how to unstuck carburetor after sitting too long

[friendly_jacek]

I tried to start a boat this season. Lots of cranking and no go. Last time it ran good it was over a year ago as I had a lot of problems with faria gauges last summer and had to replace them all.

Fist I though old gas (one year old or so, but with a double dose of Stabil). I drained old gas, added to cars, and put fresh gasoline in the boat. No go (cars run fine 50/50 old/new gas). Checked spark plugs and checked for sparks. Everything looks normal, except sparks were yellowish rather than blue, and one plug was oily (probably from winterizing). Replaced spark plugs just in case.

I think next to work is the carb. I have no experience with carbs. Did anyone fix a stuck carb by some liquid cleaner?

Thanks!!!

 

[abycat]

If you have the coin i would take it to a shop and get them to rebuild it. Chances are some seals or gaskets could be buggered up. Might not cost too much when you look at the bennefits and wont have to worry about the engine not running top notch. or soak the whole carb in carb cleaner for a day or two if you dont want to take it apart. never had much luck with stupid carbs.

 

[toneydoc]

Remove plugs and add a little gas or gas/oil to cylinder and replace plugs.
Then see if is fires and runs for second or two. If it does you have a fuel problem. Could be bad fuel line or carb.

 

[2oldtommy]

Gumout spray cleaner Is the way to go. Spray in the air inlet down the venturies (sp?) and give it another try after waiting a few minutes. If this doesn't do the job, you probably have some internal passages that are gummed up. Try it. FWIW--Oldtommy

 

[Pablo]

So after all the cranking, what do the fresh plugs look like - I mean are they fuel loaded?

 

[friendly_jacek]

Pablo,
They look pretty clean and don't smell like gas that makes me think plugged carb.

 

[Pablo]

Originally Posted By: friendly_jacek
Pablo,
They look pretty clean and don't smell like gas that makes me think plugged carb.


For sure. So if the filter isn't plugged and fuel is getting to the carb, then the jets are plugged.

 

[mechanicx]

The float needle and seat might be stuck not allowing the fuel bowl to fill. Try taping on the float bowl. If that doesn't do it you might try unhooking the fuel line and use some carb cleaner and compressed air to the fuel inlet and fuel bowl vent. Sometimes adding a strong dose of Techron to the fuel will disolve deposits.

 

[friendly_jacek]

Originally Posted By: 2oldtommy
Gumout spray cleaner Is the way to go. Spray in the air inlet down the venturies (sp?) and give it another try after waiting a few minutes. If this doesn't do the job, you probably have some internal passages that are gummed up. Try it. FWIW--Oldtommy


I tried it and the engine fired for a fraction of second on the cleaner fumes and that's it. I tried a few times. Looks like I need to rebuild the carb. Is there anything else I can try before rebuilding?

 

[friendly_jacek]

Originally Posted By: mechanicx
Try taping on the float bowl. If that doesn't do it you might try unhooking the fuel line and use some carb cleaner and compressed air to the fuel inlet and fuel bowl vent.


Will try that too. Thanks.

 

[Chris142]

What kind of Carb is it?

 

[friendly_jacek]

Originally Posted By: mechanicx
The float needle and seat might be stuck not allowing the fuel bowl to fill. Try taping on the float bowl. If that doesn't do it you might try unhooking the fuel line and use some carb cleaner and compressed air to the fuel inlet and fuel bowl vent. Sometimes adding a strong dose of Techron to the fuel will disolve deposits.


Didn't work. I used carb cleaner and B12 cleaner.
I also inspected a fuel filter (inside the carb) and it looked very clean for 9 year old boat (with low hrs).

 

[friendly_jacek]

Originally Posted By: Chris142
What kind of Carb is it?


Mercury Mercruiser Mercarb 2 barrel for 3.0L 4-cylinder I/O.

 

[friendly_jacek]

Here is a weird thing. I sprayed different kinds of cleaners inside the bowl vent several times and the engine would run for a second or two and die. I assumed cleaner in bowl would be used up causing the engine to stop. When I removed the carb, there were fair amounts of gasoline inside that spilled out when I rotated the carb upside down.

Well, regardless, I ordered a rebuilt kit and will work on it. Long overdue after 9 years.

 

[BigCahuna]

Could the fuel be shut off at the gas filter?

 

[Pablo]

Originally Posted By: BigCahuna
Could the fuel be shut off at the gas filter?


I was thinking something like that. Fuel delivery should be verified.

 

[friendly_jacek]

No, fuel delivery was fine. Gas sprayed every time I disconnected a fuel line from pump to the carb. The carb was full of greenish deposits from old/dried gas at the bottom of the bowl and inside jets. Like I said, long overdue for cleaning. I've got it dissembled, except for a couple of screws that don't want to budge.

The lesson learned that even a double dose of Stabil cannot do miracles. I need to find a way to drain gas from carb before longer layovers or find something stronger than Stabil.

 

[sdowney717]

Take it all apart unscrew the brass jets.
You can soak the carb in 90% rubbing alcohol for a few hours.
Get a rubber ear bulb and you can force alcohol threw all the little passages and see how they flow.
Then blow all the passages clean with compressed air.
The alcohol is an excellent cleaner.

If you got bad corrosion inside, then you can soak it in white vinegar for a few hours. Vinegar you should rinse with water and neutralize with ammonia.

 

[SteveSRT8]

Blow too much air through the wrong passage and you can damage things in many carb designs.

 

[friendly_jacek]

Originally Posted By: sdowney717
Take it all apart unscrew the brass jets.
You can soak the carb in 90% rubbing alcohol for a few hours.
Get a rubber ear bulb and you can force alcohol threw all the little passages and see how they flow.
Then blow all the passages clean with compressed air.
The alcohol is an excellent cleaner.

If you got bad corrosion inside, then you can soak it in white vinegar for a few hours. Vinegar you should rinse with water and neutralize with ammonia.


Good tip on alcohol. I will use it for the final cleaning after I remove the stuck and very hardened gaskets. I just purchased some heavy duty paint stripper (same ingredient as gasket remover).

This is what I did so far: first soaked it in boiling water, then cleaned in diluted dishwashing detergent with a toothbrush, rinsed, dried in sun, and finally sprayed carb cleaner through all openings and passages. That removed 99% of the green crud.

I also ordered a gas line valve. I'll put it in series before fuel pump and plan to run the carb dry while flushing the engine. I may also switch from Stabil to Seafom and stop hoarding gas in the boat.