Black Fuel in Carb....

[splashlog]

After replacing the carb with a rebuilt one, the engine quit with greater frquency until no restart was possible.
I drained the carb and the fuel that came out is black.
Please someone set me straight here and tell me it's likely a valve issue?

Fuel going in is clean as clean as can be (2 filters, electric pump, water seperator, 0 ethanol..)

Plugs are sooty. Cold compression test says #1-3=110psi,#4=90psi

my guess is #4 is the culprit..?

I shot a few ounces of MMO into the plug holes and it started to leak from the carb flange...(carb is removed)

Any insights?

I did have a leaking water pump that got some water into the oil last fall. I replaced the pump and did 3 oil changes, engine ran fine up until this black fuel happened...

I will clean the carb and see if she runs again before taking it appart as I might be faced with having to remove the A4 altogether to get at the valves... Engine acess is horible on the Grampian Classic 31...

[ndutton]

This might sound like a dumb question but are you certain your tank didn't get an accidental fill with diesel?

[Dave Neptune]

info

First, a valve is not going to turn the fuel black.

Did you pump some fuel into a clear container to check? Or are you just confident in your filters?

Do you have any additives in the fuel?

The MMO just ran down an intake runner and is dripping out ~~ no worries there.

When she died did she hesitate and stumble or just quit like it was shut off?

Sooty plugs are indicative of a rich mix, poor combustion or both.

Dave Neptune

[splashlog]

First of all thanks for the fast posts...

Fuel is 100% clean, I checked what was coming out of the electric pump thinking it might have been the culprit. Pump is good.

I do use a fuel stabilizer, never had a problem.

No possibility of diesle, I personally fill the tank with gas from the same E-free source every time.

The death was gradual every time, sputtering worse and worse until no restart possible.

I even called the guys that did the carb rebuild and they insist that my fuel supply is to blame as they found rust and evidence of water in the carb...

(That rust was from a really old fuel filter...the water came in through the flame arrest, not the fuel supply..)

Thoughts anyone?

[splashlog]

NB the carb guys are talking about the old carb, not the new rebuilt one..

[Dave Neptune]

splashlog, this black fuel is odd to say the least. The only ""black" I've seen in a carb is from gas hoses going bad from ethanol that have not been upgraded to ethanol resistant fuel lines. Did you replace the fuel lines ever or are they really old? The black will look a bit powdery in the fuel, was it dusty black?

How & why is water getting into the spark arrester?

Stumbling to a stop does sound like a fuel or carb issue. Before we tear into the carb inspect the fuel lines and do confirm a good blue snappy spark. And do confirm that the choke is opening and closing completely with a visual inspection.

Did the carb guys use any kind of a sealer on the carb?

Dave Neptune

[joe_db]

Can we be specific?
Is the carb clean and dry but if you drain the float bowl the fuel is black?
Or is it that the carb has black liquid in the throat visible if you take the flame arrestor off?

[JOHN COOKSON]

splashlog, this black fuel is odd to say the least. The only ""black" I've seen in a carb is from gas hoses going bad from ethanol that have not been upgraded to ethanol resistant fuel lines. Did you replace the fuel lines ever or are they really old? The black will look a bit powdery in the fuel, was it dusty black?
Dave Neptune

Did the rebuild folks use inappropriate hose between the fuel pump and the new carburetor? Maybe bits black rubber are in the carb and have jammed some of the passages.

TRUE GRIT

[JOHN COOKSON]

Fuel is 100% clean, I checked what was coming out of the electric pump thinking it might have been the culprit. Pump is good.
I personally fill the tank with gas from the same E-free source every time.
Thoughts anyone?

There is usually not a lot between the fuel pump and the carburetor on an A4.
Some sort of tubing and perhaps a filter and\or a fuel pressure gauge.
If the fuel leaving the fuel pump is normal but the fuel in the carburetor is contaminated what happened in between the two devices?
You tell us. Can't wait to hear.

