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Old 06-13-2016, 10:29 AM
sandiegomike sandiegomike is offline
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Excess Fuel?

Hi, I have rebuilt my late model carbuator and continue to get what seems like excessive fuel coming in and misting up through the spark arrestor. I had another guy work on this a second time and the samething is happening. The engine does start, but "chugs." Advancing the throttle does not increase RPM. Some of the other things we have done: we have checked timing, plug wires 1, 2 4, 3, changed cap, rotor, condenser,points, new plug wires and spark plugs. We have checked compression and it is ok. We believe the issue is the carburator? The electric fuel pump is working. The floats are parallel to the carb as outlined in Moyer's service and overhaul manual. The idle pin was seated and backed out 1.5 turns.

The water pump is working and we are discharging cooling water.

Any thoughts or questions to help guide us?

Last edited by sandiegomike; 06-13-2016 at 04:29 PM.
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Old 06-13-2016, 05:50 PM
JOHN COOKSON JOHN COOKSON is offline
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Yes, It's The Carburetor

Mike
Welcome to the forum.
One scenario is pieces of KRAP in the fuel are blocking the float needle valve and holding it open and flooding the carb. Serial carburetor fixing will get you nothing but more frustrated. You need to supply the carb with pristine clean fuel.
Another possibly is the float needle valve is not sealing the inlet all the way for some reason - maybe wear or corrosion.
To prove or disprove all this clean the carburetor one more time then run off an auxiliary tank with clean fuel and see if the symptoms go away. My guess is there is KRAP in the boat's tank that is getting past the filters. Do you have a polishing filter between the fuel pump & carb? Might be something to consider if you don't.

TRUE GRIT

Edit: I presume the float drop is set correctly?

Last edited by JOHN COOKSON; 06-13-2016 at 07:06 PM.
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Old 06-13-2016, 10:04 PM
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Don Video

Dont mean to separate you and $12.50 unnecessarily - but Don video available through online store gives clear and concise info on carb troubleshoot. I know I learned a lot.
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Old 06-13-2016, 11:05 PM
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I went through a period of float valve clogging/staying open caused BY the polishing filter. The internals of the polishing filter were plain steel, and were corroding due to slight moisture in the fuel. And guess where the corrosion products went??
If your polishing filter is more than two years old, replace it. Avoid the months of carb cleaning that I went through.
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Old 06-13-2016, 11:40 PM
sandiegomike sandiegomike is offline
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Thanks all. I am actually using an auxilary tank with brand new fuel as of 2 weeks ago. I also should have mentioned I have 3 fuel filters. The first one is a water separator, the second is the original can style and the third is an inline between the fuel pump and the carb. The fuel system between the tank and the carb are tight as I have a pump ball between the tank and the first filter to prime and pressurize as to check for "non tight" connections. Filters are all new in the last 3 weeks. I quit using the on board tank about 5 years ago because it is full of gunk. This is a 1968 Columbia 27.
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Old 06-13-2016, 11:45 PM
sandiegomike sandiegomike is offline
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John Cookson "Edit: I presume the float drop is set correctly?"

I am not sure what this means. Can you explain a bit. I have not seen float drop anywhere? We do have the float setting parallel to the carb seam - where the halves separate as a reference.

Last edited by sandiegomike; 06-14-2016 at 12:26 AM.
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Old 06-13-2016, 11:46 PM
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why did you rebuild the carb?
Was the engine running before?
You say that the throttle will not change RPM?
What RPM is it at?
Is the choke closed or open?
How is the compression?
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Old 06-13-2016, 11:47 PM
sandiegomike sandiegomike is offline
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Whippet - thanks, I will order the video for $12.50.
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Old 06-14-2016, 12:13 AM
sandiegomike sandiegomike is offline
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Romantic, thanks for the reply. The engine was running fine in November 2015. I went to start it in March and there was no raw water exhaust, so we did an unclog on the exhaust manifold and then a compression check. We found the exhaust valve stuck open on number 3. We removed the head and unstuck the valve. Replaced the head gasket, exhaust gasket, exhaust manifold gasket. We got the engine running, but not strong...not sure of the RPM but I walk faster. Compression from what I recall is 90-100psi. Choke is working fine. We rebuilt the carb because everything else seemed to be running good - good compression, good fuel, good fuel flow, good spark (tested with a spark tester) , good exhaust water, good spark at points, good timing - just a lot of spitting of fuel up through the spark arrester and seems like excess fuel on the plugs.

