clog the Raycor filter element. It might have to be changed, but it won't affect the engine. This gives me another half hour. And take note that it is all very well filtered fuel I have put into the pitcher. All of this fuel will all be filtered once more by the Yanmar filter that is mounted on the engine. I've found a total of 3 hours and 30 minutes.

There is still fuel in the Raycor, just a little less than a quart. This fuel isn't going to be filtered. It is going to be a mixture of the fuel from both sides of the filter, so it is not clean. However, since the Yanmar filter is still clean, it can handle a small amount of dirty fuel with little risk, so as the last of the fuel is sucked out of the pitcher, I'd pour whatever is in the Raycor into the pitcher. With this last batch of fuel I am just a few minutes short.

I found almost all the fuel I needed. I almost made it - by my calculations I found all but a couple of minutes of it.

Now, you might ask, is this all speculation? Not really. I've never done this just as I describe, but I've done just about every part at separate times for various reasons. I've run using a can as a fuel tank, using only the Yanmar filter to bypass fuel system problems. I've switched hoses on the fly. I've certainly drained the last of cans before, and I've used the hand pump to move the fuel around. I have used ATF in both my Yanmar and old Mercedes Diesels on many occasions. In fact, the Mercedes garage in Austin is where I learned that ATF makes good diesel fuel. They recommended filling the fuel filters with it when changing them to avoid the bleeding. I've even gotten home late one night when no one was open to sell diesel fuel - a convenience store still had ATF!

There is one addition to add that will apply to many boats. Many, if not most, diesels pump much more diesel through the injector pump than the motor uses. It re-cycles back to the tank in a second fuel line. My Yanmar 3QM30 does not have a return line so I don't have to worry about this. However if your motor does, you'll have one extra step to use these methods. You'll have to locate the return line, remove it and stick it into the jug you are using as a fuel tank so the return fuel goes there as well. Otherwise, you'd just keep pumping the fuel you found back into the main tank..

Even though it was only for fun this time, I hope there is something in here that helps someone get past a problem one day.



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