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Discussion Starter · #1 ·
As part of a separate transmission cable replacement issue, I decided to hire a mechanic to rebuild my gunked up carburetor. In hindsight, I wish I had done it myself, but that is another story.
The engine now fires up on the first crank, but it wants to rev up high, and there is a lot of blue smoke coming out of the exhaust. There is also what appears to be a gas slick forming on the water behind the exhaust. And it sounds like it is spark knocking.
The oil pressure is 40 psi. No water in the oil, and the level hasn't dropped. The plugs look ok, except for two that are a bit black and dry(I am assuming from having to run it for an extended time with the choke, from a gunked up carb?).
Now the cabin of the boat smells like gas, and there appears to be a gas-like residue on the OUTSIDE of the carb and underneath it. The mechanic swears that there is a valve or piston problem and that the gas slick is an oil slick, but I know for a fact that it wasn't smoking/knocking/slicking before the repair.
I would greatly appreciate any insight on this problem. I will be checking the compression on the next trip down to the boat.
 

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Discussion Starter · #16 ·
I went down again this weekend. The smell in the boat wasn't quite as bad, but when the bilge pump kicked on there was more residue on top of the water when it exited the boat. I know now that shutting the gas petcock should be done after each trip. I traced every line and every connection, looking for a leak. I am in agreement with you folks that there is a float problem. I did not start the engine. The carb had some wet residue on it, so I cleaned it up and also the area underneath it. I left a clean white paper towel. If that thing is stained next weekend, then that HAS to be it. Either way, I know I need to pull the carb.

ALSO, the mechanic failed to seat the choke cable bracket correctly. Not sure if this has anything to do with it, but I thought I would mention it.

Thanks again for your advice.
 

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Discussion Starter · #24 ·
Pulled the carb this weekend. Was easier than I thought.
More gas found under it again. This time I left absorbent pads and sealed off everything, just in case the local insects were looking for a nice nesting spot.

Going to take it apart. Thanks again to all for your advice. The one thing I can't understand is why is it running rich while ALSO having a leak? Could a high float level cause leaking?
 

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Discussion Starter · #28 ·
Update: took the carb apart and examined it closely. The float was indeed functioning. I also pushed the float down in a cup of water to see if it had any leaks. No leaks. Put it back together and installed it.
The engine fires up, runs steady (no more knocking), but still smokes. There is also what still appears to be some oily residue on top of the water from the exhaust. The oil pressure was steady at 40 psi. Oil level the same- not drinking oil. Set the mixture screw to one and half turns out. Tried turning it in half a turn and also the other way a half a turn. Doesn't stop the smoking/oily residue. I can't figure it out. Left absorbent pads under the carb. Going to see if it is still leaking on the next trip.
I guess checking the combustion is the next step. The only other thing I can think of is the Marvel Mystery Oil that is in the gas. I add a few ounces per gallon.
 

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Discussion Starter · #31 ·
Yes, it is like cooking with wine- very easy to add too much!
Thanks for the tips, not giving up on this thing yet.
Would it be safe to disconnect the fuel line from one side of the engine side of the Racor filter and put the fuel hose down into a 2 gallon gas tank? I could plug the Racor and move the gas tank into the cockpit, away from any possible sparks.
 

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Discussion Starter · #33 ·
One final update- something told me to try pulling the carb one more time. Downloaded the carburetor video from the Moyer site, which actually addresses quite a few frequent issues. Removed the float valve seat and blew on it by mouth. Also used a sharpened dowel to clean out any tiny grit. Something must have worked right because she ran much better this time. No blue smoke and no residue on the water. After about one minute, however, a bunch of RUST came out of the exhaust, and then water stopped coming out.
Blockage in the exhaust or somewhere in the cooling system?
 

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Discussion Starter · #42 · (Edited)
This particular engine has FWC and electronic ignition.

The manifold doesn't look particularly difficult to remove, but I said the same thing about the thermostat housing!
Just remove the rear two bolts holding the exhaust, the carb, and two hoses, and then the manifold, right?

I was thinking the Dremel might do a good job of polishing up everything, no?

Edit: Oops, looks like I may have to drain the manifold first, some great stuff on this site:
http://www.weliveonaboat.com/2006/12/winterize-an-atomic-4.html
If the site owner is also an SN member, then thanks for the pics on your site!
 
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