Last edited by sandiegomike; 06-14-2016 at 12:18 AM.
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Old 06-14-2016, 12:56 AM
JOHN COOKSON JOHN COOKSON is offline
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Quote:
Originally Posted by sandiegomike View Post
John Cookson "Edit: I presume the float drop is set correctly?"
I am not sure what this means. Can you explain a bit. I have not seen float drop anywhere? We do have the float setting parallel to the carb seam - where the halves separate as a reference.
I have it in a PDF file. Lower right.

TRUE GRIT
Attached Images
File Type: pdf Scan 2-3.pdf (3.02 MB, 1024 views)

Last edited by JOHN COOKSON; 06-14-2016 at 12:58 AM.
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Old 06-26-2016, 09:50 AM
sandiegomike sandiegomike is offline
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Issues continue

Hi all, issues continue, but now I think I have the "too much fuel" issue taken care of by adjusting the float drop, but now won't start. I will readjust in the next couple days. I am learning a lot about carburetors based on your help and a good friend of mine. We will also perform another compression test.

John Cookson, where did you get your fuel pressure gauge?

Last edited by sandiegomike; 06-26-2016 at 09:53 AM.
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Old 06-26-2016, 10:18 AM
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Quote:
Originally Posted by sandiegomike View Post
...where did you get your fuel pressure gauge?
Quite a few of us use this one...

https://www.amazon.com/Mr-Gasket-156...sure+gauge+kit
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Old 06-26-2016, 11:02 AM
JOHN COOKSON JOHN COOKSON is offline
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Since the engine won't start, before pursing the fuel side further, be sure you are getting spark.Here's a simple test. Pull a boot off a spark plug, put a screw driver in it and hold it near the spark plug and see if you can jump an arc to the spark plug while cranking the engine.
I didn't reread the thread: Are you keeping the cooling raw water valve closed when you are cranking the no start engine?

TRUE GRIT
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Old 06-27-2016, 11:52 PM
sandiegomike sandiegomike is offline
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Fuel pressure gauge

Guys,
Thanks for the link to the fuel pressure gauge.
John, yes the raw water is closed during cranking. I will try the arc jumping test, but think I am good. I have a spark tester I have used to confirm spark.

Last edited by sandiegomike; 06-27-2016 at 11:57 PM.
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Old 06-29-2016, 11:17 PM
sandiegomike sandiegomike is offline
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Now no compression

Ok, now we have no compression on 2,3 and 4. The large valve moves on 2 and 3 and on 4 the large valve is not moving. When we originally removed the head 5 weeks ago only the small valve on 3 was stuck, which we thought we cleaned well enough and reinstalled. Number 1 has 95 psi compression. Which all of them had when we reassembled everything 4-5 weeks ago.

Question: Is there something we can do to polish the valve stems and valve guides so they don't stick?

Is this considered carbon build-up?

Is there a round brush or polishing device to use on the valve guide?

The head gaskets are new from 5 weeks ago and also the valve cover plate. Do I need to purchase new gaskets again?

Wisdom and guidance appreciated!
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Old 06-30-2016, 12:54 AM
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Marvel Mystery Oil (MMO) is your friend.

Put a tablespoon or two into each of the cylinders via the spark plug holes. Turn the engine over by hand to distribute the oil and let it sit for a day. Repeat. After a couple of days, try the compression check again. The valves will eventually loosen, but it may take time.

Once running, add a pint of MMO to the oil to get at the lower end, and some in the gas to get at the upper end. You may get some smoke, and the plugs may run a little dirtier, but it will clear up most stuck valve problems. After one tank of gas with MMO, you should probably return to straight gas, but there's no harm in running with the MMO in the oil all the time..
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Old 06-30-2016, 01:26 AM
JOHN COOKSON JOHN COOKSON is offline
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Maybe you could use a trigger type oil can to direct the MMO in the direction of the valves. I've never tried this but it sounds like it should work.
After the MMO treatment, before doing a compression check, you can get rid of a lot of the excess MMO by placing a rag over the top of the engine and then turning the engine with the starter.

TRUE GRIT
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Old 06-30-2016, 10:45 PM
sandiegomike sandiegomike is offline
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Thumbs up Great!

