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Author Topic:   Disconnect fuel line and run gas out of outboard between uses?
Kelly posted 05-21-2004 10:00 AM ET (US)   Profile for Kelly   Send Email to Kelly  
Growing up, we had small portable outboards and would always disconnect the fuel line and run the gas out of the motor after every use. We would actually figure out where on the lake we needed to disconnect the fuel line so we would run out just as we reached the dock. It seemed to keep those motors in good working order.

Is it necessary or a good practice to run the fuel out of carbed outboards in the 90 hp range, or does it cause some other problem? I just had the carbs rebuilt and would like to take as good of care of them as possible.


JohnJ80 posted 05-21-2004 10:12 AM ET (US)     Profile for JohnJ80  Send Email to JohnJ80     
In my experience it isn't necessary for larger engines. I have a 2HP Honda kicker for my sailboat that you have to do that through for the simple reason that the jets on the carbs is so doggone tiny - you can hardly even see the hole. It plugs easily. So, for that engine, running the gas out is important.

That all being said, two different small engine mechanics that I consult with regularily tell me that with the new blends of gasoline, they varnish and go stale much easier than years ago. They recommend stabilizing any gas in any tank that will not be consumed in a week or two. Their feeling is that the gas starts to get undesirable in a month or so.

I think that is reasonable advice so if I won't be running the tank through the boat in 2 weeks or so, I put in the stabilizer. It doesn't seem to hurt the performance at all. In fact gas that is in the boat, but stabilized over the winter seems to run just fine. In fact, I keep a can of Stabil in the boat for just that reason, I do it pretty much every other time I gas up at the marina.


BQUICK posted 05-21-2004 11:48 AM ET (US)     Profile for BQUICK  Send Email to BQUICK     
Seems to be a waste of gas and if 2-stroke you are running the motor out of oil also.

As far as gas going bad.....I worked at a Merc dealer and we asked a rep about the Quicksilver oil as to whether it contained preservative and he said it did contain we had suspected since mixed fuel seemed to last alot longer than just gas.

JBCornwell posted 05-21-2004 09:56 PM ET (US)     Profile for JBCornwell  Send Email to JBCornwell     
On a single carb engine without oil injection it is probably fairly harmless to do this.

On multicarb engines without oil injection it is a bad idea because one carb will go dry before the other(s) and it's cylinder(s) will be run dry. Damage is likely over time.

On any oil injected engine it is a bad idea because either the carb(s) or the crankcase will be loaded up with excess oil. Plug fouling is almost a certainty.

Short answer is don't do it.

Red sky at night. . .

Dick posted 05-21-2004 10:13 PM ET (US)     Profile for Dick  Send Email to Dick     
I recomend runing a fuel stabilizer at all times. It can't hurt and can only help. I am a Merc man but I like the Bombardier 2+4, with it I see no reason to run the carb/carbs dry.
AQUANUT posted 05-21-2004 11:54 PM ET (US)     Profile for AQUANUT  Send Email to AQUANUT     
okay check this out...just reieved a mercury tech bulletin
that says running a carbed engine out fuel,2 stroke and 4 stroke, with the intent of puuting the engine in storage for any length of time is not advised. The explanation is, that mercury has found that drying the carbs out...causes the internal parts..jets,seats,and gaskets damage.,,,the gaskets...dry out..contract..leak..internally to the carb.
fuel exsposed to air, becomes varnish quicker...

saw it in black and white...

Kelly posted 05-23-2004 10:27 PM ET (US)     Profile for Kelly  Send Email to Kelly     
Thanks for the replies.
BQUICK posted 05-24-2004 10:34 AM ET (US)     Profile for BQUICK  Send Email to BQUICK     
That's what I suspected.....if a small amount of gas remains it will turn to gum/varnish soome due to greater surface area per volume. Think of this....if you have a cup of gas full vs. just a little on the bottom, the small amount will turn nasty alot sooner. Just over one winter.....

On the other side of the coin.....if a motor is going to be stored for say 5 yrs w/o preservative in the gas and it is put away with full carbs....there will be a whole lot of gum/varnish. (even with presevative after 5 yrs it not going to be pretty) that case I would run the carbs dry WHILE fogging so oil is on the parts and deal with a small amount of gum/varnish in 5 yrs.

Salmon Tub posted 05-24-2004 02:51 PM ET (US)     Profile for Salmon Tub  Send Email to Salmon Tub     
Hey Aqua, could you do me, or more exactly, a buddy of mine, a favor and give the link to the tech bulletin. My buddy has a carbed 4 stroke 90 Merc. It is a few years old, and still under warranty. His motor wouldn't start so he took it to a dealer. They fixed it but hit him up for $700+. Said that the carbs had not been run dry, and since he didn't use the motor for a month, the fuel dried up and fouled the carbs to the point that it wouldn't even start. I think that they used the 'ole' old fuel 'line' so as to be able to avoid a warranty job. (both puns intended). Thanks!

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