Running gas out of engine

Sunbird22358 · Jun 3, 2013

I wouldn't do it EVERY time I used the engine, but end of season and each time I was done using the boat for more than a day or so I would do it as well. Gas today, with the added ethanol, can go sour in a short time, gumming up the carburator. Also, the gas can evaporate leaving just oil, which may clog the sparkplugs on a 2-stroke engine. So, not as critical on a 4-stroke I guess, but I still consider it a good idea to burn out the gas left in the engine each time that i put the boat away for the night/week. I would not do this after just powering out of the harbor with intentions of using the outboard later..... draining the gas from the carb MAY result in the engine not being as ready to use in an "emergency" during the voyage. When starting out each day, I figure that just connecting the fuel line ot hte outboard will "prime" the system enough for use, especially if the bulb is squeezed a few times to be sure. We never had a problem on our previous boat doing this and I have never had a prblem due to this practice on my present boat.

Stu Jackson · Jun 3, 2013

Only need to do so for extended periods of engine inactivity. I consider that to be when I lift the engine off the dinghy and put it on the bracket on the pushpit, so when I use the earmuffs to wash out the salt water, we run the carb dry. It's an Evinrude 9.9 hp 2 stroke, 1990.

oldersalt · Jun 3, 2013

I've got a 2008 Honda 9.9. When taking the boat out of the water for more than a day or two, I just disconnect the fuel line at the engine while the engine is running (this is perfectly safe) and let it idle for several minutes until it quits. In the meantime I'm getting the trailer into the water so no time is wasted. When launching the next time, I reconnect the fuel line and pump the bulb until it shows some resistance. Engine always starts and runs fine. I'm not sure that the ethanol would cause any problems in such a short time sitting inside the engine, but I figure this is a good example of "can't hurt; might help."
Fair winds,
Oldersalt

Spindrift NH · Jun 3, 2013

Something to consider is the fact that each time you are running the engine out of gas, you are running it lean. Lean running engines tend to end up with scored pistons. After working in a small engine repair shop, which by no means is a qualifier for an "expert mechanic", I stopped running my personal engines, chain saws, trimmers, roto-tillers, and outboard motors dry.
While it is true that ethanol gas goes stale in a couple of weeks, a worse problem is water in the gas. Ethanol attracts water. If you're going to let gas sit for a while use a good gas treatment, like Marine Stabyl.

anchorclanker · Jun 4, 2013

Yeah, running lean is BAD. But only for extended periods. The one or two seconds its stays running as it goes lean running out of fuel is not going to harm it.

Honda's, and many of the other foreign makes, have a carb drain screw. You may see a length of hose coming from the bottom of the fuel bowl and a screw at that fitting. Best to look at a parts diagram/owners manual, but its likely a drain.

On domestics, tilting the motor all the way up will generally empty the carb. But in all cases, or in either case, its best to run your motor out first, by disconnecting the line, so you dont spill so much fuel in the water.

Brian S · Jun 4, 2013

anchorclanker said:
On domestics, tilting the motor all the way up will generally empty the carb. But in all cases, or in either case, its best to run your motor out first, by disconnecting the line, so you dont spill so much fuel in the water.

Oh, heck, on my Suzuki 2 hp 2 stroke, tilting the motor ENSURES that any fuel in the bowl runs out the air intake, and stinks up the rest of your day!

I run the gas out of that motor every time I use it. I have to motor out from the launch ramp, shut off the fuel petcock and leave it running while I hoist the main, and let it die before I tilt it up for sailing. And then for good measure, I spin it around once hoisted so that the air intake (front of motor) is pointing upwards. Nothing worse than a run back home, where the wind on the stern keeps the gas fumes in the boat!

Brian

Joe11688 · Jun 5, 2013

Last year I had a lot of work done to my engine which involved replacing the water intake tube and making the needed repairs as a result of the engine overheating. Outside of that, my 1999 Johnson 8 hp two stroke has always ran like a top.

When I went down to pick up my engine, the mechanic told me to replace the old rubber fuel line with a new alcohol resistant line. Ethanol can eat out the rubber and cause some big problems to the carburetor, so I'm told. He also told me to disconnect the fuel line and let the engine run out of gas whenever I put my boat up for the day. My friend Wayne does this to his engine but I've never done it and my engine has always run great. Of course, at the end of the season when I fog my engine I do this before storing the outboard down my cellar.
Anyway, I took his advise and started doing this last year. After a few times, my engine started running lousy so I just made up my mind that I'm going to stick with what has worked for me for years now. The fuel line stays connected for now on.

One thing I always do before starting the engine the next one or two days that it hasn't run is; I always open the fuel compartment and lift the tank and shake it a few times to make sure that the oil stays mixed with the gas. I don't have a Gasoline/water separator gadget in my fuel line and I'm not apt to get one. If I had a built in fuel tank I'd be forced to purchase one and install it.
I know that my mechanic is very knowledgeable but I think I'll pass on his advise and just stick with what has worked for me for many years.