Thanks Guys, BajahahaJim and I will give it a shot. We will keep you posted. I'll head to the harbor this Saturday.
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Old 07-05-2016, 10:32 PM
sandiegomike sandiegomike is offline
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Black gunk in carb.

So BajaHahaJim and I pretty much got the valves unstuck in 2,3 and 4. Is it possible when both valves are stuck open in one cylinder that mystery oil can get pumed back into the carb? This is really thick black gunk and it appears to be comming through the little copper tube connected to the manifold. The other end is connected to the base of the carb close to the spark arrestor. We believe some is coming down through the carb where it is connected to the manifold also, but not sure. I am thinking it is MMO and once getting fired in the cylinder turns thick black.

We think this clogs everything up and causes fuel to be spitting up through the spark arrestor? Does that sound possible?

By the way, we removed the head to get the valves unstuck.
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Old 07-06-2016, 01:25 AM
JOHN COOKSON JOHN COOKSON is offline
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Quote:
Originally Posted by sandiegomike View Post
S. Is it possible when both valves are stuck open in one cylinder that mystery oil can get pumed back into the carb? This is really thick black gunk and it appears to be comming through the little copper tube connected to the manifold. The other end is connected to the base of the carb close to the spark arrestor. We believe some is coming down through the carb where it is connected to the manifold also, but not sure. I am thinking it is MMO and once getting fired in the cylinder turns thick black.

We think this clogs everything up and causes fuel to be spitting up through the spark arrestor? Does that sound possible?
.
You're close here. It's not cause it's effect. The idea behind the little copper tube carb -> manifold is that the vacuum in the manifold will aspirate any fuel in the throat of the carb into the manifold so it doesn't accumulate in the carb and over flow. If the tube is blocked at the manifold or carb this won't happen. The tube is not really part of the carburetor function. The excess fuel is coming from the carb itself, probably because the inlet needle jet is clogged up and not sealing well.

TRUE GRIT
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Old 07-06-2016, 11:13 PM
sandiegomike sandiegomike is offline
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Black Gunk, thanks for the response

Thanks for the guidance on the copper tube. I will check out the fitting going into the manifold on Saturday. Will let you know how it goes. That is probably the reason the gas backs up and shoots out of the spark arrestor. The copper tube and the harden pool of gunk at the entrance to the tube in the carb is part of the problem. I do not remember seeing a bunch of gunk when we had the manifold off though.
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Old 07-07-2016, 01:09 AM
JOHN COOKSON JOHN COOKSON is offline
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Quote:
Originally Posted by sandiegomike View Post
Ok
Question: Is there something we can do to polish the valve stems and valve guides so they don't stick?
Wisdom and guidance appreciated!
Now that you have the valves freed up add MMO to the fuel. The standard dose is 4 ounces of MMO to 10 gallons of fuel. You can double the dose or even increase it more. The downside of this is it will tend to foul the spark plugs a bit.

TRUE GRIT
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Old 07-09-2016, 09:45 AM
sandiegomike sandiegomike is offline
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Pics of the black gunk

Here are a few pictures of the black gunk I spoke about. This has happened twice in the last month while working on the engine. This is what I believe is burnt Mystery Oil coming back through the two stuck open valves. I believe it is coming down through the manifold and up through the copper aspirator tube then hardening. These pictures show the first time this happened. The second time it was much worse, I believe because I had squirted a lot of MMO under the stuck valves. As you can see, this gunk clogs everything.
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Old 07-09-2016, 09:51 AM
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Old 07-09-2016, 09:29 PM
Dave Neptune Dave Neptune is online now
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sandiegomike, I have been looking over this thread and two things come to mind. First are you sure the plugs wires are in the correct order~this could cause the puffing through the arrestor.

Number two is from the KRAP around and leaking through the scavenge assembly I'll bet you have a cracked manifold or a water breach to it. The water would also explain the valves sticking.

Dave Neptune
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Old 07-10-2016, 12:31 AM
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Hi, do you have a fibreglass fuel tank? Sadly, I bet you do, and that black gunk is styrene and etc getting leached out of the tank by methanol. The only cure is a new tank, it seems. You could also try running methanol free gas, obtained from some understanding airport. Make sure you tell them you own a boat, it is illegal to use pure gasoline in a car and they won't sell to you if they think that is what it is for.

edit, this is well known to cause sticking valves http://www.boatus.com/seaworthy/fueltest.asp

Last edited by zesterjester; 07-10-2016 at 12:35 AM. Reason: adding linkj
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