Siphon/drain Gas from Lund Explorer?

Has anyone siphoned gas from their lund on board tank? I have a 06 Explorer 1700 with the side fill OB tank. I use the Merc stabilizers and fuel conditioners, but just curious how to drain fuel if needed. Haven’t tried to do it yet, but may need to do it in the future to pull out older gas before storage(and replace with fresh), or to run my generator. It may be as easy as putting my siphon tube down the fuel fill and maybe not….

Thanks for any sharing any experience on this.

Reb

Not sure what motor you’re running, but I disconnected the fuel line after the primer bulb, just before it enters the OB, and using a 5 gallon gas can, got the flow started by pumping the bulb, and let it siphon itself. Just keep the 5 gallon gan lower than the boats tank, and raise the bow up to get as much fuel toward the rear pickup.

HRG

I second that method, works great just raise the bow as mentioned above.,

My bad, it’s a 06 Merc 115 4 stroke. I always used the pump/fuel line idea mentioned, but this motor has just a fuel line from the tank with no disconnect like my old OBs. I do have a pretty decent fuel siphon if that will work in the fuel fill. Sorry forgot the motor info.

Reb

Reb:

I pulled the gas line off before the primer bulb, then attached a pump and pulled the gas out that way. I am running Honda tiller…

Mark

You have to plug the vents that are on the side of the boat in order to siphon the gas. On cars the gas cap has enough air to breath through thats why they say only to tighten so many clicks because if its overtightened you create a vaccum in the tank and your check engine light turns on. As gas leaves your tank the pressure needs to be equalized. On a boat this is done by the two vents on the side. In order to siphon you must create a high pressure in the gas tank and laws of pressure kick in. With the low pressure on the outside and high pressure in the tank the fuel is forced out of the tank in order to equalize. If those vents on the side of the boat are open yet, they will vent the pressure you are trying to create inside the tank.

Uhhh…
Siphoning works by gravity, not pressure.

If siphoning works by gravity then, how does fluid go up then come down? Dumping something out works by gravity. Here is part from Wikipedia:

In practical siphons, atmospheric pressure pushes the liquid up the tube into the region of reduced pressure at the top of the tube in the same way as a barometer, and indeed the maximum height of a siphon is the same as the height of a barometer, because they operate by the same mechanism. The reduced pressure is caused by liquid falling on the exit side.

When both ends of a siphon are at atmospheric pressure, liquid flows from high to low. However, if the lower end is pressurized, liquid can flow from low to high, as in siphon coffee. While in everyday siphons, atmospheric pressure is the driving mechanism, in specialized circumstances other mechanisms can work – in the laboratory, some siphons have been demonstrated to work in a vacuum[1][2][3][4][5] – see vacuum siphons – indicating the tensile strength of the liquid is contributing to the operation of siphons at very low pressures. Most familiar siphons have water as a fluid, though mercury is often used in experiments, and other fluids such as organic liquids or even carbon dioxide can be siphoned.[6]

If you don’t have a bulb on the line, in the case of an efi motor, all you need to do is pull the line off at the outlet. Then add another hose with a bulb and syphon away. There is no need to plug the vents, if you do this without pressurizing the system you will get absolutely nothing coming out. No air venting, no gas!

Last winter when I took my boat in,I pulled the fuel line off right at the primer bulb and put a longer hose on it,got the fuel flowing and emptyed my tank,as long as the end is below the fuel tank,thats what creates the drop in presure,they tipped the boat over to refinish it.
Stan

This was directed at siphoning by using a hose down into the tank not pulling the fuel line to the motor and letting it drain. I would pull the fuel line it should disconnect somewhere and I think it would drain the fuel that way. You never can get everything from a siphon.

Quote:

---

If siphoning works by gravity then, how does fluid go up then come down? Dumping something out works by gravity. Here is part from Wikipedia:

---

I’m not going to get in a pissing match with you, but your “article” cites atmospheric pressure as the driving force behind siphoning. Atmospheric pressure means the pressure in the tank is ambient. You suggest that you need to create high pressure inside the tank to siphon gas out–the tank would not be at atmospheric pressure then.

Think of it this way. I can siphon water out of an open 5-gallon bucket as long as the source is elevated higher than the output; there is no need to create positive pressure in the source vessel.

Sorry to the original poster here.

Thanks for all the replies. I’m going to try the fuel line disconnect ideas this weekend. Otherwise, has anyone tied just siphoning from the fuel fill? Please be respectful to each other. We are all learning in one way or another. And we have Lund boat inerests in common.

Thanks! Reb

I tried siphoning last fall I could get the hose down the tank far enough. However my hose was pretty weak and I didnt try to long.

You would need a pretty long hose to get all the way inside the tank. You could do it, but it would be difficult. Using the main engine outlet on the inside of the splash well is the way to go.

I had tryed to go in thru the fill hole but it turned out to be a lot of work for no results,thats why I went to the fuel pickup.
Stan

I know this is really old but I’m trying to drain my fuel again and won’t siphon from the tank outlet in the splash well. I’m using a fuel line/pump bulb from our 10hp outboard. The bulb does not seem to pump any fuel from the tank after 20-30 pumps gave up. Is there a better/safer way to pump the fuel?

As I recall in 2013 I had to keep pumping a bulb from the 10hp fuel line and it did not siphon just had to keep pumping (hose all down hill to tank below boat hull. That took forever. Now here I am again and can’t even get the bulb to pump the fuel.

Are there any safe/electric fuel pumps I could use?

Do you have the fuel selection valve on your Lund that says main/reserve. I know when I did this a couple years back if it was not in the right direction I would not get flow. Or if I spun it more than 360 it didn’t flow right.

There are several pumps out there made for this that don’t cost a lot. I borrowed one from a friend this spring and pumped out my boats and snowmobiles.

Flowjoe.com is the brand I used, they have a couple different options. I’ll probably buy my own this fall.

Thanks guys,
I don’t have a reserve tank, just single built in. I found a leak in the bulb I was pumping with. I did get a new prime bulb and put it further down line (low near gas can filling) and it worked for siphoning (as I type it’s siphoning).

The fuel coming out is pretty yellow/orange in color (more than normal). I really should have done this earlier. I hope to be able to pump/siphon most out today and put some fresh fuel in and see if it will bog down and go into protect mode as it has been. I’m also going to replace the fuel line from the boat tank to the motor while I’m enjoying this project.