Carbon deposits on plugs

[High Hopes]

My money is on #2 if everything worked fine before that.

#4 I pulled all the oil out and added 3 quarts back in to mine. Is the oil level different than before when you didn't have the problem?

#5 The engine is off the boat.

#7 Here is a picture of my carb before the rebuild.

Good luck. - Steve

[Don Moyer]

In troubleshooting, it's always productive to consider very seriously anything that changed between the time the engine last ran OK and the time the problem began. In your case, Mixing Ethanol and MTBE fuel was apparently the only such change in your operating conditions.

Mixing Ethanol and MTBE fuel was one of the items that Boat US cautioned us to avoid several years ago, since it was known/believed to cause problems which related to carbon build-up on valves. This condition would relate in a general way to your plug issue as well. If it's not too difficult, you could rig up an auxiliary fuel supply to see if your problem goes away. In your case, you should know in 15 minutes or so rather than waiting till you refuel enough to have pure MTBE fuel.

If the problem persists after getting rid of your Ethanol/MTBE fuel mix and all of the other things you and Steve are talking about, you may have to consider elevated exhaust back pressure (which would handily explain your symptoms). I don't know why your back pressure would change just after your trip, but then we would have trouble explaining why anything changed just after your trip. All of which gives credence to resolving the Ethanol/MTBE fuel mix issue first.

Don

[Moby]

Maybe this video will help although it sounds OK to me.

http://video.google.com/videoplay?docid=869087388662302464&hl=en

The spark plugs were just replace and the engine was warm. I know, it's not pretty (yet) but I just want it to run. I almost didn't make it into the slip yesterday because it died at the critical moment. I went out with clean plugs and came back with this:


I think it's the gas so I'm going to try some Stabil additive.

[blackdove]

Sooty plugs

Hi Moby,

I think that Don hit the nail on the head...a combination of ethanol and MBTE is not conducive to an engine that doesn't run pretty hot. Adding the Stabil may just further complicate the problem. The chemistry of these additives is pretty neat and works well individually, but when mixed, it's similar to an oil/vinegar mix and creates phase seperation in the fuel tank. It could also be generating some moisture depending on the head space in the tank.

My recommendation would be to remove the existing fuel mixture and start fresh. Otherwise, your fuel tank is going to resemble a Gilbert Chemistry set and it will confound solving the soot issue. Hope this helps.

Blackdove

[High Hopes]

Hi Moby,

Otherwise, your fuel tank is going to resemble a Gilbert Chemistry set and it will confound solving the soot issue. Hope this helps.

Blackdove

This is completely off topic, but Whoa! Turn back the hands of time! - A Gilbert Chemistry Set. I had two of these. One of the frist things to do was to mix everything together and see what happened. One got useless gunk (like Moby's gasoline problem?). I think I was 9 at the time.

Thanks for the flashback trigger, Blacky.

Steve

[Moby]

Blackdove,

Yes, I am concerned about the chemical goop (oh yes, I had a chemistry set too!). I have ethanol, mtbe, lead substitute, MMO, and Stabil. I figure I have about 10 gallons left in it so I might just siphon it out and burn it in the lawnmower (see if that chokes the mower!). I just want my boat to have a reliable engine so I can get in and out of the marina without bashing into things.

I'm wondering if I should rebuild the carburetor. Is is possible the main jet is gone or corroded open? Could the float be flooded and the bowl getting too full? Could that cause it to run rich?

My other concern is once I solve this problem how do I get the carbon out of the engine?

With all of you guys helping me I'm sure I'll get to the bottom of this issue!

P.S. Did you watch the video? Does the engine sound OK?

[blackdove]

Gilbert and the Sooty Plugs

Hi Moby and Steve,
Yeah, I did the same thing...mixed everything together and got one heck of a gunky mess.

I don't think I'm qualified to speak about the carb...that's a question for those who really know engines, etc. The mixture of the stuff in the tank is almost like an oil fuel rather than gasoline. It is possible that it could be creating carb problems but I don't know that.

I do know that the combination of the group in your fuel tank is going to continue to give you fits. Back to my original rec...empty it out and start afresh with MMO only. My understanding of the chemistry here is that it should help to get the carbon out of the engine (probably more gunk form than soot-like). I would also think that once the engine gets running again in a good mode, the carbon/gunk in the engine would burn off.

Again, hope this helps.

Blackdove

[sunnnnseeeker]

I would focus on getting good gasoline to the engine and give it a chance to get back to normal. If after some running with clean gas if it doesn't straighten out then you can focus on the other issues, if they still exists. I think the engine will clean itself up.

[High Hopes]

Moby,

Take our collective recommendation. Get some fresh gasoline, disconnect your tank, run your A4 fuel line into the fresh gas, and see what happens.

Steve

[Moby]

Thanks all. I will get fresh gas and let you know what happens. After talking with some other boaters they buy gas at the gas station and bring it to the boat. The gas is fresher and not prone to getting water as much as a marine pump (just don't go to one with a car wash!).

I will probably drain the tank into some containers (proper ones of course) then fill with fresh gas.

[Don Moyer]

Bravo! I would like to second this recommendation. We have had other case
histories in the Atomic 4 fleet where additives that in and of themselves
had no ill effects, created nasty precipitates and other compounds that
would settle out of the fuel and cause negative unintended consequences when
mixed in a fuel tank.

This phenomenon always reminds me of my mother in her later years. By the
time she passed away a year or so ago, she was on so much medication that
every now and then she had to be taken off everything and "de-toxed"
completely because all the medicine (while each one may have been very
credible individually) when taken together had her body completely screwed
up chemically.

Don

[Moby]

LOGIC PREVAILS!!!

By the process of elimination it was bad gas!

After I put in the StaBil stuff, I went out the next day and the engine ran really rough, even with clean plugs. I barely made it back. There was no power in gear and I had to modulate the gear shifter to keep it from stalling. Got to the slip and thought the plugs must be fouled again so I decided to come back the next day with some fresh gas and see if I could rig a temporary fuel line to check things out.

So the next day I pulled the plugs and they were clean! I started the engine and it ran great. At the dock I put it in gear and throttled up fine. So, I took it out and ran around the harbor for about an hour at top speed, getting the engine up to about 180F (I don't have a thermostat, just a restrictor valve, so I can control the temp). I had plenty of power, got back to the slip and the plugs were clean! I even looked in the cylinders it the carbon was gone!

I suspect the StaBil stuff collected some water or other crap that was in the bad gas and that's what caused the engine to run rough the first time after I put it in the gas. After that, it ran great. It even sounds better, smoother. That stuff is worth its weight in gold!

Case closed. Thanks for all your help. Logic dictated that the one thing that was changed before the engine went bad was the thing that caused it.

Till next time, this is Moby signing off and sailing into the sunset.

[Moby]

OK, one problem remains. Do I fill up at the same place with MTBE gas or do I go to a filling station and get E10? I really don't want to recreate the problem.