Water in carburetor

[johndowney]

Infuriating sporadic problem with water getting into the carb. I've been trying to figure this one out for some time as it's inconsistent but when she wouldn't start again today I knew exactly what to do and drained the carb to find the offending brown water drops coming out with the gas. I have meticulously been through the filtration system over the years and found no problem there. (I have three filters on the line...1 Sierra, 1 racor and just before the carb there's an inline. So filtration is well covered!) I have tested the gas coming through and no sign of water.
It suddenly occurred to me that maybe there's a hairline crack in the manifold that is allowing a small amount of cooling water to drain back into the carb through the port when the engine is at rest. Any thoughts on this? The water is brown.
When the engine runs, its just fine with no lumpiness that might suggest water.
I'd prefer not to pull the manifold but if you knowledgeable guys think that may be the issue then I'll go ahead and get it magna-fluxed.
Thanks...John

[Dave Neptune]

John, are you finding the water in the "float bowl" or in the throat of the carb?

If water is in the throat the water could be coming in from above like a crack or leak in the manifold.

If the water is in the float bowl it is most likely from the fuel supply. Your tank may have the bottom that is just below the "pick-up" tube full of water and when sailing or rocking it will show up but not necessarily on a "calm" no rocking day.

Dave Neptune

[Administrator]

You can usually discover a leak in the manifold water jacket rather easily by removing both hoses, holding your thumb over one of the brass fittings (on most boats the rear fitting is usually the easiest to reach and block with a thumb or finger), and then blowing into the fitting on the other end of the manifold. If access is limited on both ends of the manifold, you can pick up a short length of 1/2 ID hose at any auto parts store to extend one end until you can blow into the hose by mouth.

Bill

[joe_db]

My old engine did this when water migrated along the manifold bolts. Also it can be exhaust flooding.

[hanleyclifford]

You can usually discover a leak in the manifold water jacket rather easily by removing both hoses, holding your thumb over one of the brass fittings (on most boats the rear fitting is usually the easiest to reach and block with a thumb or finger), and then blowing into the fitting on the other end of the manifold. If access is limited on both ends of the manifold, you can pick up a short length of 1/2 ID hose at any auto parts store to extend one end until you can blow into the hose by mouth.

Bill

A manifold pressure test is now in order.

[johndowney]

Thanks for the opinions gents. I'm fairly confident of the fuel supply integrity as last year I actually drained the tank entirely and replaced with fresh gas. I've replaced the fuel hoses and filters. I haven't left the slip since the time all was fine and the latest episode of water in the carb, so sloshing in the tank is unlikely. Plus I've checked the supply at multiple points in the system and everything is "crystal" (if I may quote Jack Nicholson!) until I get to the carb. Water is in the float chamber.
I opened up the carb last night and along with the water was a fair amount of debris...small dark particles and some powdery residue. (Salt from the cooling system?) I realize the debris points to supply unless it's falling down from the manifold. Just ran my finger around the inside of the manifold intake and it seems to be moist and oily. Time to pull it off for a good pressure check. Need to order a manifold gasket first in case this one is history.
Happy 4th everyone...guess what I'm going to be doing!

[edwardc]

...Water is in the float chamber.
I opened up the carb last night and along with the water was a fair amount of debris...small dark particles and some powdery residue. (Salt from the cooling system?) I realize the debris points to supply unless it's falling down from the manifold. ...

Unless I'm seriously confused, I don't see any way for any kind of leak in the manifold or cooling jacket to get water into the carb's float chamber. They're all downstream of the carb. The ONLY way into the float chamber is through the fuel line. The debris and water has to be coming from your tank or filters.

[Administrator]

What was the condition of the fuel you took out of the tank last year?

Bill

[BunnyPlanet169]

"Small dark particles".... Didn't we have a thread a while back about non-A1 fuel lines slowly deteriorating?

[JOHN COOKSON]

There is a way to nail this down: Run off an auxiliary tank and see if the water in the gas goes away.
The original poster said he drained the tank and overhauled the boat's fuel system last year. Sorry to be the bearer of bad news here but this ethanol laced crap that is sold in the place of real gasoline nowadays has a nasty habit of of puling water in which combines with the ethanol, phase separates, and sinks to the bottom of the tank.This may be very well what is going on. Another suspect is the fill cap might not be tight and is letting water get into the tank.
IMO the tank as a source of water in the carb is very much in play until proven otherwise.

TRUE GRIT

[ndutton]

Despite last year's tank drain and fresh fuel and the accompanying confidence it brought, the consensus is you are dealing with contaminated fuel. After you confirm that for yourself (I think you already have) you'll have to find the source of the contamination or else you're doomed to repeated episodes, like now.

For starters, simply draining the tank and refueling may not be thorough enough. Residual muck in the bottom of the tank often contaminates the fresh fuel and here we go again. Consider that the muck came from somewhere so cleaning the tank only prepares it to receive fresh muck, the reason the source must be found.

And as mentioned previously, while you're at it confirm all your fuel hoses are rated A1-15 ALCOL, the big fuel fill hose too. If they're not you can expect continuing contamination problems.

[hanleyclifford]

Unless I'm seriously confused, I don't see any way for any kind of leak in the manifold or cooling jacket to get water into the carb's float chamber. They're all downstream of the carb. The ONLY way into the float chamber is through the fuel line. The debris and water has to be coming from your tank or filters.

So it would seem--however, the carb is downhill from the manifold so if sufficient water was getting to the throttle bore area it is conceivable something could get into the idle ports and thence to the interior of the carb. Far fetched? Perhaps, but we have seen some strange things here.

[hanleyclifford]

The Horrible Worst Case Scenario

Butterfly is a nice tight seal. Manifold leaks water into intake port, thence to bore. Glug glug down the hole...

[ndutton]

John's suggested auxiliary tank test in post #10 will yield excellent information and provide a clear direction toward resolution. Highly recommended.

[hanleyclifford]

Even easier

After next running leave the throttle wide open overnight and place a container under the carb to see what collects, or not.