How many remove fuel line?

[sparky]

Just wanted to find out how many people unplug their fuel line and let the motor use up what gas is left in the engine. How long between trips when you do this? The reason I'm asking is that I'm in the market for a new motor and after visiting a lot of boards and doing research I see where some of the smaller motors are having trouble with varnish coating the insides of the carbs. I fish a lot so old gas is not a problem. I usually put in 5 or 6 days a week through the summer and fall until ice up. My last motor a Johnson never had any carb problems for the 20 years that I own it. It was always hooked up. Is this something that needs to be done with the newer models of motors?

[Scrapper]

Run seafoam or something of similar you shouldn't have any trouble. If you use a premix engine I do not recommend running the carbs dry...ECSPECIALLY if you have more than one carb. The carbs are inline...meaning one normally gets fed before the others...your oil is in your gas...as the first runs out the others keep the engine running...hence dry holes on the empty carb. Also when you run your engine dry you have a dry start until fuel gets pumped in. Four strokes it doesn't matter. Anything premix I would not do it. Oil injected engines that mix oil in before the carbs..most of them...will also do the same. Just my .02 cents. Some carbs get fed at the same time...but you still have a dry start. You also will get dried seals eventually from doing this...ie...float. Just some thoughts. Just run some good staiblizer or fuel additive...

[CatFan]

I've always been told not to do that because when the engine runs out of fuel, it runs out of oil. That said, most larger outboards don't even have the connectors on the fuel lines anymore.

[The Marine Doctor]

Scrapper, I am going the opposite way with this one.

When running an engine out of fuel at idle, it does not necessarily mean all the fuel has been pulled from that cyl...or that its running dry. It simply means that there is not enough fuel for combustion to take place.
Under normal conditions and idle speed, most engines will die if one carb drops out.
IF ran at high speed and out of fuel...then there may be concern for premature engine wear.
Having torn down hundreds of engines, I can tell you that there is tons of fuel always sitting inside the engines.

I know this is opposite but...

Now lets have a look at the inline 6 from Merc.
For starting purposes the top 2 carbs are choked while the bottom is not.
It is not until the engine starts that you can hear the bottom cyls pick up.

As for J/E oil injected engines, if you disconnect the fuel line you risk damage to the VRO and flooding the carbs with oil.
Other versions of oil injection will just push oil through.

TMD

[Flatwater]

single carb, small outboard. If I think it may be over 2 weeks prior to next use I pull the fuel line and run her dry. For my 9.9 4 stroke it is a MUST!! Carbs contain aluminum and ethyl alcohol dissolves aluminum, new gas contains 10% ethyl alcohol. It causes white powder stuff (aluminum oxide) in the fine lines in the carb thus clogging it. If I get time I will post pictures of a carb that is not rebuildable that is only 2 years old. Unable to get the white stuff out. $405. for a new carb.!!!! plus labor to try to rebuild the old one and end up installing new one. I still have the old one to show folks, proof is always in seeing. or is it seeing is beleaving?

[The Marine Doctor]

What Mercury actually recommends now.

Drain the carb.
Force high pressure air into the float bowl via the drain hole...this gains access to the jetting and clears them for storage.

I have too seen the white powder in carbs.

TMD

[sparky]

That's what I read about the 9.9 that you have to run the carb dry. Just seems that it's a waste of gas if your going to use it the next day.

[The Marine Doctor]

Running the carb dry can cause problems with the fuel pump diaphragm.

I know that the owners manual says its OK...but its not.

I would not advise to do it that way.

TMD

[Scrapper]

I agree Doc...guess thats why you can actually get one to hit after it runs out of gas by choking. Just scares me is all...lol.

I also agree on the fuel...todays fuel STINKS!! And continues to get worse. Now they want to pass it to 15% ethanol...read that in the paper this weekend. Whats a boater to do!?!?! LOL...Gotta love the way the world turns. :rolleyes:

[thudpucker]

I have several John/rudes and a Mariner. The books tell you to run the engine out of gas.
On my Mariner the P.O. used that Stabil in the tank and ran it through the engine.
It softend up the Rubber tip on the Needle valve.

For a long time I never knew why it wouldnt start after sitting. I finally found out the softend rubber tip on the Needle valve was being held up into the brass boss of the fuel inlet if I left the engine with fuel in the carb.
Driven up so hard it reformed and stuck up there. So hard I had to take the fuel line off and blow with a lot of pressure to drive that Needle valve out of the fuel inlet.

I finally read the Manual that came with it, and it told me to run it out of gas. I started pulling the Fuel line off a few yards from the beach and let the engine run itself out of gas. Three years now, and no problem since then.

I really never had that with all my Jon/Rudes though. But I cannot remember any of my Jon/rudes haveng that accursed rubber tip on the Needle valve.