TRUE GRIT

[splashlog]

Gentlemen, thank you for posting yet again.

Today I pulled the carb appart just for kicks. Didn't find anything odd, reinstalled it and tried the engine. Kind of tried to fire sort of, but wouldn't run. Pulled the carb off again, fuel looks ok. No black stuff.

Inspected the fuel lines, they also look ok, I thought maybe, when I put the rebuild on there might have been some residue in the line that came loose when dis and re connecting the fuel line. That so far is my best guess now that I have fuel back in the carb and appears ok.

The rebuild folks only exchanged my old carb for a rebuilt one, they had nothing to do with the fuel delivery system, fuel lines, etc..

The water on the old carb was probably getting in through the flame arrestor mainly because the boat leaks from many place above the engine. When I aquired the boat, the PO had a plastic bag over the carb to "keep it dry", "Just remember to remove it when you use the engine..." lol. Needless to say I fashioned a cover from a plastic beverage container to take place of the plastic bag..Which I thought was not only super cost effective but rather brilliant..and have had no problems with it, that is it just lives there and never needs to be removed.

So, maybe it is an ignition issue after all. I pulled the plugs and they were wet so I am assuming fuel is making it into the cylinders. I suppose one factor may just be stale fuel, but she ran fine with this same gas just a few days ago, nothing has changed fuel wise, it's still the same gas as before.

I want to see the plugs fire, but I can't be in two places at the same time. It's not possible for me to push the start button and be doing boat yoga with the plugs at the same time....

That's all I got for now. Thanks for all the input so far..

Sorry for any Typos, not sure how to spellcheck here.

[JOHN COOKSON]

I want to see the plugs fire, but I can't be in two places at the same time. It's not possible for me to push the start button and be doing boat yoga with the plugs at the same time..
.

A remote start switch is good tool to have on a boat.

TRUE GRIT

[capnward]

idle jet is the bottleneck.

When you pulled the carb apart, did you remove the jets, particularly the idle jet, and inspect it for blockage? If not, did you run a wire from a wire brush around in the jet to dislodge any crud? Spraying through it with carb cleaner may not be enough. If you did neither, you haven't really cleaned the carb. Your rebuilt carb may have an issue, if your fuel is clean. Your fuel may look clean when you inspect it, but it only takes one tiny particle to partially clog the idle jet. Also run a wire in the small holes in the side of the carb throat, above the butterfly valve. Did you replace the fuel filters when replacing the carb?
Does the choke open and close all the way? If it doesn't close all the way it won't start cold. If it doesn't open enough, it won't run well if at all, and the plugs foul.
If you suspect crud in the fuel, replace the fuel filters when you clean the carb. Clogged filters will send crud into the carb. and restrict fuel flow.The gradual sputtering death indicates a fuel problem. Drain your water separator filter to check for water in the bowl.
On my boat I can remove the starter button from the panel, and into the interior above the engine, to crank it while looking at the spark, but a remote start switch is better.
I think it's essential to use MMO in the fuel. My theory is it lubricates the inside of the carb and helps keep crud from sticking in the jets. Stabilizer is not the same thing.

[Sam]

It was mentioned on an earlier topic/thread - remote starter from "Harbor Freight". Picked one up for $12, came in handy already.

[joe_db]

I have a second start button near the engine. Very useful.

[splashlog]

Hmm, starter remote eh? That's not a bad idea..I probably have enough bits and pieces to make one come to think of it. Thanks for the great tip Folks!

And no I didn't really clean too much in the carb, I need to get a diagram for it so I can understand it a bit better. There seems to be only one needle (on the top, coming in on a angle) not sure what it's for yet. It's backed out .5 turns from all the way in....it came that way from the carb guys and I am ASSUMING they matched it to the original...Please hold back your laughter at least for now..
All the filters are brand new.
I have not checked the choke plate yet.
Anyway it will be a day or two before I can get back to the boat so stay tuned and thanks again for all the great input..