Add fuel shut-off valve before carb on 5.0L TKS?

[superbenk]

I was thinking about adding a fuel shut-off valve between the fuel/water filter & the carb on my 5.0L engine with TKS carb. The idea being that I could shut the valve off & run the boat out of gas so there wouldn't be fuel sitting in the carb bowl. Is this a bad idea? If not what's the best way to go about doing it & what valve is recommended? Are there any special considerations? Is there any problems with the electric fuel pump in this kind of situation?

 

[bruceb58]

If you really want to run the carb out, just disconnect the the plug on the fuel pump. Personally, I see no need to run the carb out of gas so up to you.

 

[superbenk]

No concerns with E10 gas sitting in there? I put Stabil in the tank for the last few runs of the year so it's stabilized. Maybe I'm just being overly paranoid? I've never had a problem in the past 8+ yrs but...

 

[GA_Boater]

No problems you say. Keep doing what you've doing - It works.

I might look at pulling the fuse or fuel pump relay if you have one. Even disconnect the wire on the oil pressure sensing switch to turn of the pump.

But what you have been doing works.

 

[bruceb58]

No concerns with E10 gas sitting in there?

None...and I don't use any stabilizer.

 

[Pat_220v]

I do not think this would work. Specifically a valve would not let air into the line. It would just stop the gas for flowing in, and out. Similar to how if you take a straw, put one end in water, cover the other end with your finger, and then lift the straw and the water out of the glass. If one end is sealed nothing empties out.


On a side note, I heard once a person should not let carburetor membranes dry out if it can be avoided. I have rebuilt carburetors with dried out and frayed membranes (lawnmower, snowmobile, both 2 cycle), but those could have dried out after they frayed. I have never seen emptying the carburetor of gas as part of any storage manual procedure, but to be truthful I have not dealt with that many engines.

 

[Silvertip]

I do not think this would work. Specifically a valve would not let air into the line. It would just stop the gas for flowing in, and out. Similar to how if you take a straw, put one end in water, cover the other end with your finger, and then lift the straw and the water out of the glass. If one end is sealed nothing empties out.


On a side note, I heard once a person should not let carburetor membranes dry out if it can be avoided. I have rebuilt carburetors with dried out and frayed membranes (lawnmower, snowmobile, both 2 cycle), but those could have dried out after they frayed. I have never seen emptying the carburetor of gas as part of any storage manual procedure, but to be truthful I have not dealt with that many engines.

The idea is to empty the "carburetor" not the entire fuel line. The carburetor is vented and uses a venturi action to draw fuel from the carburetor float bowl. A valve in the fuel line would prevent fuel getting to the carb but the engine would indeed run until the float bowl is "nearly" empty which is the OP's goal. Note the "nearly." You cannot get every drop of fuel out of the carb so the process of emptying is really not necessary. Fuel does not go bad during seasonal layup. Besides, adding a valve introduces another couple of potential points of failure (mainly leakage).

 

[superbenk]

I scrapped the idea & decided to leave alone what wasn't broken. Thanks for all the input & humoring my thought experiment.

 

[Lou C]

Small outboards like our Suzuki DF2.5 actually haves drain on the carb like some small generators. I do drsin this one because the passages and jets in the carb are so small it is very easy to clog. Never drainec the QJet on the OMC and never had a problem.