Rebuild Carbs, or Leave Them Alone?

[BMarkey]

In another thread, I had a lot of trouble with getting my 115 Johnson started afer sitting ahile and getting a lot of water in the gas.

I wanted you all to know that taking the adult-ed marine engine maintenance class at South Tech Academy in Boynton has so far been very helpful. In the first three of nine three-hour classes, I have checked the compression (solid at 150), spark, fuel (had to pump a lot of water out, dump the fuel filter and replace the filter, primer bulb, etc.) and carbs. We drained the four carbs and since then, the engine has run well.

On Thursday, we removed the lower unit and replaced the impeller, cleaning up the water pump, plate, etc. (It's a good thing I did this, because the old impeller was really chewed up. I had to cut it apart to remove it. It pumped fine and I had no problems, but that disaster was not far off.) And new lower unit grease was installed. The teacher blew out the water pressure hose and found the gauge to be bad.

Anyway, I have wanted to remove the carbs and clean them. The teacher agreed until he heard the engine and said they didn't need to be rebuilt. He recommended that I buy the complete kits if I wanted to re-do them (after he had a mess with another student's gaskets, etc.)

Anyway, here is the question: Take off and try to clean up the carbs really well; buy four kits and rebuild them; or leave them alone until I have trouble?

My first thought was to do the carbs just for the sake of my knowledge and the class?

Your opinions?

BTW, where is the least expensive place in SoFla to buy the carb kits?

[BMarkey]

The engine has been running well - in the yard. So, I took it out today from Currie Park in West Palm Beach (those "helpers are back in force and are pains in the ass). All was fine until I tried to get in a plane. The engine lost power, then sputtered, then died. That was it.

Luckily, I had gone south and the wind blew us all the way back, right to the ramp.

I didn't figure that I still had some water in the tank, and that when the boat's steep angle caused the gas to move to the rear of the tank, the water would be fed right to the engine.

So, I pumped and pumped out the gas again (from the primer bulb), getting a half-gallon or so of water in all. All looked good, but I went ahead and emptied the tank, putting the "good" gas aside for use in the mower and weedeater. I bought some Star-tron for the heck of it and in 8 fresh gallons of gas. I drained the carbs, drained the fuel filter a couple of times and then installed a new filter. The engine came back to life and kept running, even when I tilted the boat on a crazy angle to force everything to the back of the gas tank.

Now, will it run in the water?!

[BMarkey]

I am still fighting with a water-in-the-tank issue. In two water tests in the Intracoastal last weekend, the engine would fail when I went to a plane. Water was clogging the fuel as the boat angle changed.

I emptied the tank (completely, in a long, tedious process) yesterday and dumped little bits of water out of the filter several times today.

We rebuilt the four carbs tonight without incident ($108 in parts), so tomorrow I hope to be on the water in a perfectly running 115 Johnson.

'Fingers are crossed.

[Kamper]

I'd suggest having the kits on hand and removing the bowls so you can inspect the innards and spray them with cleaner. Sometimes the bowl gasket is distorted when removed and (with Merc's anyway) you can't probably buy them seperatly. If you decide to remove and refurbish the carbs you should service them on a solid clean surface because there are some tiny bits that love to fly and disapear.

Also, do one carb and then the other. You'll want to have a manual to guide you but if you get really confused it will be helpful to have an assembled model to refer to.

Good luck!

[Curmudgeon]

I wouldn't start tearing carbs apart until they become a confirmed issue (if it ain't broke, don't break it trying to fix it). Find a portable tank and hook that up on the water with a buddy boat around. If the engine runs fine, start looking backwards at your fuel system. If it doesn't run OK, then start looking forward toward the engine.

[Kamper]

Ooops, problem solved. I usually do read to the end before I post a response. Sorry about that!

[BMarkey]

I wound up rebuilding all four carbs, with the assistance of the class and instructor. It went well.

I continued to have water problems in the fuel until I discovered that water was sitting atop the plastic tank after it dripped from the deck plate onto the sending unit. I re-sealed the plate and bought a new O-ring fr it, but a little water is still dripping in from rain and when I wash the boat. I also replaced the sending unit and gasket and so far, so good with the engine, but I need to figure out what to do to keep the water from getting to the top of the tank and just sitting there.

Thanks.

Edited May 21, 2010 by BMarkey

[Curmudgeon]

Tilt the tank slightly ...

[BMarkey]

I tilted the boat and got the water to the bottom of the tank. I emptied the tank a couple of times. Each time, water would get back in.

My assumption is that it was sitting atop the gas tank after either leaking in through the deck plate (just above it), or getting in through a forward compartment and working its way to a low point atop the gas tank, right by the sending unit.

I replaced the sending unit and gasket and sealed the deck plate, but some water is still sitting atop the gas tank after each rain/cleaning. I replaced the deck cap O-ring, but even that didn't help, so maybe I will just swap out the entire plate.

It does appear that the new sending unit/O-ring is keeping the water out of the tank, for now. I was thinking of sealing the sending unit with 5200.

[Curmudgeon]

Your sending unit needs no further 'sealing' if it is gasketed properly. If you feel the need, you might want to use something slightly less tenacious than 5200. It's a much better adhesive than sealant, and much more difficult to remove/replace.